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2023 Volume 42 Issue 12
2023, 42(12): 100170
doi: 10.1016/j.cjsc.2023.100170
Abstract:
High methane conversion (1.1 mmol/h) and C2 selectivity (ca. 90%) were achieved simultaneously on Au60s/TiO2 for photocatalytic OCM. The enhanced activity was attributed to the introduction of Au co-catalyst, which played multi-functions roles: efficient hole acceptor, methane adsorption and activation site, and C–C coupling center. This work underscores the essential role of multifunctional co-catalysts, delving deeply into the structure-activity relationship through a synergistic combination of experimental and theoretical analysis. It is poised to serve as a significant milestone to inspire researchers in the field of photocatalytic OCM and beyond.
High methane conversion (1.1 mmol/h) and C2 selectivity (ca. 90%) were achieved simultaneously on Au60s/TiO2 for photocatalytic OCM. The enhanced activity was attributed to the introduction of Au co-catalyst, which played multi-functions roles: efficient hole acceptor, methane adsorption and activation site, and C–C coupling center. This work underscores the essential role of multifunctional co-catalysts, delving deeply into the structure-activity relationship through a synergistic combination of experimental and theoretical analysis. It is poised to serve as a significant milestone to inspire researchers in the field of photocatalytic OCM and beyond.
2023, 42(12): 100173
doi: 10.1016/j.cjsc.2023.100173
Abstract:
In the past few years, environmental and energy challenges arising from extensive burning of fossil fuels and CO2 emission have become the increasingly severe issue. One effective solution to address these problems is the reduction of CO2 into valuable solar fuels such as CO, CH4, and HCO2H through the semiconductor-based photocatalysis technology. Metal halide perovskites quantum dots (MHPs QDs) represent a new generation of photosensitizers that possess excellent photoelectric properties and have been attracting enormous attention in the field of photocatalytic CO2 reduction. This review provides a concise introduction on different types and preparation methods of MHPs QDs and discusses the specific applications especially photocatalytic CO2 reduction mechanism of MHPs QDs. Furthermore, future opportunities and challenges for constructing high-performance MHPs QDs-based photocatalysts are further elucidated. We anticipate that our review could provide enriched information on the photocatalytic application of MHPs QDs toward solar-to-fuel conversion.
In the past few years, environmental and energy challenges arising from extensive burning of fossil fuels and CO2 emission have become the increasingly severe issue. One effective solution to address these problems is the reduction of CO2 into valuable solar fuels such as CO, CH4, and HCO2H through the semiconductor-based photocatalysis technology. Metal halide perovskites quantum dots (MHPs QDs) represent a new generation of photosensitizers that possess excellent photoelectric properties and have been attracting enormous attention in the field of photocatalytic CO2 reduction. This review provides a concise introduction on different types and preparation methods of MHPs QDs and discusses the specific applications especially photocatalytic CO2 reduction mechanism of MHPs QDs. Furthermore, future opportunities and challenges for constructing high-performance MHPs QDs-based photocatalysts are further elucidated. We anticipate that our review could provide enriched information on the photocatalytic application of MHPs QDs toward solar-to-fuel conversion.
2023, 42(12): 100194
doi: 10.1016/j.cjsc.2023.100194
Abstract:
A specific type S-scheme photocatalyst CeO2@N-GO/g-C3N4 was successfully synthesized, resulting in a 2-mercaptobenzothiazole (MBT) degradation rate of 100%, which is more than twice that of g-C3N4 and CeO2. The improved degradation performance can be attributed to the introduction of N-graphene oxide (N-GO), which facilitates the electron transfer. Additionally, the unique Ce4+ → Ce3+ conversion property enhances the charge carrier utilization, and thereby the photocatalytic activity. Furthermore, theoretical calculations suggest the formation of an interfacial internal electric field (IEF) formed between CeO2 (the (200) and (311) planes) and g-C3N4 (the (002) plane) to enhance the delocalization of the charge carriers. Moreover, various photoelectrocheical analyses are employed for the in-depth mechanism on MBT degradation and IEF-induced S-scheme over CeO2@N-GO/g-C3N4, where the differential charge proves the electron transfer path from CeO2 to g-C3N4 that significantly prolongs its lifetime. The radical capture and electron spin resonance (ESR) results proved the existence of the active species of ·OH, ·O2-, and h+ in the S-scheme photocatalytic system.
A specific type S-scheme photocatalyst CeO2@N-GO/g-C3N4 was successfully synthesized, resulting in a 2-mercaptobenzothiazole (MBT) degradation rate of 100%, which is more than twice that of g-C3N4 and CeO2. The improved degradation performance can be attributed to the introduction of N-graphene oxide (N-GO), which facilitates the electron transfer. Additionally, the unique Ce4+ → Ce3+ conversion property enhances the charge carrier utilization, and thereby the photocatalytic activity. Furthermore, theoretical calculations suggest the formation of an interfacial internal electric field (IEF) formed between CeO2 (the (200) and (311) planes) and g-C3N4 (the (002) plane) to enhance the delocalization of the charge carriers. Moreover, various photoelectrocheical analyses are employed for the in-depth mechanism on MBT degradation and IEF-induced S-scheme over CeO2@N-GO/g-C3N4, where the differential charge proves the electron transfer path from CeO2 to g-C3N4 that significantly prolongs its lifetime. The radical capture and electron spin resonance (ESR) results proved the existence of the active species of ·OH, ·O2-, and h+ in the S-scheme photocatalytic system.
2023, 42(12): 100198
doi: 10.1016/j.cjsc.2023.100198
Abstract:
Interface engineering of photocatalysts is an effective way to enhance their photocatalytic activity. In this work, the MOF-on-MOF strategy was used to construct the ZIF-9(Co)/Cu3BTC2 photocatalyst in situ. Moreover, graphdiyne, possessing an inherent capability to facilitate rapid electron transfer at the interface, has been introduced into the ZIF-9(Co)/Cu3BTC2 interface to regulate the interfacial carrier migration. The photogenerated carrier transfer capability has been significantly enhanced by the interfacial synergy, while retaining the original active sites and high specific surface area. The exceptional efficiency performance of the composite catalyst under identical conditions could be attributed to the following two key factors: (i) The interfacial S-scheme heterojunction in ZIF-9(Co)/Cu3BTC2 provides the composite catalyst with strong reduction activity, facilitating the involvement of additional electrons in the reduction reaction through bended bands and an internal electric field. (ii) Carrier dynamics analysis shows that graphdiyne, as an electron transport layer, accelerates the charge migration rate at the S-scheme heterojunction interface through the electron relay effect. The incorporation of graphdiyne greatly improves the catalytic activity of MOFs and also demonstrates the great potential of graphdiyne in photocatalysis. This work provides a feasible idea for the interface engineering design of graphdiyne in photocatalysts.
Interface engineering of photocatalysts is an effective way to enhance their photocatalytic activity. In this work, the MOF-on-MOF strategy was used to construct the ZIF-9(Co)/Cu3BTC2 photocatalyst in situ. Moreover, graphdiyne, possessing an inherent capability to facilitate rapid electron transfer at the interface, has been introduced into the ZIF-9(Co)/Cu3BTC2 interface to regulate the interfacial carrier migration. The photogenerated carrier transfer capability has been significantly enhanced by the interfacial synergy, while retaining the original active sites and high specific surface area. The exceptional efficiency performance of the composite catalyst under identical conditions could be attributed to the following two key factors: (i) The interfacial S-scheme heterojunction in ZIF-9(Co)/Cu3BTC2 provides the composite catalyst with strong reduction activity, facilitating the involvement of additional electrons in the reduction reaction through bended bands and an internal electric field. (ii) Carrier dynamics analysis shows that graphdiyne, as an electron transport layer, accelerates the charge migration rate at the S-scheme heterojunction interface through the electron relay effect. The incorporation of graphdiyne greatly improves the catalytic activity of MOFs and also demonstrates the great potential of graphdiyne in photocatalysis. This work provides a feasible idea for the interface engineering design of graphdiyne in photocatalysts.
2023, 42(12): 100201
doi: 10.1016/j.cjsc.2023.100201
Abstract:
The practical application of hexagonal ZnIn2S4 (ZIS) as a visible-light photocatalyst for hydrogen (H2) production is hindered by rapid internal charge recombination. In this study, we successfully synthesized Cu2CoSnS4 (CCTS) nanocrystals and loaded them onto the surface of ZIS nanosheets to create a p-n heterojunction photocatalyst. The optimized Cu2CoSnS4/ZnIn2S4 (CCTS/ZIS) heterojunction exhibited a significantly higher visible-light photocatalytic H2 evolution rate of 4.90 mmol·g-1·h-1 compared to ZIS and CCTS alone. The enhanced photocatalytic efficiency was attributed to improved electron transfer and charge separation at the heterojunction interface. The formation of p-n heterojunction facilitated the accumulation of valence band electrons in ZIS and conduction band holes in CCTS, effectively suppressing the recombination of photogenerated electrons and holes. Theoretical calculations, spectroscopic, and photoelectrochemical characterizations supported the findings. This work presents a promising approach for designing efficient p-n heterojunction semiconductor photocatalysts for practical applications in visible-light-driven hydrogen evolution.
The practical application of hexagonal ZnIn2S4 (ZIS) as a visible-light photocatalyst for hydrogen (H2) production is hindered by rapid internal charge recombination. In this study, we successfully synthesized Cu2CoSnS4 (CCTS) nanocrystals and loaded them onto the surface of ZIS nanosheets to create a p-n heterojunction photocatalyst. The optimized Cu2CoSnS4/ZnIn2S4 (CCTS/ZIS) heterojunction exhibited a significantly higher visible-light photocatalytic H2 evolution rate of 4.90 mmol·g-1·h-1 compared to ZIS and CCTS alone. The enhanced photocatalytic efficiency was attributed to improved electron transfer and charge separation at the heterojunction interface. The formation of p-n heterojunction facilitated the accumulation of valence band electrons in ZIS and conduction band holes in CCTS, effectively suppressing the recombination of photogenerated electrons and holes. Theoretical calculations, spectroscopic, and photoelectrochemical characterizations supported the findings. This work presents a promising approach for designing efficient p-n heterojunction semiconductor photocatalysts for practical applications in visible-light-driven hydrogen evolution.
2023, 42(12): 100202
doi: 10.1016/j.cjsc.2023.100202
Abstract:
Harnessing solar energy for photocatalytic hydrogen peroxide (H2O2) synthesis represents a pinnacle of environmentally-sensitive and sustainable methodologies. While single-layer crystalline triazine-based organic frameworks (CTFs) are known for their prodigious photocatalytic potential in H2O2 generation, ramifications of the connecting group within the triazine ring (TR) on underlying photocatalytic mechanism warrant deeper exploration. In this study, we simulate three distinct CTFs characterized by different TR linkers: CTF-1 (benzene group (BG)), CTF-2 (horizontally-oriented naphthyl group (NGH)), and CTF-DCN (vertically-oriented naphthyl group (NGV)). These diverse TR linkers profoundly modulate the absorption band edge of CTFs, subsequently dictating the orientation and constitution of the frontier orbitals. Such modulation plays a decisive role in determining the requisite energy for photoexcitation in CTFs, orchestrating the generation and distribution of photo-induced electrons and holes. Remarkably, the NGV linkage imparts CTF-DCN with unparalleled light absorption, superior charge separation efficiency, and the lowest energy barrier for associated reactions. Through this investigation, we illuminate the pivotal influence of TR linkers in sculpting the photocatalytic dynamics of CTFs, providing fresh perspectives for architecting CTFs with amplified photocatalytic prowess in H2O2 synthesis.
Harnessing solar energy for photocatalytic hydrogen peroxide (H2O2) synthesis represents a pinnacle of environmentally-sensitive and sustainable methodologies. While single-layer crystalline triazine-based organic frameworks (CTFs) are known for their prodigious photocatalytic potential in H2O2 generation, ramifications of the connecting group within the triazine ring (TR) on underlying photocatalytic mechanism warrant deeper exploration. In this study, we simulate three distinct CTFs characterized by different TR linkers: CTF-1 (benzene group (BG)), CTF-2 (horizontally-oriented naphthyl group (NGH)), and CTF-DCN (vertically-oriented naphthyl group (NGV)). These diverse TR linkers profoundly modulate the absorption band edge of CTFs, subsequently dictating the orientation and constitution of the frontier orbitals. Such modulation plays a decisive role in determining the requisite energy for photoexcitation in CTFs, orchestrating the generation and distribution of photo-induced electrons and holes. Remarkably, the NGV linkage imparts CTF-DCN with unparalleled light absorption, superior charge separation efficiency, and the lowest energy barrier for associated reactions. Through this investigation, we illuminate the pivotal influence of TR linkers in sculpting the photocatalytic dynamics of CTFs, providing fresh perspectives for architecting CTFs with amplified photocatalytic prowess in H2O2 synthesis.
2023, 42(12): 100204
doi: 10.1016/j.cjsc.2023.100204
Abstract:
Photocatalytic hydrogen evolution through water splitting holds tremendous promise for converting solar energy into a clean and renewable fuel source. However, the efficiency of photocatalysis is often hindered by poor light absorption, insufficient charge separation, and slow reaction kinetics of the photocatalysts. In this study, we designed and synthesized a novel S-scheme heterojunction comprising Ti3C2 MXene, CdS nanorods, and nitrogen-doped carbon coated Cu2O (Cu2O@NC) core-shell nanoparticles. Ti3C2 MXene as a cocatalyst enhances the light absorption and charge transfer of CdS nanorods. Simultaneously, the core-shell Cu2O@NC nanoparticles establish a pathway for transferring photogenerated electrons and create a favorable band alignment for efficient hydrogen evolution. The synergistic effects of Ti3C2 MXene and Cu2O@NC on CdS nanorods result in multiple charge transfer channels and improved photocatalytic performance. The optimal hydrogen evolution rate of the Ti3C2-CdS-Cu2O@NC S-scheme heterojunction photocatalyst is 7.4 times higher than that of pure CdS. Experimental techniques and DFT calculations were employed to explore the structure, morphology, optical properties, charge dynamics, and band structure of the heterojunction. The results revealed that the S-scheme mechanism effectively suppresses the recombination of photogenerated carriers and facilitates the separation and migration of photogenerated electrons and holes to the reaction sites. Furthermore, Ti3C2 MXene provides abundant active sites essential for accelerating the surface H2-evolution reaction kinetics. The Cu2O@NC core-shell nanoparticles with a large surface area and high stability are closely adhered to CdS nanorods and establish an S-scheme internal electric field with CdS nanorods to drive charge separation. This investigation provides valuable insights into the rational design of CdS-based photocatalysts, enabling efficient hydrogen production by harnessing the robust kinetic driving force provided by the S-scheme heterojunctions.
Photocatalytic hydrogen evolution through water splitting holds tremendous promise for converting solar energy into a clean and renewable fuel source. However, the efficiency of photocatalysis is often hindered by poor light absorption, insufficient charge separation, and slow reaction kinetics of the photocatalysts. In this study, we designed and synthesized a novel S-scheme heterojunction comprising Ti3C2 MXene, CdS nanorods, and nitrogen-doped carbon coated Cu2O (Cu2O@NC) core-shell nanoparticles. Ti3C2 MXene as a cocatalyst enhances the light absorption and charge transfer of CdS nanorods. Simultaneously, the core-shell Cu2O@NC nanoparticles establish a pathway for transferring photogenerated electrons and create a favorable band alignment for efficient hydrogen evolution. The synergistic effects of Ti3C2 MXene and Cu2O@NC on CdS nanorods result in multiple charge transfer channels and improved photocatalytic performance. The optimal hydrogen evolution rate of the Ti3C2-CdS-Cu2O@NC S-scheme heterojunction photocatalyst is 7.4 times higher than that of pure CdS. Experimental techniques and DFT calculations were employed to explore the structure, morphology, optical properties, charge dynamics, and band structure of the heterojunction. The results revealed that the S-scheme mechanism effectively suppresses the recombination of photogenerated carriers and facilitates the separation and migration of photogenerated electrons and holes to the reaction sites. Furthermore, Ti3C2 MXene provides abundant active sites essential for accelerating the surface H2-evolution reaction kinetics. The Cu2O@NC core-shell nanoparticles with a large surface area and high stability are closely adhered to CdS nanorods and establish an S-scheme internal electric field with CdS nanorods to drive charge separation. This investigation provides valuable insights into the rational design of CdS-based photocatalysts, enabling efficient hydrogen production by harnessing the robust kinetic driving force provided by the S-scheme heterojunctions.
2023, 42(12): 100205
doi: 10.1016/j.cjsc.2023.100205
Abstract:
Atrazine (ATZ), as one of the most extensively employed organochlorine-based herbicides, exhibits persistence and environmental toxicity. Photocatalytic technology based on polymer carbon nitride is regarded as a sustainable and promising approach for the degradation of emerging organic pollutants. Regrettably, the inherent shortcomings of pure carbon nitride greatly limit its practical application. Herein, S-doped carbon nitride was elaborately constructed for efficient degradation of ATZ. The removal efficiency of ATZ by the optimal sample (0.052 min-1) is 3.25 times as that of pure carbon nitride (0.016 min-1). Experiments and DFT calculations show that S doping optimizes electronic structure of carbon nitride, which significantly enhances the spatial separation and transfer efficiency of photogenerated electrons and holes. Moreover, the reactive sites and degradation paths of ATZ were predicted by Fukui function and LC-MS determination. Our work provides an effective approach for the design of efficient photocatalysts to achieve efficient environmental remediation.
Atrazine (ATZ), as one of the most extensively employed organochlorine-based herbicides, exhibits persistence and environmental toxicity. Photocatalytic technology based on polymer carbon nitride is regarded as a sustainable and promising approach for the degradation of emerging organic pollutants. Regrettably, the inherent shortcomings of pure carbon nitride greatly limit its practical application. Herein, S-doped carbon nitride was elaborately constructed for efficient degradation of ATZ. The removal efficiency of ATZ by the optimal sample (0.052 min-1) is 3.25 times as that of pure carbon nitride (0.016 min-1). Experiments and DFT calculations show that S doping optimizes electronic structure of carbon nitride, which significantly enhances the spatial separation and transfer efficiency of photogenerated electrons and holes. Moreover, the reactive sites and degradation paths of ATZ were predicted by Fukui function and LC-MS determination. Our work provides an effective approach for the design of efficient photocatalysts to achieve efficient environmental remediation.
