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2020 Volume 31 Issue 8
2020, 31(8): 2027-2028
doi: 10.1016/j.cclet.2020.05.039
Abstract:
2020, 31(8): 2029-2032
doi: 10.1016/j.cclet.2019.12.007
Abstract:
In this paper, the Pt/SnO2 nanostructures were prepared via a facile one-step microwave assisted hydrothermal route. The structure of the introduced Pt/SnO2 and its gas-sensing properties toward CO were investigated. The results from the TEM test reveal that Pt grows on the SnO2 nanostructure, which was not found for bulk in this situ method, constructing Pt/SnO2. The results indicated that the sensor using 3.0 wt% Pt/SnO2 to 100 ppm carbon monoxide performed a superior sensing properties compared to 1.5 wt% and 4.5 wt% Pt/SnO2 at 225 ℃. The response time of 3.0 wt% sensor is 16 s to 100 ppm CO at 225 ℃. Such enhanced gas sensing performances could be attributed to the chemical and electrical factors. In view of chemical factors, the presence of Pt facilitates the surface reaction, which will improve the gas sensing properties. With respect to the electrical factors, the Pt/SnO2 plays roles in increasing the sensor's response due to its characteristic configuration. In addition, the one-step in situ microwave assisted process provides a promising and versatile choice for the preparation of gas sensing materials.
In this paper, the Pt/SnO2 nanostructures were prepared via a facile one-step microwave assisted hydrothermal route. The structure of the introduced Pt/SnO2 and its gas-sensing properties toward CO were investigated. The results from the TEM test reveal that Pt grows on the SnO2 nanostructure, which was not found for bulk in this situ method, constructing Pt/SnO2. The results indicated that the sensor using 3.0 wt% Pt/SnO2 to 100 ppm carbon monoxide performed a superior sensing properties compared to 1.5 wt% and 4.5 wt% Pt/SnO2 at 225 ℃. The response time of 3.0 wt% sensor is 16 s to 100 ppm CO at 225 ℃. Such enhanced gas sensing performances could be attributed to the chemical and electrical factors. In view of chemical factors, the presence of Pt facilitates the surface reaction, which will improve the gas sensing properties. With respect to the electrical factors, the Pt/SnO2 plays roles in increasing the sensor's response due to its characteristic configuration. In addition, the one-step in situ microwave assisted process provides a promising and versatile choice for the preparation of gas sensing materials.
2020, 31(8): 2033-2036
doi: 10.1016/j.cclet.2020.01.002
Abstract:
Noble metal is usually used to improve the gas sensing performance of metal oxide semiconductor (MOS) due to its better catalytic properties. In this work, we reported a synthesis of Pd/ZnO nanocomposite by an in situ reduction with ascorbic acid (AA). It was found that Pd/ZnO sensor has excellent selectivity to CO and the response of the Pd/ZnO sensor towards 100 ppm CO was as high as 15 (Ra/Rg), obviously higher than that of the pristine ZnO sensor (1.4) when the working temperature is 220 ℃. Moreover, the pure ZnO sensor almost has no selectivity to CO, but the Pd/ZnO sensor has excellent selectivity to CO, which may be ascribed to the electronic sensitization of Pd. Our present results demonstrate that the Pd can significantly improve the gas-sensing performance of metal oxide semiconductor and the obtained sensor has great potential in monitoring coal mine gas.
Noble metal is usually used to improve the gas sensing performance of metal oxide semiconductor (MOS) due to its better catalytic properties. In this work, we reported a synthesis of Pd/ZnO nanocomposite by an in situ reduction with ascorbic acid (AA). It was found that Pd/ZnO sensor has excellent selectivity to CO and the response of the Pd/ZnO sensor towards 100 ppm CO was as high as 15 (Ra/Rg), obviously higher than that of the pristine ZnO sensor (1.4) when the working temperature is 220 ℃. Moreover, the pure ZnO sensor almost has no selectivity to CO, but the Pd/ZnO sensor has excellent selectivity to CO, which may be ascribed to the electronic sensitization of Pd. Our present results demonstrate that the Pd can significantly improve the gas-sensing performance of metal oxide semiconductor and the obtained sensor has great potential in monitoring coal mine gas.
2020, 31(8): 2037-2040
doi: 10.1016/j.cclet.2020.01.024
Abstract:
Ag- and Pt-doped WO3·0.33H2O nanorods with high response and selectivity to NH3 were synthesized from a tungsten-containing mineral of scheelite concentrate by a simple combined process, namely by a high pressure leaching method to obtain tungstate ions-containing leaching solution and followed by a hydrothermal method to prepare corresponding nanorods. The microstructure and NH3 sensing performance of the final products were investigated systematically. The microstructure characterization showed that the as-prepared WO3·0.33H2O nanorods had a hexagonal crystal structure, and Ag and Pt nanoparticles were uniformly distributed in the WO3·0.33H2O nanorods. Gas sensing measurements indicated that Ag and Pt nanoparticles not only could obviously enhance NH3 sensing properties in terms of response, selectivity as well as response/recovery time, but also could reduce the optimal operating temperature at which the highest response was achieved. The highest responses of 22.4 and 47.6 for Ag- and Pt-doped WO3·0.33H2O nanorods to 1000 ppm NH3 were obtained at 225 and 175 ℃, respectively, which were about four and eight folds higher than that of pure one at 250 ℃. The superior NH3 sensing properties are mainly ascribed to the catalytic activities of noble metals and the different work functions between noble metals and WO3·0.33H2O.
Ag- and Pt-doped WO3·0.33H2O nanorods with high response and selectivity to NH3 were synthesized from a tungsten-containing mineral of scheelite concentrate by a simple combined process, namely by a high pressure leaching method to obtain tungstate ions-containing leaching solution and followed by a hydrothermal method to prepare corresponding nanorods. The microstructure and NH3 sensing performance of the final products were investigated systematically. The microstructure characterization showed that the as-prepared WO3·0.33H2O nanorods had a hexagonal crystal structure, and Ag and Pt nanoparticles were uniformly distributed in the WO3·0.33H2O nanorods. Gas sensing measurements indicated that Ag and Pt nanoparticles not only could obviously enhance NH3 sensing properties in terms of response, selectivity as well as response/recovery time, but also could reduce the optimal operating temperature at which the highest response was achieved. The highest responses of 22.4 and 47.6 for Ag- and Pt-doped WO3·0.33H2O nanorods to 1000 ppm NH3 were obtained at 225 and 175 ℃, respectively, which were about four and eight folds higher than that of pure one at 250 ℃. The superior NH3 sensing properties are mainly ascribed to the catalytic activities of noble metals and the different work functions between noble metals and WO3·0.33H2O.
2020, 31(8): 2041-2044
doi: 10.1016/j.cclet.2020.04.033
Abstract:
Acetone is an important industrial raw material as well as biomarker in medical diagnosis. The detection of acetone has great significance for safety and health. However, high selectivity and low concentration (ppb level) detection remain challenges for semiconductor gas sensor. Herein, we present a novel sensitive material with bimetallic PtCu nanocrystal modified on WO3·H2O hollow spheres (HS), which shows high sensitivity, excellent selectivity, fast response/recovery speed and low limit of detection (LOD) to acetone detection. Noteworthy, the response (Ra/Rg) of WO3·H2O HS sensor increased by 9.5 times after modification with 0.02% bimetallic PtCu nanocrystals. The response of PtCu/WO3·H2O HS to 50 ppm acetone is as high as 204.9 with short response/recovery times (3.4 s/7.5 s). Finally, the gassensitivity mechanism was discussed based on gas sensitivity test results. This research will offer a new route for high efficient acetone detection.
Acetone is an important industrial raw material as well as biomarker in medical diagnosis. The detection of acetone has great significance for safety and health. However, high selectivity and low concentration (ppb level) detection remain challenges for semiconductor gas sensor. Herein, we present a novel sensitive material with bimetallic PtCu nanocrystal modified on WO3·H2O hollow spheres (HS), which shows high sensitivity, excellent selectivity, fast response/recovery speed and low limit of detection (LOD) to acetone detection. Noteworthy, the response (Ra/Rg) of WO3·H2O HS sensor increased by 9.5 times after modification with 0.02% bimetallic PtCu nanocrystals. The response of PtCu/WO3·H2O HS to 50 ppm acetone is as high as 204.9 with short response/recovery times (3.4 s/7.5 s). Finally, the gassensitivity mechanism was discussed based on gas sensitivity test results. This research will offer a new route for high efficient acetone detection.
2020, 31(8): 2045-2049
doi: 10.1016/j.cclet.2020.04.032
Abstract:
Ethylene (C2H4), as a plant hormone, its emission can be served as an indicator to measure fruit quality. Due to the limited physiochemical reactivity of C2H4, it is a challenge to develop high performance C2H4 sensors for fruit detection. Herein, this paper presents a resistive-type C2H4 sensor based on Pd-loaded tin oxide (SnO2). The C2H4 sensing performance of proposed sensor are tested at optimum operating temperature (250 ℃) with ambient relative humidity (51.9% RH). The results show that the response of Pd-loaded SnO2 sensor (11.1, Ra/Rg) is about 3 times higher than that of pristine SnO2 (3.5) for 100 ppm C2H4. The response time is also significantly shortened from 7 s to 1 s compared with pristine SnO2. Especially, the Pd-loaded SnO2 sensor possesses good sensitivity (0.58 ppm-1) at low concentration (0.05-1 ppm) with excellent linearity (R2=0.9963) and low detection limit (50 ppb). The high sensing performance of Pd-loaded SnO2 are attributed to the excellent adsorption and catalysis effects of Pd nanoparticle. Meaningfully, the potential applications of C2H4 sensor are performed for monitoring the maturity and freshness of fruits, which presents a promising prospect in fruit quality evaluation.
Ethylene (C2H4), as a plant hormone, its emission can be served as an indicator to measure fruit quality. Due to the limited physiochemical reactivity of C2H4, it is a challenge to develop high performance C2H4 sensors for fruit detection. Herein, this paper presents a resistive-type C2H4 sensor based on Pd-loaded tin oxide (SnO2). The C2H4 sensing performance of proposed sensor are tested at optimum operating temperature (250 ℃) with ambient relative humidity (51.9% RH). The results show that the response of Pd-loaded SnO2 sensor (11.1, Ra/Rg) is about 3 times higher than that of pristine SnO2 (3.5) for 100 ppm C2H4. The response time is also significantly shortened from 7 s to 1 s compared with pristine SnO2. Especially, the Pd-loaded SnO2 sensor possesses good sensitivity (0.58 ppm-1) at low concentration (0.05-1 ppm) with excellent linearity (R2=0.9963) and low detection limit (50 ppb). The high sensing performance of Pd-loaded SnO2 are attributed to the excellent adsorption and catalysis effects of Pd nanoparticle. Meaningfully, the potential applications of C2H4 sensor are performed for monitoring the maturity and freshness of fruits, which presents a promising prospect in fruit quality evaluation.
2020, 31(8): 2050-2054
doi: 10.1016/j.cclet.2019.11.024
Abstract:
This paper reports a high-performance H2S gas sensing material that is made of ZnO nanowires (NWs) modified by an optimal amount of ZnS to form nano-heterojunctions. Compared with the intrinsic ZnONWs, the three differently modified nano-heterostructure material ZnO-ZnS-x (x=5, 10, 15) shows significant improvement in sensing performance to H2S at the working temperatures of 100 400 ℃, especially in the low temperature range (< 300 ℃). The chemiresistive sensor with ZnO-ZnS-10 sensingmaterial exhibits the largest response signal to H2S among all the other ZnO-ZnS-x (x=5, 10, 15, 20) sensors. Its response signal to 5 ppm H2S at 150 ℃ is about 2.7 times to that of the ZnO-NWs sensor. Besides, the ZnO-ZnS-10 sensor also features satisfactory selectivity and repeatability at 150 ℃. With the technical advantage attributed to the reduction of the redesigned band gap at the interface between ZnO and ZnS, the ZnO-ZnS heterostructure sensor rather than the traditional ZnO-NWs sensor can be used for high-sensitivity application at low working temperature.
This paper reports a high-performance H2S gas sensing material that is made of ZnO nanowires (NWs) modified by an optimal amount of ZnS to form nano-heterojunctions. Compared with the intrinsic ZnONWs, the three differently modified nano-heterostructure material ZnO-ZnS-x (x=5, 10, 15) shows significant improvement in sensing performance to H2S at the working temperatures of 100 400 ℃, especially in the low temperature range (< 300 ℃). The chemiresistive sensor with ZnO-ZnS-10 sensingmaterial exhibits the largest response signal to H2S among all the other ZnO-ZnS-x (x=5, 10, 15, 20) sensors. Its response signal to 5 ppm H2S at 150 ℃ is about 2.7 times to that of the ZnO-NWs sensor. Besides, the ZnO-ZnS-10 sensor also features satisfactory selectivity and repeatability at 150 ℃. With the technical advantage attributed to the reduction of the redesigned band gap at the interface between ZnO and ZnS, the ZnO-ZnS heterostructure sensor rather than the traditional ZnO-NWs sensor can be used for high-sensitivity application at low working temperature.
2020, 31(8): 2055-2058
doi: 10.1016/j.cclet.2020.01.009
Abstract:
Tin dioxide is important gas sensor material and has wide applications in the detection of toxic gases and volatile organic compounds. Here, we synthesized a 3D laminated structural CuO/SnO2 material possessing p-n heterostructures. The morphology and structure were characterized by XRD, SEM, TEM and XPS techniques and the sensing properties were investigated for the detection of triethylamine (TEA). The results indicate that 3D laminated CuO/SnO2 material, assembled by lamellae consisting of ordered nanoparticles, exhibit an enhanced sensing performance compared with SnO2, and notably, CuO/SnO2 with size less than 1 μm has obvious high selectivity in the detection of 100 ppm TEA. Particularly, it has a high response and stability to 1 and 5 ppm TEA (S is 8 and 33), and that is higher than SnO2 material, suggesting 3D laminated CuO/SnO2 is an effective candidate material served as sensor platform to detect low-concentration amines.
Tin dioxide is important gas sensor material and has wide applications in the detection of toxic gases and volatile organic compounds. Here, we synthesized a 3D laminated structural CuO/SnO2 material possessing p-n heterostructures. The morphology and structure were characterized by XRD, SEM, TEM and XPS techniques and the sensing properties were investigated for the detection of triethylamine (TEA). The results indicate that 3D laminated CuO/SnO2 material, assembled by lamellae consisting of ordered nanoparticles, exhibit an enhanced sensing performance compared with SnO2, and notably, CuO/SnO2 with size less than 1 μm has obvious high selectivity in the detection of 100 ppm TEA. Particularly, it has a high response and stability to 1 and 5 ppm TEA (S is 8 and 33), and that is higher than SnO2 material, suggesting 3D laminated CuO/SnO2 is an effective candidate material served as sensor platform to detect low-concentration amines.
2020, 31(8): 2059-2062
doi: 10.1016/j.cclet.2020.01.012
Abstract:
A homogeneous porous Co3O4-ZnO nanomaterial (Zn-CoOx) was successfully fabricated by precipitationannealing route. The as-prepared Zn-CoOx exhibited good response, reliable reversibility and good selectivity towards alcohols, which attributed to the porous structure and p-n heterojunction formed between Co3O4 and ZnO. In particular, the different Fermi levels of Co3O4 and ZnO leaded to a further increase the depth of the space charge layer, which improved the gas sensitivity of the material from 10% to 480%. Besides, the continuous Co3O4 leaded to a relatively lower operating temperature and resistance. This material preparation method and bimetallic oxides could be widely used in the research and development of metal oxide gas sensitive materials and sensors.
A homogeneous porous Co3O4-ZnO nanomaterial (Zn-CoOx) was successfully fabricated by precipitationannealing route. The as-prepared Zn-CoOx exhibited good response, reliable reversibility and good selectivity towards alcohols, which attributed to the porous structure and p-n heterojunction formed between Co3O4 and ZnO. In particular, the different Fermi levels of Co3O4 and ZnO leaded to a further increase the depth of the space charge layer, which improved the gas sensitivity of the material from 10% to 480%. Besides, the continuous Co3O4 leaded to a relatively lower operating temperature and resistance. This material preparation method and bimetallic oxides could be widely used in the research and development of metal oxide gas sensitive materials and sensors.
2020, 31(8): 2063-2066
doi: 10.1016/j.cclet.2019.11.043
Abstract:
Graphene quantum dots (GQDs) have both the properties of graphene and semiconductor quantum dots, and exhibit stronger quantum confinement effect and boundary effect than graphene. In addition, the band gap of GQDs will transform to non-zero from 0 eV of graphene by surface functionalization, which can be dispersed in common solvents and compounded with solid materials. In this work, the SnO2 nanosheets were prepared by hydrothermal method. As the sensitizer, nitrogen-doped graphene quantum dots (N-GQDs) were prepared and composited with SnO2 nanosheets. Sensing performance of pristine SnO2 and N-GQDs/SnO2 were investigated with HCHO as the target gas. The response (Ra/Rg) of 0.1% N-GQDs/SnO2 was 256 for 100 ppm HCHO at 60 ℃, which was about 2.2 times higher than pristine SnO2 nanosheet. In addition, the material also had excellent selectivity and low operation temperature. The high sensitivity of N-GQDs/SnO2 was attributed to the increase of active sites on materials surface and the electrical regulation of N-GQDs. This research is helpful to develop new HCHO gas sensor and expand the application field of GQDs.
Graphene quantum dots (GQDs) have both the properties of graphene and semiconductor quantum dots, and exhibit stronger quantum confinement effect and boundary effect than graphene. In addition, the band gap of GQDs will transform to non-zero from 0 eV of graphene by surface functionalization, which can be dispersed in common solvents and compounded with solid materials. In this work, the SnO2 nanosheets were prepared by hydrothermal method. As the sensitizer, nitrogen-doped graphene quantum dots (N-GQDs) were prepared and composited with SnO2 nanosheets. Sensing performance of pristine SnO2 and N-GQDs/SnO2 were investigated with HCHO as the target gas. The response (Ra/Rg) of 0.1% N-GQDs/SnO2 was 256 for 100 ppm HCHO at 60 ℃, which was about 2.2 times higher than pristine SnO2 nanosheet. In addition, the material also had excellent selectivity and low operation temperature. The high sensitivity of N-GQDs/SnO2 was attributed to the increase of active sites on materials surface and the electrical regulation of N-GQDs. This research is helpful to develop new HCHO gas sensor and expand the application field of GQDs.
Reduced graphene oxide-porous In2O3 nanocubes hybrid nanocomposites for room-temperature NH3 sensing
2020, 31(8): 2067-2070
doi: 10.1016/j.cclet.2020.01.025
Abstract:
Metal oxide semiconductors (MOS)-reduced graphene oxide (rGO) nanocomposites have attracted great attention for room-temperature gas sensing applications. The development of novel sensing materials is the key issue for the effective detection of ammoniagas at room temperature. In the present work, the novel reduced graphene oxide (rGO)-In2O3 nanocubes hybrid materials have been prepared via a simple electrostatic self-assembly strategy. Characterization results exhibit that the intimate interfacial contact between In2O3 nanocubes and the rGO sheets are achieved. Particularly, the as-prepared rGO/In2O3 nanocomposites displayed high sensitivity, fast response and excellent selectivity towards ammonia (NH3) at room-temperature, which clearly uncovers the merit of structural design and rational integration with rGO sheets. The superior gas sensing performance of the rGO/In2O3 nanocomposites can be attributed to the synergetic effects of rGO sheets and porous In2O3 nanocubes. The reported synthesis offers a general approach to rGO/MOS-based semiconductor composites for room-temperature gas sensing applications.
Metal oxide semiconductors (MOS)-reduced graphene oxide (rGO) nanocomposites have attracted great attention for room-temperature gas sensing applications. The development of novel sensing materials is the key issue for the effective detection of ammoniagas at room temperature. In the present work, the novel reduced graphene oxide (rGO)-In2O3 nanocubes hybrid materials have been prepared via a simple electrostatic self-assembly strategy. Characterization results exhibit that the intimate interfacial contact between In2O3 nanocubes and the rGO sheets are achieved. Particularly, the as-prepared rGO/In2O3 nanocomposites displayed high sensitivity, fast response and excellent selectivity towards ammonia (NH3) at room-temperature, which clearly uncovers the merit of structural design and rational integration with rGO sheets. The superior gas sensing performance of the rGO/In2O3 nanocomposites can be attributed to the synergetic effects of rGO sheets and porous In2O3 nanocubes. The reported synthesis offers a general approach to rGO/MOS-based semiconductor composites for room-temperature gas sensing applications.
2020, 31(8): 2071-2076
doi: 10.1016/j.cclet.2019.12.014
Abstract:
Semiconducting metal oxides have been considered as effective approach for designing high-performance chemical sensing materials. In this paper, a kind of metal-organic frameworks ZIF-8 was used as sacrificed template to prepare porous ZnO hollow nanocubes for the application in gas sensing. It is found that changing calcination temperature and solvent can greatly influence the morphology of the material, which finally affects the gas sensing performance. Acetylene-sensing properties of the sensors were investigated in detail. It can be clearly seen that the material used methanol as reaction solvent with the decomposition at 350 ℃ for 2 h (ZnO-350-M) showed the optimal formaldehyde-sensing behaviors compared with other materials prepared in this experiment. The dynamic transients of the ZnO-350-M-based sensors demonstrated a high response value (about 10), fast response and recovery rate (4 s and 4 s, respectively) and good selectivity towards 100 ppm (part per million) formaldehyde as well as a low detectable limit (1 ppm). As exemplified for the sensing investigation towards formaldehyde, the porous ZnO hollow nanocubes showed a significantly improved chemical sensitivity due to the highly synergistic effects from the well exposed surfaces, defect states and the robust ZnO.
Semiconducting metal oxides have been considered as effective approach for designing high-performance chemical sensing materials. In this paper, a kind of metal-organic frameworks ZIF-8 was used as sacrificed template to prepare porous ZnO hollow nanocubes for the application in gas sensing. It is found that changing calcination temperature and solvent can greatly influence the morphology of the material, which finally affects the gas sensing performance. Acetylene-sensing properties of the sensors were investigated in detail. It can be clearly seen that the material used methanol as reaction solvent with the decomposition at 350 ℃ for 2 h (ZnO-350-M) showed the optimal formaldehyde-sensing behaviors compared with other materials prepared in this experiment. The dynamic transients of the ZnO-350-M-based sensors demonstrated a high response value (about 10), fast response and recovery rate (4 s and 4 s, respectively) and good selectivity towards 100 ppm (part per million) formaldehyde as well as a low detectable limit (1 ppm). As exemplified for the sensing investigation towards formaldehyde, the porous ZnO hollow nanocubes showed a significantly improved chemical sensitivity due to the highly synergistic effects from the well exposed surfaces, defect states and the robust ZnO.
2020, 31(8): 2077-2082
doi: 10.1016/j.cclet.2020.01.011
Abstract:
The morphological and structural design provides an efficient protocol to optimize the performance of gas sensing materials. In this work, a gas sensor with high sensitivity for triethylamine (TEA) detection is developed based on p-type NiCo2O4 hierarchical microspheres. The NiCo2O4 microspheres, synthesized by a hydrothermal route, have a three-dimensional (3D) urchin-like structure assembled by nanorod building blocks. The structure-property correlation has been investigated by powder X-ray diffraction, X-ray photoelectron spectroscopy, transmission electron microscope, scanning electron microscope, N2 adsorption-desorption tests and comprehensive gas sensing experiments. The influence of calcination temperature on the morphological structure and sensing performances has been investigated. Results reveal that the material annealed at 300 ℃ has a very large specific surface area of 125.27 m2/g, thereby demonstrating the best TEA sensing properties including high response and low limit of detection (145 ppb), good selectivity and stability. The further increase of the calcination temperature leads to the collapse of the 3D hierarchical structure with significantly decreased surface area, which is found to decline the sensing performances. This work indicates the promise of ternary p-type metal oxide nanostructures for application in highly sensitive gas sensors.
The morphological and structural design provides an efficient protocol to optimize the performance of gas sensing materials. In this work, a gas sensor with high sensitivity for triethylamine (TEA) detection is developed based on p-type NiCo2O4 hierarchical microspheres. The NiCo2O4 microspheres, synthesized by a hydrothermal route, have a three-dimensional (3D) urchin-like structure assembled by nanorod building blocks. The structure-property correlation has been investigated by powder X-ray diffraction, X-ray photoelectron spectroscopy, transmission electron microscope, scanning electron microscope, N2 adsorption-desorption tests and comprehensive gas sensing experiments. The influence of calcination temperature on the morphological structure and sensing performances has been investigated. Results reveal that the material annealed at 300 ℃ has a very large specific surface area of 125.27 m2/g, thereby demonstrating the best TEA sensing properties including high response and low limit of detection (145 ppb), good selectivity and stability. The further increase of the calcination temperature leads to the collapse of the 3D hierarchical structure with significantly decreased surface area, which is found to decline the sensing performances. This work indicates the promise of ternary p-type metal oxide nanostructures for application in highly sensitive gas sensors.
2020, 31(8): 2083-2086
doi: 10.1016/j.cclet.2019.11.051
Abstract:
Using SnSO4, D-glucose, urea and water, hierarchical shell-core SnO2 microspheres were successfully synthesized via a simple hydrothermal method. The characterization results showed that the sizes of asprepared SnO2 microspheres were 0.6-1 μm, with shell thicknesses of 40-60 nm. The shell and large core of the SnO2 microspheres were all comprised of the same basic rice-like nanoparticles with diameters of 16-25 nm and lengths of 16-45 nm. Further investigaton showed that the glucose and urea served as structural guiding agents, and urea facilitated the formation of the hierarchical structure. The as-prepared SnO2 nanomaterials were used to fabricate a gas sensor with an electrode blade used for the gas sensitivity tests. The hierarchical shell-core SnO2 microspheres exhibited high sensitivity and selectivity toward ethanol, with a responsivity of 63.8 for 50 ppm ethanol at 250 ℃, while the response and recovery time were 7 s and 28 s, respectively. Moreover, the responsivity of the materials showed good linearity at ethanol concentrations from 500 ppb to 10 ppm. The simple synthetic method, environmentally-friendly raw materials, and excellent gas sensitivity demonstrate that the as-prepared SnO2 nanomaterial has great potential applications for the sensing of ethanol gas.
Using SnSO4, D-glucose, urea and water, hierarchical shell-core SnO2 microspheres were successfully synthesized via a simple hydrothermal method. The characterization results showed that the sizes of asprepared SnO2 microspheres were 0.6-1 μm, with shell thicknesses of 40-60 nm. The shell and large core of the SnO2 microspheres were all comprised of the same basic rice-like nanoparticles with diameters of 16-25 nm and lengths of 16-45 nm. Further investigaton showed that the glucose and urea served as structural guiding agents, and urea facilitated the formation of the hierarchical structure. The as-prepared SnO2 nanomaterials were used to fabricate a gas sensor with an electrode blade used for the gas sensitivity tests. The hierarchical shell-core SnO2 microspheres exhibited high sensitivity and selectivity toward ethanol, with a responsivity of 63.8 for 50 ppm ethanol at 250 ℃, while the response and recovery time were 7 s and 28 s, respectively. Moreover, the responsivity of the materials showed good linearity at ethanol concentrations from 500 ppb to 10 ppm. The simple synthetic method, environmentally-friendly raw materials, and excellent gas sensitivity demonstrate that the as-prepared SnO2 nanomaterial has great potential applications for the sensing of ethanol gas.
2020, 31(8): 2087-2090
doi: 10.1016/j.cclet.2020.01.004
Abstract:
Monodispersed ZnSnO3 microspheres are successfully prepared via a facile microwave-assisted method together with subsequently calcination treatment. Powder X-ray diffraction (PXRD) results indicate that the structure of the products shifted from crystalline to amorphous under high-temperature treatments. Field emission scanning electron microscope (FESEM) and the transmission electron microscope (TEM) observations demonstrate that the as-obtained products are composed of uniform microspheres with rough surfaces and the mean diameter is measured as ~700 nm. Moreover, the morphology of ZnSnO3 microspheres can be well controlled by adjusting the ratio of Zn2+ and Sn4+. The gas sensing properties of ZnSnO3 microspheres with different ratios of Zn2+/Sn4+ are investigated. Our results indicate that the ZnSnO3 microspheres exhibit good selectivity and high sensitivity towards ethanol at the optimum working temperature of 230 ℃. When the sensor is exposed 50 ppm ethanol, the value of response is 47 and the response/recovery times are 11 s and 12 s, respectively.
Monodispersed ZnSnO3 microspheres are successfully prepared via a facile microwave-assisted method together with subsequently calcination treatment. Powder X-ray diffraction (PXRD) results indicate that the structure of the products shifted from crystalline to amorphous under high-temperature treatments. Field emission scanning electron microscope (FESEM) and the transmission electron microscope (TEM) observations demonstrate that the as-obtained products are composed of uniform microspheres with rough surfaces and the mean diameter is measured as ~700 nm. Moreover, the morphology of ZnSnO3 microspheres can be well controlled by adjusting the ratio of Zn2+ and Sn4+. The gas sensing properties of ZnSnO3 microspheres with different ratios of Zn2+/Sn4+ are investigated. Our results indicate that the ZnSnO3 microspheres exhibit good selectivity and high sensitivity towards ethanol at the optimum working temperature of 230 ℃. When the sensor is exposed 50 ppm ethanol, the value of response is 47 and the response/recovery times are 11 s and 12 s, respectively.
2020, 31(8): 2091-2094
doi: 10.1016/j.cclet.2020.01.014
Abstract:
Organic amines are important solvent and raw material in laboratory and industry, as well as releasing from cigarette smoke. It is significant to detect low-concentration amines for environment and public health. Here we reported that as-synthesized zinc oxide is an effective electrode material of electrochemical sensor for the detection of amines. The characterization results reveal that the ZnO morphologies experienced a change from hexagonal bowl-like microparticles, cones, prisms to nanoparticles by adjusting the reaction time, temperature, solvents and additives. Interestingly, ZnO material possessing hexagonal shapes and different sizes exhibits distinct electrochemical response in various amines solution, suggesting that there is a better dependent relationship between different morphological ZnO and amines detection. Particularly, regular hexagonal ZnO nanotablets exhibit a detectable electrochemical response and selectivity to ammonia, implying it can be serve as electrode material for highly effective detection of organic amines.
Organic amines are important solvent and raw material in laboratory and industry, as well as releasing from cigarette smoke. It is significant to detect low-concentration amines for environment and public health. Here we reported that as-synthesized zinc oxide is an effective electrode material of electrochemical sensor for the detection of amines. The characterization results reveal that the ZnO morphologies experienced a change from hexagonal bowl-like microparticles, cones, prisms to nanoparticles by adjusting the reaction time, temperature, solvents and additives. Interestingly, ZnO material possessing hexagonal shapes and different sizes exhibits distinct electrochemical response in various amines solution, suggesting that there is a better dependent relationship between different morphological ZnO and amines detection. Particularly, regular hexagonal ZnO nanotablets exhibit a detectable electrochemical response and selectivity to ammonia, implying it can be serve as electrode material for highly effective detection of organic amines.
2020, 31(8): 2095-2098
doi: 10.1016/j.cclet.2020.01.015
Abstract:
It is known that exposed surface determines materialos performance. WO3 is widely used in gas sensing and its working surface is proposed to control its sensitivity. However, the working surface, or most exposed surface with detailed surface structure remain unclear. In this paper, DFT calculation confirmed that oxygen vacancy O-terminated surface is the most exposed hexagonal WO3 (001) surface, judging from competitive adsorption of CO and O2, working surface determination for CO sensing and comparison of oxygen vacancy formation energies on different h-WO3 (001) surfaces. It is found that DFT can be a useful alternate for exposed surface determination. Our results provide new perspectives and performance explanations for material research.
It is known that exposed surface determines materialos performance. WO3 is widely used in gas sensing and its working surface is proposed to control its sensitivity. However, the working surface, or most exposed surface with detailed surface structure remain unclear. In this paper, DFT calculation confirmed that oxygen vacancy O-terminated surface is the most exposed hexagonal WO3 (001) surface, judging from competitive adsorption of CO and O2, working surface determination for CO sensing and comparison of oxygen vacancy formation energies on different h-WO3 (001) surfaces. It is found that DFT can be a useful alternate for exposed surface determination. Our results provide new perspectives and performance explanations for material research.
2020, 31(8): 2099-2102
doi: 10.1016/j.cclet.2019.11.032
Abstract:
In this work, the two-dimensional MoS2 film was prepared by sulfuring the molybdenum atomic layer on SiO2/Si substrate. The reaction temperature, heating rate, holding time and carrier gas flow rate were investigated comprehensively. The quality of MoS2 film was characterized by optical microscopy, atomic force microscopy, Raman and photoluminescence spectroscopy. The characterization results showed that the optimum synthesis parameters were heating rate of 25 ℃/min, reaction temperature of 750 ℃, holding time of 30 min and carrier gas velocity of 100 sccm. The MoS2 gas sensor was fabricated and its gas sensing performance was tested. The test results indicated that the sensor had a good response to both reducing gas (NH3) and oxidizing gas (NO2) at room temperature. The sensitivity to 100 ppm of NO2 was 31.3%, and the response/recovery times were 4 s and 5 s, respectively. In addition, the limit of detection could be as low as 1 ppm. This work helps us to develop low power and integrable room temperature NO2 sensors.
In this work, the two-dimensional MoS2 film was prepared by sulfuring the molybdenum atomic layer on SiO2/Si substrate. The reaction temperature, heating rate, holding time and carrier gas flow rate were investigated comprehensively. The quality of MoS2 film was characterized by optical microscopy, atomic force microscopy, Raman and photoluminescence spectroscopy. The characterization results showed that the optimum synthesis parameters were heating rate of 25 ℃/min, reaction temperature of 750 ℃, holding time of 30 min and carrier gas velocity of 100 sccm. The MoS2 gas sensor was fabricated and its gas sensing performance was tested. The test results indicated that the sensor had a good response to both reducing gas (NH3) and oxidizing gas (NO2) at room temperature. The sensitivity to 100 ppm of NO2 was 31.3%, and the response/recovery times were 4 s and 5 s, respectively. In addition, the limit of detection could be as low as 1 ppm. This work helps us to develop low power and integrable room temperature NO2 sensors.
2020, 31(8): 2103-2108
doi: 10.1016/j.cclet.2020.03.060
Abstract:
MoS2, acting as a promising gas sensing material, has shown huge potential in monitoring of toxic and harmful gases at room temperature. However, MoS2-based gas sensors still suffer from poor gas sensing performance such as poor sensitivity, long response time. Constructing the heterostructure is an effective approach to improve gas-sensing performance of MoS2. Herein, PbS@MoS2 composites synthesized by mechanical exfoliation combining with wet-chemical precipitation are used to investigate its performance in detecting NO2 at room temperature. The response value of PbS@MoS2 gas sensor against NO2 is significantly improved compared with the pure MoS2 gas sensor. At the same time, the modification with PbS also accelerates the response speed of MoS2, and the response time is almost reduced by two orders of magnitude, from hundreds of seconds to less than ten seconds. The enhanced response value and fast response time are mainly benefited from the modulation effect of NO2 to PbS@MoS2 heterostructure and the mechanically exfoliated MoS2 surface with few defects. This work can be expected to provide useful guidance for designing composite materials with excellent gas sensing properties.
MoS2, acting as a promising gas sensing material, has shown huge potential in monitoring of toxic and harmful gases at room temperature. However, MoS2-based gas sensors still suffer from poor gas sensing performance such as poor sensitivity, long response time. Constructing the heterostructure is an effective approach to improve gas-sensing performance of MoS2. Herein, PbS@MoS2 composites synthesized by mechanical exfoliation combining with wet-chemical precipitation are used to investigate its performance in detecting NO2 at room temperature. The response value of PbS@MoS2 gas sensor against NO2 is significantly improved compared with the pure MoS2 gas sensor. At the same time, the modification with PbS also accelerates the response speed of MoS2, and the response time is almost reduced by two orders of magnitude, from hundreds of seconds to less than ten seconds. The enhanced response value and fast response time are mainly benefited from the modulation effect of NO2 to PbS@MoS2 heterostructure and the mechanically exfoliated MoS2 surface with few defects. This work can be expected to provide useful guidance for designing composite materials with excellent gas sensing properties.
2020, 31(8): 2109-2114
doi: 10.1016/j.cclet.2019.12.030
Abstract:
In the work, rGO nanosheet is synthesized using the typical Hummer's method, then Cu12Sb4S13 quantum dots@rGO composites are prepared by solvent thermal method, and Cu12Sb4S13 quantum dots with the average size of 5 nm are densely distributed on the surface of rGO sheet. NH3 gas response of Cu12Sb4S13 quantum dots@rGO nanosheet composites at room temperature of 25 ℃ is enhanced compared with the pure Cu12Sb4S13 quantum dots and rGO nanosheet, and the composites possess an excellent stability during the humidity range of 45%-80% with a low detection limit of 1 ppm, which is related with the intrinsic hydrophobicity characteristic of Cu12Sb4S13 quantum dots. It also proves that Cu12Sb4S13 quantum dots@rGO nanosheet composites have a quite high selectivity towards ammonia compared with ethanol, methanol, acetone, toluene, hydrogen sulfide and nitrogen dioxide at room temperature. The gas sensing mechanism of the composites is discussed primarily.
In the work, rGO nanosheet is synthesized using the typical Hummer's method, then Cu12Sb4S13 quantum dots@rGO composites are prepared by solvent thermal method, and Cu12Sb4S13 quantum dots with the average size of 5 nm are densely distributed on the surface of rGO sheet. NH3 gas response of Cu12Sb4S13 quantum dots@rGO nanosheet composites at room temperature of 25 ℃ is enhanced compared with the pure Cu12Sb4S13 quantum dots and rGO nanosheet, and the composites possess an excellent stability during the humidity range of 45%-80% with a low detection limit of 1 ppm, which is related with the intrinsic hydrophobicity characteristic of Cu12Sb4S13 quantum dots. It also proves that Cu12Sb4S13 quantum dots@rGO nanosheet composites have a quite high selectivity towards ammonia compared with ethanol, methanol, acetone, toluene, hydrogen sulfide and nitrogen dioxide at room temperature. The gas sensing mechanism of the composites is discussed primarily.
2020, 31(8): 2115-2118
doi: 10.1016/j.cclet.2019.12.029
Abstract:
Dihydronicotinamide adenine dinucleotide (NADH) is an important enzyme in all living cells, which is found to be abnormally expressed in cancer cells. Since it is redox-active, an electrochemical detection method would be suitable for monitoring its concentration in biological fluids. Here we present a strategy for specific determination of NADH in real human serum by using RhIr@MoS2 nanohybrids based microsensor. To implement the protocol, RhIr nanocrysrals are in-situ grown onto MoS2 interlayers forming a nanohybrid structure (RhIr@MoS2). After being locally deposited on an electrochemical microsensor, it could be used for the analysis of NADH. The developed RhIr@MoS2 nanohybrids based microsensor possesses the ability for analyzing NADH at the applied potential of 0.07 V (much lower than most reported values). The detection limit is evaluated as low as 1 nmol/L even in bovine serum albumin (BSA) media. In addition, the sampling analysis of human serum from cancer patients and health controls shows that the microsensor displays good diagnostic sensitivity and specificity, illustrating that this developed detection technique is a relatively accurate method for measuring NADH in biological fluids. The proposed electrochemical microsensor assay also owns the benefits of convenience, disposable and easy processing, which make it a great possibility for future point-of-care cancer diagnosis.
Dihydronicotinamide adenine dinucleotide (NADH) is an important enzyme in all living cells, which is found to be abnormally expressed in cancer cells. Since it is redox-active, an electrochemical detection method would be suitable for monitoring its concentration in biological fluids. Here we present a strategy for specific determination of NADH in real human serum by using RhIr@MoS2 nanohybrids based microsensor. To implement the protocol, RhIr nanocrysrals are in-situ grown onto MoS2 interlayers forming a nanohybrid structure (RhIr@MoS2). After being locally deposited on an electrochemical microsensor, it could be used for the analysis of NADH. The developed RhIr@MoS2 nanohybrids based microsensor possesses the ability for analyzing NADH at the applied potential of 0.07 V (much lower than most reported values). The detection limit is evaluated as low as 1 nmol/L even in bovine serum albumin (BSA) media. In addition, the sampling analysis of human serum from cancer patients and health controls shows that the microsensor displays good diagnostic sensitivity and specificity, illustrating that this developed detection technique is a relatively accurate method for measuring NADH in biological fluids. The proposed electrochemical microsensor assay also owns the benefits of convenience, disposable and easy processing, which make it a great possibility for future point-of-care cancer diagnosis.
2020, 31(8): 2119-2124
doi: 10.1016/j.cclet.2020.01.020
Abstract:
Due to the "trade-off" effect between the high water adsorption and low stability under high Relative Humidity of polymer matrix, fabrication of resistive-type polymer-based humidity sensors with a wide impedance response and excellent stability in high relative humidity remains a great challenge. Aim at solving that, a novel polymeric humidity sensing matrix, specifically a tadpole-shaped, polyhedral oligomeric silsesquioxane (POSS) containing block copolymers (BCPs) of POSS-poly(methyl methacrylate)-polystyrene (POSS-PMMA-SPS) were proposed. This novel BCP was synthesized using atom transfer radical polymerization (ATRP) employing a two-step approach, and following post sulfonation, a series of sulfonated BCPs (POSS-PMMA-SPS) with different sulfonation degree was obtained. The subject humidity sensors were produced using different sulfonated BCPs employing a dip-coating technique, and three wide-impedance response humidity sensors were produced. Each of these sensors exhibited an excellent humidity-sensing response of more than 104 within the humidity range from 11% to 95% RH. In particular, the humidity sensor S-6 that had a proper degree of sulfonation presented a relatively fast response (t90% of 11 s and 80 s in both the water adsorption and desorption processes), and superior repeatability for more than 30 days.
Due to the "trade-off" effect between the high water adsorption and low stability under high Relative Humidity of polymer matrix, fabrication of resistive-type polymer-based humidity sensors with a wide impedance response and excellent stability in high relative humidity remains a great challenge. Aim at solving that, a novel polymeric humidity sensing matrix, specifically a tadpole-shaped, polyhedral oligomeric silsesquioxane (POSS) containing block copolymers (BCPs) of POSS-poly(methyl methacrylate)-polystyrene (POSS-PMMA-SPS) were proposed. This novel BCP was synthesized using atom transfer radical polymerization (ATRP) employing a two-step approach, and following post sulfonation, a series of sulfonated BCPs (POSS-PMMA-SPS) with different sulfonation degree was obtained. The subject humidity sensors were produced using different sulfonated BCPs employing a dip-coating technique, and three wide-impedance response humidity sensors were produced. Each of these sensors exhibited an excellent humidity-sensing response of more than 104 within the humidity range from 11% to 95% RH. In particular, the humidity sensor S-6 that had a proper degree of sulfonation presented a relatively fast response (t90% of 11 s and 80 s in both the water adsorption and desorption processes), and superior repeatability for more than 30 days.
2020, 31(8): 2125-2128
doi: 10.1016/j.cclet.2020.02.051
Abstract:
This work reports a superhydrophobic divinylbenzene polymer with hierarchical porous structure as sensing material to modify the quartz crystal microbalance (QCM) to detect benzene, toluene, ethylbenzene, and xylene (BTEX) vapor. Notably, sensing results toward toluene vapor in different relative humidities indicates that this superhydrophobic polymer has favorable toluene/water selective detection performance. Besides, the limit of detection toward toluene is lower than 1 ppm.
This work reports a superhydrophobic divinylbenzene polymer with hierarchical porous structure as sensing material to modify the quartz crystal microbalance (QCM) to detect benzene, toluene, ethylbenzene, and xylene (BTEX) vapor. Notably, sensing results toward toluene vapor in different relative humidities indicates that this superhydrophobic polymer has favorable toluene/water selective detection performance. Besides, the limit of detection toward toluene is lower than 1 ppm.
2020, 31(8): 2129-2132
doi: 10.1016/j.cclet.2020.01.034
Abstract:
In order to improve the convenience and sensitivity of amphetamines drug testing and reduce the threat of drugs to humans, we have designed a QCM gas sensor to detect amine-containing drugs. The sensing material is designed based on the chemical nature of amine drugs. The sensing mechanism is derived from a reversible Schiff base interaction between the amino group of the drug and the carbonyl group of the novel calix[6]arene derivatives as well as the hydrogen bond interaction between amino group and hydroxyl. The new composite material was well characterized by different analytical techniques including 1H nuclear magnetic resonance (1H-NMR), fourier transform infrared spectroscopy (FT-IR), scanning electronic microscopy (SEM), transmission electron microscope (TEM), Raman spectra, powder X-ray diffraction, etc. The sensing experiments were conducted by coating the composite onto quartz crystal microbalance (QCM) transducers. The experimental results indicated that the novel calixarene derivatives and their GO complexes based on the design have excellent selectivity, high sensitivity and repeatability to β-phenylethylamine.
In order to improve the convenience and sensitivity of amphetamines drug testing and reduce the threat of drugs to humans, we have designed a QCM gas sensor to detect amine-containing drugs. The sensing material is designed based on the chemical nature of amine drugs. The sensing mechanism is derived from a reversible Schiff base interaction between the amino group of the drug and the carbonyl group of the novel calix[6]arene derivatives as well as the hydrogen bond interaction between amino group and hydroxyl. The new composite material was well characterized by different analytical techniques including 1H nuclear magnetic resonance (1H-NMR), fourier transform infrared spectroscopy (FT-IR), scanning electronic microscopy (SEM), transmission electron microscope (TEM), Raman spectra, powder X-ray diffraction, etc. The sensing experiments were conducted by coating the composite onto quartz crystal microbalance (QCM) transducers. The experimental results indicated that the novel calixarene derivatives and their GO complexes based on the design have excellent selectivity, high sensitivity and repeatability to β-phenylethylamine.
2020, 31(8): 2133-2136
doi: 10.1016/j.cclet.2019.12.021
Abstract:
V2O5 flower-like structures assembled by thin nanosheets were in-situ growth on ceramic tubes by hydrothermal process. The structural characterization indicates that V2O5 flower-like structures is orthogonal diamond phase, which entirely covered on the surface of ceramic tubes. TMA sensing measured results revealed that the sensor based on V2O5 flower-like structures exhibited fast reversible and response, good selectivity to TMA and good stability at 200 ℃. The good sensing performance may be ascribed to flower-like structures and directly growth sensing film on the ceramic tube without structure damage. Our works give a simple in-situ growth flower-like structures route on sensing device, which exhibits potential application for detecting trace amounts of TMA gas.
V2O5 flower-like structures assembled by thin nanosheets were in-situ growth on ceramic tubes by hydrothermal process. The structural characterization indicates that V2O5 flower-like structures is orthogonal diamond phase, which entirely covered on the surface of ceramic tubes. TMA sensing measured results revealed that the sensor based on V2O5 flower-like structures exhibited fast reversible and response, good selectivity to TMA and good stability at 200 ℃. The good sensing performance may be ascribed to flower-like structures and directly growth sensing film on the ceramic tube without structure damage. Our works give a simple in-situ growth flower-like structures route on sensing device, which exhibits potential application for detecting trace amounts of TMA gas.
2020, 31(8): 2137-2141
doi: 10.1016/j.cclet.2019.12.020
Abstract:
To develop a novel food preservation technology for efficiently enhance bactericidal activity in a long term, hollow mesoporous silica spheres (HMSS) with regular nanostructures were applied to encapsulate natural organic antimicrobial agents. The chemical structures, morphologies and thermal stabilities of linalool, HMSS and linalool-functionalized hollow mesoporous silica spheres (L-HMSS) nanoparticles were evaluated by polarimeter, field emission scanning electron microscope (FE-SEM), transmission electron microscope (TEM), fourier transform infrared (FT-IR), thermal gravimetric analyzer (TGA), nitrogen adsorption-desorption, zeta potential and small angle X-ray diffraction (SXRD). The results show that the linalool was successfully introduced into the cavities of HMSS, and the inorganic host exhibited a high loading capacity of about 1500 mg/g. In addition, after 48 h of incubation, the minimum bactericidal concentrations (MBC) of L-HMSS against Escherichia coli (E. coli), Salmonella enterica (S. enterica) and Staphylococcus aureus (S. aureus), Listeria monocytogenes (L. monocytogenes) were decreased to be 4 (< 5) mg/mL and 8 (< 10) mg/mL, respectively. These results revealed linaloolfunctionalized hollow mesoporous spheres could efficiently improve the bactericidal activities of the organic component. Furthermore, SEM images clearly showed that L-HMSS indeed had an extremely inhibitory effect against gram-negative (E. coli) and gram-positive (S. aureus) by breaking the structure of the cell membrane. This research is of great significance in the application of linalool in nano-delivery system as well as food industry.
To develop a novel food preservation technology for efficiently enhance bactericidal activity in a long term, hollow mesoporous silica spheres (HMSS) with regular nanostructures were applied to encapsulate natural organic antimicrobial agents. The chemical structures, morphologies and thermal stabilities of linalool, HMSS and linalool-functionalized hollow mesoporous silica spheres (L-HMSS) nanoparticles were evaluated by polarimeter, field emission scanning electron microscope (FE-SEM), transmission electron microscope (TEM), fourier transform infrared (FT-IR), thermal gravimetric analyzer (TGA), nitrogen adsorption-desorption, zeta potential and small angle X-ray diffraction (SXRD). The results show that the linalool was successfully introduced into the cavities of HMSS, and the inorganic host exhibited a high loading capacity of about 1500 mg/g. In addition, after 48 h of incubation, the minimum bactericidal concentrations (MBC) of L-HMSS against Escherichia coli (E. coli), Salmonella enterica (S. enterica) and Staphylococcus aureus (S. aureus), Listeria monocytogenes (L. monocytogenes) were decreased to be 4 (< 5) mg/mL and 8 (< 10) mg/mL, respectively. These results revealed linaloolfunctionalized hollow mesoporous spheres could efficiently improve the bactericidal activities of the organic component. Furthermore, SEM images clearly showed that L-HMSS indeed had an extremely inhibitory effect against gram-negative (E. coli) and gram-positive (S. aureus) by breaking the structure of the cell membrane. This research is of great significance in the application of linalool in nano-delivery system as well as food industry.
2020, 31(8): 2142-2144
doi: 10.1016/j.cclet.2019.11.048
Abstract:
Flexible trimethylamine sensor has been realized based on In2O3 nanofibers via electrospinning and a deposition technique. The web-like In2O3 nanofibers with high length-to-diameter ratios are benefit for gas adsorption and desorption. High trimethylamine sensing properties are observed. The sensors can detect trimethylamine gas down to 1 ppm at 80 ℃ with the response up to 3.8. Additionally, rapid response (6 s) and recovery (10 s) behavior can also be obtained. Good reliability and flexibility are observed in 100 bending/extending cycles. Our results open a new route to construct flexible gas sensors in practice.
Flexible trimethylamine sensor has been realized based on In2O3 nanofibers via electrospinning and a deposition technique. The web-like In2O3 nanofibers with high length-to-diameter ratios are benefit for gas adsorption and desorption. High trimethylamine sensing properties are observed. The sensors can detect trimethylamine gas down to 1 ppm at 80 ℃ with the response up to 3.8. Additionally, rapid response (6 s) and recovery (10 s) behavior can also be obtained. Good reliability and flexibility are observed in 100 bending/extending cycles. Our results open a new route to construct flexible gas sensors in practice.
2020, 31(8): 2145-2149
doi: 10.1016/j.cclet.2019.11.050
Abstract:
An optical fiber dual Fabry-Pérot interferometric carbon monoxide gas sensor based on PANI/Co3O4/GO (PCG) sensing membrane coated on the end face of the optical fiber is proposed and fabricated. One end face of photonic crystal fiber (PCF) without cut-off wavelength is fused with a single-mode fiber (SMF), and the other end face of the PCF is coated with PCG sensing membrane. The collapsed layer formed during the air hole fusion of PCF is used as the first reflector, the interface between PCF and sensing membrane is used as the second reflector, and the interface between the sensing membrane and the air is used as the third reflector, thus the dual Fabry-Pérot structure sensor is formed. The results show that the sensor has excellent sensitivity and selectivity to carbon monoxide. With the increasing concentration of carbon monoxide gas in the range of 0-60 ppm, the intensity of interference spectrum decreases. The sensitivity of the sensor is 0.3473 dB m/ppm, and its linearity is good. The response time and recovery time are 68 s and 106 s, respectively. The sensor has the advantages of the compact size, low cost, high sensitivity, strong selectivity and simple structure. It is suitable for the sensing detection of low concentration carbon monoxide gas.
An optical fiber dual Fabry-Pérot interferometric carbon monoxide gas sensor based on PANI/Co3O4/GO (PCG) sensing membrane coated on the end face of the optical fiber is proposed and fabricated. One end face of photonic crystal fiber (PCF) without cut-off wavelength is fused with a single-mode fiber (SMF), and the other end face of the PCF is coated with PCG sensing membrane. The collapsed layer formed during the air hole fusion of PCF is used as the first reflector, the interface between PCF and sensing membrane is used as the second reflector, and the interface between the sensing membrane and the air is used as the third reflector, thus the dual Fabry-Pérot structure sensor is formed. The results show that the sensor has excellent sensitivity and selectivity to carbon monoxide. With the increasing concentration of carbon monoxide gas in the range of 0-60 ppm, the intensity of interference spectrum decreases. The sensitivity of the sensor is 0.3473 dB m/ppm, and its linearity is good. The response time and recovery time are 68 s and 106 s, respectively. The sensor has the advantages of the compact size, low cost, high sensitivity, strong selectivity and simple structure. It is suitable for the sensing detection of low concentration carbon monoxide gas.
2020, 31(8): 2150-2154
doi: 10.1016/j.cclet.2019.12.024
Abstract:
Ordered mesoporous carbon (OMCs) FDU-15 was synthesized through an EISA (Evaporation-Induced Self-Assembly) method, and the oxidized OMCs (FDU-15-COOH) were obtained by subsequent oxidation treatments in liquid phase to introduce functional groups. The samples were characterized by XRD, TEM, FT-IR and nitrogen adsorption-desorption test. The low humidity sensing performances of FDU-15 and FDU-15-COOH thin films were investigated by using a quartz crystal microbalance (QCM) transducer. The responses of FDU-15-COOH is higher than that of the pristine FDU-15 at very low humidity (< 729 ppmv) with high long-term stability, implying that FDU-15-COOH is a good candidate for low humidity QCM sensor.
Ordered mesoporous carbon (OMCs) FDU-15 was synthesized through an EISA (Evaporation-Induced Self-Assembly) method, and the oxidized OMCs (FDU-15-COOH) were obtained by subsequent oxidation treatments in liquid phase to introduce functional groups. The samples were characterized by XRD, TEM, FT-IR and nitrogen adsorption-desorption test. The low humidity sensing performances of FDU-15 and FDU-15-COOH thin films were investigated by using a quartz crystal microbalance (QCM) transducer. The responses of FDU-15-COOH is higher than that of the pristine FDU-15 at very low humidity (< 729 ppmv) with high long-term stability, implying that FDU-15-COOH is a good candidate for low humidity QCM sensor.
2020, 31(8): 2155-2158
doi: 10.1016/j.cclet.2020.01.018
Abstract:
Detection of trace-level hydrogen sulfide (H2S) gas is of great importance whether in industrial production or disease diagnosis. This research presents a novel H2S gas sensor based on integrated resonant dual-microcantilevers which can identify and detect trace-level H2S in real-time. The sensor consists of two integrated resonant microcantilever sensors with different functions. One cantilever sensor can identify H2S by outputting positive frequency shift signals, while the other cantilever sensor will detect H2S as a normally used cantilever sensor with negative frequency shifts. Combined the two cantilever sensors, the proposed gas sensor can distinguish H2S from a variety of common gases, and the detection limit to H2S of the sensor is as sensitive as below 1 ppb.
Detection of trace-level hydrogen sulfide (H2S) gas is of great importance whether in industrial production or disease diagnosis. This research presents a novel H2S gas sensor based on integrated resonant dual-microcantilevers which can identify and detect trace-level H2S in real-time. The sensor consists of two integrated resonant microcantilever sensors with different functions. One cantilever sensor can identify H2S by outputting positive frequency shift signals, while the other cantilever sensor will detect H2S as a normally used cantilever sensor with negative frequency shifts. Combined the two cantilever sensors, the proposed gas sensor can distinguish H2S from a variety of common gases, and the detection limit to H2S of the sensor is as sensitive as below 1 ppb.
