Environmental pollution and energy shortage has been regarded as the two major challenges because of the rapid development of urbanization and industrialization.Considering these challenges,providing green environment...Environmental pollution and energy shortage has been regarded as the two major challenges because of the rapid development of urbanization and industrialization.Considering these challenges,providing green environment and energy for human beings are pivotal for future sustainable development.Nanostructured catalysts(photocatalysts,thermal catalysts and electrocatalysts)with unique physiochemical properties could offer numerous opportunities to solve these issues of environmental and energetic sustainability.In recent years,significant advances have been made on the synthesis,mechanistic understanding and innovative applications of the new catalysts for environmental and energetic problems.These new catalysts have found wide applications in different fashions.展开更多
Surface plasmon resonance(SPR)of metals may provide a way to improve light absorption and utilization of semiconductors,achieving better solar light conversion and photocatalysis efficiency.This study uses the advanta...Surface plasmon resonance(SPR)of metals may provide a way to improve light absorption and utilization of semiconductors,achieving better solar light conversion and photocatalysis efficiency.This study uses the advantages of SPR in metallic Bi and artificial defects to cooperatively enhance the photocatalytic performance of BiOI.The catalysts were prepared by partial reduction of BiOI to form Bi@defective BiOI,which showed highly enhanced visible photocatalytic activity for NOx removal.The effects of reductant quantity on the photocatalytic performance of Bi@defective BiOI were investigated.The as-prepared photocatalyst(Bi/BiOI-2)using 2 mmol of reductant NaBH4 showed the most efficient visible light photocatalytic activity.This enhanced activity can be ascribed to the synergistic effects of metallic Bi and oxygen vacancies.The electrons from the valence band tend to accumulate at vacancy states;therefore,the increased charge density would cause the adsorbed oxygen to transform more easily into superoxide radicals and,further,into hydroxyl radicals.These radicals are the main active species that oxidize NO into final products.The SPR effect of elemental Bi enables the improvement of visible light absorption efficiency and the promotion of charge carrier separation,which are crucial factors in boosting photocatalysis.NO adsorption and reaction processes on Bi/BiOI-2 were dynamically monitored by in situ infrared spectroscopy(FT-IR).The Bi/BiOI photocatalysis mechanism co-mediated by elemental Bi and oxygen vacancies was proposed based on the analysis of intermediate products and DFT calculations.This present work could provide new insights into the design of high-performance photocatalysts and understanding of the photocatalysis reaction mechanism for air-purification applications.展开更多
Aromatic ring-opening process is well recognized as the rate-determining step for catalytic toluene degradation. In photocatalytic toluene degradation, the toxic intermediates w让h harmful effects may be generated. To...Aromatic ring-opening process is well recognized as the rate-determining step for catalytic toluene degradation. In photocatalytic toluene degradation, the toxic intermediates w让h harmful effects may be generated. To clarify the precise reaction mechanism and control the toxic intermediates generation, a closely combined in situ DRIFTS and DFT calculation is utilized to address these important issues. We construct the BiOCl w让h oxygen vacancies (OVs) and reveal the structure of OVs. The defect level caused by oxygen vacancies could promote the light adsorption and charge separation, which further boosts the activation of ring-opening species and enhances the generation process of free radicals. The reaction energy barriers of four possible ring-opening processes on defective BiOCl (OVBOC) are all declined in comparison with perfect BiOCl (BOC). The existence of oxygen vacancies could smooth the ratedetermining step so the ring-opening efficiency of photocatalytic toluene degradation is highly increased. Most importantly, the methyl species would be further oxidized and tend to open the benzene-ring at benzoic acid on BOC while the ring would be broken at the benzyl alcohol on OVBOC. These results indicate that the toluene degradation pathway is shortened via the surface OVs, which enables the production of radicals with high oxidation capability for the accelerated chain scission of the ring-opening intermediates. Finally, the efficiency of the key ring-opening process could be enormously improved and toxic intermediates are effectively restrained. The present work could provide new insights into the design of high-performance photocatalysts for efficient and safe degradation of VOCs in air.展开更多
Photocatalytic technology has been widely adopted to address the issue of air pollution. The separation of photogenerated carriers and the activation of reactants on catalyst surface are the main factors that affect t...Photocatalytic technology has been widely adopted to address the issue of air pollution. The separation of photogenerated carriers and the activation of reactants on catalyst surface are the main factors that affect the photocatalytic efficiency. Here, the phosphate/potassium(PO_4/K) cofunctionalized carbon nitride(labeled as PO_4-CN-K) was synthesized via a one-step in situ copyrolysis of thiourea and potassium phosphate. The unique electronic structure of PO_4-CN-K could significantly improve the performance of photocatalytic NO purification. The enhanced activity of PO_4-CN-K can be attributed to the promoted activation capacity for O_2, NO and H_2O on the catalyst surface,the decreased of carriers recombination, benefiting from the co-functionalization of phosphate groups on the surface of CN and the construction of K channels between CN layers. The photocatalytic NO conversion pathway is disclosed through time-dependent in situ FT-IR, indicating that PO_4-CN-K can efficiently convert NO molecules into harmless nitrate via the NO→NO+→nitrate/nitrite routes. The research provides a novel strategy to impel the development of photocatalytic technology for efficient air purification.展开更多
文摘Environmental pollution and energy shortage has been regarded as the two major challenges because of the rapid development of urbanization and industrialization.Considering these challenges,providing green environment and energy for human beings are pivotal for future sustainable development.Nanostructured catalysts(photocatalysts,thermal catalysts and electrocatalysts)with unique physiochemical properties could offer numerous opportunities to solve these issues of environmental and energetic sustainability.In recent years,significant advances have been made on the synthesis,mechanistic understanding and innovative applications of the new catalysts for environmental and energetic problems.These new catalysts have found wide applications in different fashions.
基金supported by the National Natural Science Foundation of China(21501016,21777011 and 21822601)the National Key R&D Program of China(2016YFC02047)+2 种基金the Innovative Research Team of Chongqing(CXTDG201602014)the Key Natural Science Foundation of Chongqing(cstc2017jcyj BX0052)the National Ten Thousand Talent Program of China~~
文摘Surface plasmon resonance(SPR)of metals may provide a way to improve light absorption and utilization of semiconductors,achieving better solar light conversion and photocatalysis efficiency.This study uses the advantages of SPR in metallic Bi and artificial defects to cooperatively enhance the photocatalytic performance of BiOI.The catalysts were prepared by partial reduction of BiOI to form Bi@defective BiOI,which showed highly enhanced visible photocatalytic activity for NOx removal.The effects of reductant quantity on the photocatalytic performance of Bi@defective BiOI were investigated.The as-prepared photocatalyst(Bi/BiOI-2)using 2 mmol of reductant NaBH4 showed the most efficient visible light photocatalytic activity.This enhanced activity can be ascribed to the synergistic effects of metallic Bi and oxygen vacancies.The electrons from the valence band tend to accumulate at vacancy states;therefore,the increased charge density would cause the adsorbed oxygen to transform more easily into superoxide radicals and,further,into hydroxyl radicals.These radicals are the main active species that oxidize NO into final products.The SPR effect of elemental Bi enables the improvement of visible light absorption efficiency and the promotion of charge carrier separation,which are crucial factors in boosting photocatalysis.NO adsorption and reaction processes on Bi/BiOI-2 were dynamically monitored by in situ infrared spectroscopy(FT-IR).The Bi/BiOI photocatalysis mechanism co-mediated by elemental Bi and oxygen vacancies was proposed based on the analysis of intermediate products and DFT calculations.This present work could provide new insights into the design of high-performance photocatalysts and understanding of the photocatalysis reaction mechanism for air-purification applications.
基金supported by the National Key R&D Plan(2016YFC02047)the National Natural Science Foundation of China(21822601,21777011,and 21501016)+2 种基金the Innovative Research Team of Chongqing(CXTDG201602014)the Key Natural Science Foundation of Chongqing(cstc2017jcyjBX0052)the Plan for ‘‘National Youth Talents” of the Organization Department of the Central Committee
文摘Aromatic ring-opening process is well recognized as the rate-determining step for catalytic toluene degradation. In photocatalytic toluene degradation, the toxic intermediates w让h harmful effects may be generated. To clarify the precise reaction mechanism and control the toxic intermediates generation, a closely combined in situ DRIFTS and DFT calculation is utilized to address these important issues. We construct the BiOCl w让h oxygen vacancies (OVs) and reveal the structure of OVs. The defect level caused by oxygen vacancies could promote the light adsorption and charge separation, which further boosts the activation of ring-opening species and enhances the generation process of free radicals. The reaction energy barriers of four possible ring-opening processes on defective BiOCl (OVBOC) are all declined in comparison with perfect BiOCl (BOC). The existence of oxygen vacancies could smooth the ratedetermining step so the ring-opening efficiency of photocatalytic toluene degradation is highly increased. Most importantly, the methyl species would be further oxidized and tend to open the benzene-ring at benzoic acid on BOC while the ring would be broken at the benzyl alcohol on OVBOC. These results indicate that the toluene degradation pathway is shortened via the surface OVs, which enables the production of radicals with high oxidation capability for the accelerated chain scission of the ring-opening intermediates. Finally, the efficiency of the key ring-opening process could be enormously improved and toxic intermediates are effectively restrained. The present work could provide new insights into the design of high-performance photocatalysts for efficient and safe degradation of VOCs in air.
基金supported by the National Natural Science Foundation of China (Nos.21822601, 21777011 and 21501016)the Innovative Research Team of Chongqing (No. CXTDG201602014)+1 种基金the Natural Science Foundation of Chongqing (No. cstc2017jcyjBX0052)the Plan for "National Youth36 Talents" of the Organization Department of the Central Committee
文摘Photocatalytic technology has been widely adopted to address the issue of air pollution. The separation of photogenerated carriers and the activation of reactants on catalyst surface are the main factors that affect the photocatalytic efficiency. Here, the phosphate/potassium(PO_4/K) cofunctionalized carbon nitride(labeled as PO_4-CN-K) was synthesized via a one-step in situ copyrolysis of thiourea and potassium phosphate. The unique electronic structure of PO_4-CN-K could significantly improve the performance of photocatalytic NO purification. The enhanced activity of PO_4-CN-K can be attributed to the promoted activation capacity for O_2, NO and H_2O on the catalyst surface,the decreased of carriers recombination, benefiting from the co-functionalization of phosphate groups on the surface of CN and the construction of K channels between CN layers. The photocatalytic NO conversion pathway is disclosed through time-dependent in situ FT-IR, indicating that PO_4-CN-K can efficiently convert NO molecules into harmless nitrate via the NO→NO+→nitrate/nitrite routes. The research provides a novel strategy to impel the development of photocatalytic technology for efficient air purification.
