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2022 Volume 41 Issue 1
2022, 41(1): 220100
doi: 10.14102/j.cnki.0254-5861.2021-0016
Abstract:
Recently, the tetrahedral Ti4L6 cage (L = embonate) has been applied as the starting material to realize coordination assembly with transition and rare-earth ornoble metal ions through a two-step reaction. In this work, by employing the Ti4L6 cages to assemble with alkaline-earth metal ions (such as Mg2+, Ca2+ and Ba2+) under different solvothermal conditions, a series of Ti4L6-based structures from simple cages to 1D chain, 2D layer and 3D framework have been synthesized and structurally characterized. In addition, thermal stability, phase purity, UV-vis absorption spectrum, the fluorescent and third-order nonlinear-optical properties are also investigated.
Recently, the tetrahedral Ti4L6 cage (L = embonate) has been applied as the starting material to realize coordination assembly with transition and rare-earth ornoble metal ions through a two-step reaction. In this work, by employing the Ti4L6 cages to assemble with alkaline-earth metal ions (such as Mg2+, Ca2+ and Ba2+) under different solvothermal conditions, a series of Ti4L6-based structures from simple cages to 1D chain, 2D layer and 3D framework have been synthesized and structurally characterized. In addition, thermal stability, phase purity, UV-vis absorption spectrum, the fluorescent and third-order nonlinear-optical properties are also investigated.
2022, 41(1): 220100
doi: 10.14102/j.cnki.0254-5861.2021-0026
Abstract:
ZnIn2S4 has emerged in water splitting and degradation of dyes due to its good stability and light absorption properties. However, there are still few reports of CO2 photoreduction. Herein, we successfully synthesized ZnIn2S4 and obtained a series of ZnIn2S4-CdIn2S4 heterostructured microspheres through the ion exchange method, and first used them in photocatalytic CO2 reduction in noble-metal-free systems. The activity results showed that these ZnIn2S4-CdIn2S4 photocatalysts exhibit excellent catalytic activity under visible light, and the best CO yield is as high as 33.57 μmol·h-1 with a selectivity of 91%. Furthermore, the stability and reusability of ZnIn2S4-CdIn2S4 was firmly confirmed by diverse characterizations, including X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), energy-dispersive X-ray spectroscopy (EDX) and N2 adsorption measurements.
ZnIn2S4 has emerged in water splitting and degradation of dyes due to its good stability and light absorption properties. However, there are still few reports of CO2 photoreduction. Herein, we successfully synthesized ZnIn2S4 and obtained a series of ZnIn2S4-CdIn2S4 heterostructured microspheres through the ion exchange method, and first used them in photocatalytic CO2 reduction in noble-metal-free systems. The activity results showed that these ZnIn2S4-CdIn2S4 photocatalysts exhibit excellent catalytic activity under visible light, and the best CO yield is as high as 33.57 μmol·h-1 with a selectivity of 91%. Furthermore, the stability and reusability of ZnIn2S4-CdIn2S4 was firmly confirmed by diverse characterizations, including X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), energy-dispersive X-ray spectroscopy (EDX) and N2 adsorption measurements.
2022, 41(1): 220101
doi: 10.14102/j.cnki.0254-5861.2021-0037
Abstract:
Hetero-structure induced high performance catalyst for oxygen evolution reaction (OER) in the water splitting reaction has received increased attention. Herein, we demonstrated a novel catalyst system of NiSe2-CoSe2 consisting of nanorods and nanoparticles for the efficient OER in the alkaline electrolyte. This catalyst system can be easily fabricated via a low-temperature selenization of the solvothermal synthesized NiCo(OH)x precursor and the unique morphology of hybrid nanorods and nanoparticles was found by the electron microscopy analysis. The high valence state of the metal species was indicated by X-ray photoelectron spectroscopy study and a strong electronic effect was found in the NiSe2-CoSe2 catalyst system compared to their counterparts. As a result, NiSe2-CoSe2 exhibited high catalytic performance with a low overpotential of 250 mV to reach 10 mA·cm-2 for OER in the alkaline solution. Furthermore, high catalytic stability and catalytic kinetics were also observed. The superior performance can be attributed to the high valence states of Ni and Co and their strong synergetic coupling effect between the nanorods and nanoparticles, which could accelerate the charge transfer and offer abundant electrocatalytic active sites. The current work offers an efficient hetero-structure catalyst system for OER, and the results are helpful for the catalysis understanding.
Hetero-structure induced high performance catalyst for oxygen evolution reaction (OER) in the water splitting reaction has received increased attention. Herein, we demonstrated a novel catalyst system of NiSe2-CoSe2 consisting of nanorods and nanoparticles for the efficient OER in the alkaline electrolyte. This catalyst system can be easily fabricated via a low-temperature selenization of the solvothermal synthesized NiCo(OH)x precursor and the unique morphology of hybrid nanorods and nanoparticles was found by the electron microscopy analysis. The high valence state of the metal species was indicated by X-ray photoelectron spectroscopy study and a strong electronic effect was found in the NiSe2-CoSe2 catalyst system compared to their counterparts. As a result, NiSe2-CoSe2 exhibited high catalytic performance with a low overpotential of 250 mV to reach 10 mA·cm-2 for OER in the alkaline solution. Furthermore, high catalytic stability and catalytic kinetics were also observed. The superior performance can be attributed to the high valence states of Ni and Co and their strong synergetic coupling effect between the nanorods and nanoparticles, which could accelerate the charge transfer and offer abundant electrocatalytic active sites. The current work offers an efficient hetero-structure catalyst system for OER, and the results are helpful for the catalysis understanding.
2022, 41(1): 220102
doi: 10.14102/j.cnki.0254-5861.2021-0039
Abstract:
The rational construction of a high-efficiency step-scheme heterojunctions is an effective strategy to accelerate the photocatalytic H2. Unfortunately, the variant energy-level matching between two different semiconductor confers limited the photocatalytic performance. Herein, a newfangled graphitic-carbon nitride (g-C3N4) based isotype step-scheme heterojunction, which consists of sulfur-doped and defective active sites in one microstructural unit, is successfully developed by in-situ polymerizing N, N-dimethyl-formamide (DMF) and urea, accompanied by sulfur (S) powder. Therein, the polymerization between the amino groups of DMF and the amide group of urea endows the formation of rich defects. The propulsive integration of S-dopants contributes to the excellent fluffiness and dispersibility of lamellar g-C3N4. Moreover, the developed heterojunction exhibits a significantly enlarged surface area, thus leading to the more exposed catalytically active sites. Most importantly, the simultaneous introduction of S-doping and defects in the units of g-C3N4 also results in a significant improvement in the separation, transfer and recombination efficiency of photo-excited electron-hole pairs. Therefore, the resulting isotype step-scheme heterojunction possesses a superior photocatalytic H2 evolution activity in comparison with pristine g-C3N4. The newly afforded metal-free isotype step-scheme heterojunction in this work will supply a new insight into coupling strategies of heteroatoms doping and defect engineering for various photocatalytic systems.
The rational construction of a high-efficiency step-scheme heterojunctions is an effective strategy to accelerate the photocatalytic H2. Unfortunately, the variant energy-level matching between two different semiconductor confers limited the photocatalytic performance. Herein, a newfangled graphitic-carbon nitride (g-C3N4) based isotype step-scheme heterojunction, which consists of sulfur-doped and defective active sites in one microstructural unit, is successfully developed by in-situ polymerizing N, N-dimethyl-formamide (DMF) and urea, accompanied by sulfur (S) powder. Therein, the polymerization between the amino groups of DMF and the amide group of urea endows the formation of rich defects. The propulsive integration of S-dopants contributes to the excellent fluffiness and dispersibility of lamellar g-C3N4. Moreover, the developed heterojunction exhibits a significantly enlarged surface area, thus leading to the more exposed catalytically active sites. Most importantly, the simultaneous introduction of S-doping and defects in the units of g-C3N4 also results in a significant improvement in the separation, transfer and recombination efficiency of photo-excited electron-hole pairs. Therefore, the resulting isotype step-scheme heterojunction possesses a superior photocatalytic H2 evolution activity in comparison with pristine g-C3N4. The newly afforded metal-free isotype step-scheme heterojunction in this work will supply a new insight into coupling strategies of heteroatoms doping and defect engineering for various photocatalytic systems.
2022, 41(1): 220103
doi: 10.14102/j.cnki.0254-5861.2021-0046
Abstract:
Producing chemical fuels from sunlight enables a sustainable way for energy consumption. Among various solar fuel generation approaches, photocatalytic CO2 reduction has the advantages of simple structure, mild reaction condition, directly reducing carbon emissions, etc. However, most of the current photocatalytic systems can only absorb the UV-visible spectrum of solar light. Therefore, finding a way to utilize infrared light in the photocatalytic system has attracted more and more attention. Here, a Z-scheme In2S3-TiO2 was constructed for CO2 reduction under concentrated natural sunlight. The infrared light was used to create a high-temperature environment for photocatalytic reactions. The evolution rates of H2, CO, and C2H5OH reached 262.2, 73.9, and 27.56 µmol·h-1·g-1, respectively, with an overall solar to fuels efficiency of 0.002%. This work provides a composite photocatalyst towards the utilization of full solar light spectrum, and could promote the research on photocatalytic CO2 reduction.
Producing chemical fuels from sunlight enables a sustainable way for energy consumption. Among various solar fuel generation approaches, photocatalytic CO2 reduction has the advantages of simple structure, mild reaction condition, directly reducing carbon emissions, etc. However, most of the current photocatalytic systems can only absorb the UV-visible spectrum of solar light. Therefore, finding a way to utilize infrared light in the photocatalytic system has attracted more and more attention. Here, a Z-scheme In2S3-TiO2 was constructed for CO2 reduction under concentrated natural sunlight. The infrared light was used to create a high-temperature environment for photocatalytic reactions. The evolution rates of H2, CO, and C2H5OH reached 262.2, 73.9, and 27.56 µmol·h-1·g-1, respectively, with an overall solar to fuels efficiency of 0.002%. This work provides a composite photocatalyst towards the utilization of full solar light spectrum, and could promote the research on photocatalytic CO2 reduction.
2022, 41(1): 220104
doi: 10.14102/j.cnki.0254-5861.2021-0050
Abstract:
Graphene coating is commonly used to improve the performance of electrode materials, while its steric hindrance effect hampers fast ion transport with compromised rate capability. Herein, a unique single-walled carbon nanotubes (SWNTs) coating layer, as an alternative to graphene, has been developed to improve the battery behavior of iron-based anodes. Benefiting from the structure merits of mesoporous SWNTs layer for fast electron/ion transport and hollow Fe3O4 for volume accommodation, as-prepared Fe3O4@SWNTs exhibited excellent lithium storage performance. It delivers a high capacity, excellent rate capability, and long lifespan with capacities of 582 mA·h·g-1 at 5 A·g-1 and 408 mA·h·g-1 at 8 A·g-1 remained after 1000 cycles. Such performance is better than graphene-coated Fe3O4 and other SWNT-Fe3O4 architectures. Besides, SWNTs coating is also used to improve the sodium and potassium storage performance of FeSe2. The kinetics analysis and ex-situ experiment further reveal the effect of SWNTs coating for fast electron/ion transfer kinetics and good structure stability, thus leading to the superior performance of SWNTs-coated composites.
Graphene coating is commonly used to improve the performance of electrode materials, while its steric hindrance effect hampers fast ion transport with compromised rate capability. Herein, a unique single-walled carbon nanotubes (SWNTs) coating layer, as an alternative to graphene, has been developed to improve the battery behavior of iron-based anodes. Benefiting from the structure merits of mesoporous SWNTs layer for fast electron/ion transport and hollow Fe3O4 for volume accommodation, as-prepared Fe3O4@SWNTs exhibited excellent lithium storage performance. It delivers a high capacity, excellent rate capability, and long lifespan with capacities of 582 mA·h·g-1 at 5 A·g-1 and 408 mA·h·g-1 at 8 A·g-1 remained after 1000 cycles. Such performance is better than graphene-coated Fe3O4 and other SWNT-Fe3O4 architectures. Besides, SWNTs coating is also used to improve the sodium and potassium storage performance of FeSe2. The kinetics analysis and ex-situ experiment further reveal the effect of SWNTs coating for fast electron/ion transfer kinetics and good structure stability, thus leading to the superior performance of SWNTs-coated composites.
2022, 41(1): 220104
doi: 10.14102/j.cnki.0254-5861.2021-0057
Abstract:
Photocatalytic hydrogen evolution can convert intermittent and dispersive solar energy into hydrogen with high energy density, which is expected to fundamentally solve the problems of environmental pollution and energy shortages. In this experiment, the performance of the catalyst is modified by introducing cocatalyst and morphology control. Ni(OH)2 nanoflowers are used as substrates to derive nanoplate stack Ni2P by high-temperature phosphating method, and a great many of CeO2 nanoparticles are anchored in the Ni2P. This unique 3D/0D combination effectively inhibits the agglomeration of CeO2 nanoparticles and shortens the electron transfer path. Secondly, the introduction of metal-like performance of Ni2P broadens the light absorption range of the catalyst and reduces the overpotential of the catalyst, which is a key factor in enhancing the catalytic activity. The design ideas of this experiment have reference significance for the design of efficient and environmentally friendly photocatalysts.
Photocatalytic hydrogen evolution can convert intermittent and dispersive solar energy into hydrogen with high energy density, which is expected to fundamentally solve the problems of environmental pollution and energy shortages. In this experiment, the performance of the catalyst is modified by introducing cocatalyst and morphology control. Ni(OH)2 nanoflowers are used as substrates to derive nanoplate stack Ni2P by high-temperature phosphating method, and a great many of CeO2 nanoparticles are anchored in the Ni2P. This unique 3D/0D combination effectively inhibits the agglomeration of CeO2 nanoparticles and shortens the electron transfer path. Secondly, the introduction of metal-like performance of Ni2P broadens the light absorption range of the catalyst and reduces the overpotential of the catalyst, which is a key factor in enhancing the catalytic activity. The design ideas of this experiment have reference significance for the design of efficient and environmentally friendly photocatalysts.
2022, 41(1): 220101
doi: 10.14102/j.cnki.0254-5861.2021-0027
Abstract:
Photoabsorption charge separation/transfer and surface reaction are the three main factors influencing the efficiency of photocatalysis. Band structure engineering has been extensively applied to improve the light absorption of photocatalysts, however, most of the developed photocatalysts still suffer from low photocatalytic performance due to the limited active site(s) and fast recombination of photogenerated charge carriers. In this work, atomically dispersed main group magnesium (Mg) is introduced onto CdS monodispersed nanospheres, which greatly enhances the photocatalytic hydrogen evolution reaction. The photocatalytic hydrogen evolution reaction rate reaches 30.6 mmol·gcatalyst-1·h-1, which is about 11.8 and 2.5 times that of pure CdS and Pt (2 wt.%)-CdS. The atomically dispersed Mg on CdS acts as an electron sink to trap photogenerated electrons, and at the same time, greatly reduces the Gibbs free energy of hydrogen evolution reaction (HER) and accelerates HER.
Photoabsorption charge separation/transfer and surface reaction are the three main factors influencing the efficiency of photocatalysis. Band structure engineering has been extensively applied to improve the light absorption of photocatalysts, however, most of the developed photocatalysts still suffer from low photocatalytic performance due to the limited active site(s) and fast recombination of photogenerated charge carriers. In this work, atomically dispersed main group magnesium (Mg) is introduced onto CdS monodispersed nanospheres, which greatly enhances the photocatalytic hydrogen evolution reaction. The photocatalytic hydrogen evolution reaction rate reaches 30.6 mmol·gcatalyst-1·h-1, which is about 11.8 and 2.5 times that of pure CdS and Pt (2 wt.%)-CdS. The atomically dispersed Mg on CdS acts as an electron sink to trap photogenerated electrons, and at the same time, greatly reduces the Gibbs free energy of hydrogen evolution reaction (HER) and accelerates HER.
2022, 41(1): 220105
doi: 10.14102/j.cnki.0254-5861.2021-0020
Abstract:
Photoelectrochemical (PEC) water splitting is an effective strategy to convert solar energy into clean and renewable hydrogen energy. In order to carry out effective PEC conversion, researchers have conducted a lot of exploration and developed a variety of semiconductors suitable for PEC water splitting. Among them, metal oxides stand out due to their higher stability. Compared with traditional oxide semiconductors, ferrite-based photoelectrodes have the advantages of low cost, small band gap, and good stability. Interestingly, due to the unique characteristics of ferrite, most of them have various tunable features, which will be more conducive to the development of efficient PEC electrode. However, this complex metal oxide is also troubled by severe charge recombination and low carrier transport efficiency, resulting in lower conversion efficiency compared to theoretical value. Based on this, this article reviews the structure, preparation methods, characteristics and modification strategies of various common ferrites. In addition, we analyzed the future research direction of ferrite for PEC water splitting, and looked forward to the development of more efficient catalysts.
Photoelectrochemical (PEC) water splitting is an effective strategy to convert solar energy into clean and renewable hydrogen energy. In order to carry out effective PEC conversion, researchers have conducted a lot of exploration and developed a variety of semiconductors suitable for PEC water splitting. Among them, metal oxides stand out due to their higher stability. Compared with traditional oxide semiconductors, ferrite-based photoelectrodes have the advantages of low cost, small band gap, and good stability. Interestingly, due to the unique characteristics of ferrite, most of them have various tunable features, which will be more conducive to the development of efficient PEC electrode. However, this complex metal oxide is also troubled by severe charge recombination and low carrier transport efficiency, resulting in lower conversion efficiency compared to theoretical value. Based on this, this article reviews the structure, preparation methods, characteristics and modification strategies of various common ferrites. In addition, we analyzed the future research direction of ferrite for PEC water splitting, and looked forward to the development of more efficient catalysts.
