In this work,a series of BiOBr nanoplates with oxygen vacancies(OVs)were synthesized by a solvothermal method using a water/ethylene glycol solution.The number of OVs and facets of BiOBr were tuned by changing the wat...In this work,a series of BiOBr nanoplates with oxygen vacancies(OVs)were synthesized by a solvothermal method using a water/ethylene glycol solution.The number of OVs and facets of BiOBr were tuned by changing the water/ethylene glycol ratio.Although the role of OVs in photocatalysis has been investigated,the underlying mechanisms of charge transfer and reactant activation remain unknown.To unravel the effect of OVs on the reactant activation and photocatalytic NO oxidation process,in situ diffuse reflectance infrared Fourier transform spectroscopy,so‐called DRIFTS,and theoretical calculations were performed and their results combined.The photocatalytic efficiency of the as‐prepared BiOBr was significantly increased by increasing the amount of OVs.The oxygen vacancies had several effects on the photocatalysts,including the introduction of intermediate energy levels that enhanced light absorption,promoted electron transfer,acted as active sites for catalytic reaction and the activation of oxygen molecules,and facilitated the conversion of the intermediate products to the final product,thus increasing the overall visible light photocatalysis efficiency.The present work provides new insights into the understanding of the role of OVs in photocatalysts and the mechanism of photocatalytic NO oxidation.展开更多
This work unraveled the synergistic effects of crystal structure and oxygen vacancy on the photocatalytic activity of Bi2O3 polymorphs at an atomic level for the first time. The artificial oxygen vacancy is introduced...This work unraveled the synergistic effects of crystal structure and oxygen vacancy on the photocatalytic activity of Bi2O3 polymorphs at an atomic level for the first time. The artificial oxygen vacancy is introduced into α-Bi2O3 and β-Bi2O3 via a facile method to engineer the band structures and transportation of carriers and redox reaction for highly enhanced photocatalysis. After the optimization, the photocatalytic NO removal ratio on defective β-Bi2O3 was increased from 25.2% to 52.0% under visible light irradiation.On defective a-Bi2O3, the NO removal ratio is just increased from 7.3% to 20.1%. The difference in the activity enhancement is associated with the different structure of crystal phase and oxygen vacancy.The density functional theory(DFT) calculation and experimental results confirm that the oxygen vacancy in a-Bi2O3 and β-Bi2O3 could promote the activation of reactants and intermediate as active centers. The crystal structure and oxygen vacancy could synergistically regulate the electrons transfer pathway. On defective β-Bi2O3 with tunnel structure, the reactants activation and charge transfer were more efficient than that on α-Bi2O3 with zigzag-type configuration because the defect structures on the surface of a-Bi2O3 and β-Bi2O3 were different. Moreover, the in situ FT-IR revealed the mechanisms of photocatalytic NO oxidation. The photocatalytic NO conversion pathway on α-Bi2O3 and β-Bi2O3 can be tuned by the different surface defect structures. This work could provide a novel strategy to regulate the photocatalytic activity and conversion pathway via the synergistic effects of crystal structure and oxygen vacancy.展开更多
文摘In this work,a series of BiOBr nanoplates with oxygen vacancies(OVs)were synthesized by a solvothermal method using a water/ethylene glycol solution.The number of OVs and facets of BiOBr were tuned by changing the water/ethylene glycol ratio.Although the role of OVs in photocatalysis has been investigated,the underlying mechanisms of charge transfer and reactant activation remain unknown.To unravel the effect of OVs on the reactant activation and photocatalytic NO oxidation process,in situ diffuse reflectance infrared Fourier transform spectroscopy,so‐called DRIFTS,and theoretical calculations were performed and their results combined.The photocatalytic efficiency of the as‐prepared BiOBr was significantly increased by increasing the amount of OVs.The oxygen vacancies had several effects on the photocatalysts,including the introduction of intermediate energy levels that enhanced light absorption,promoted electron transfer,acted as active sites for catalytic reaction and the activation of oxygen molecules,and facilitated the conversion of the intermediate products to the final product,thus increasing the overall visible light photocatalysis efficiency.The present work provides new insights into the understanding of the role of OVs in photocatalysts and the mechanism of photocatalytic NO oxidation.
基金supported by the National Natural Science Foundation of China (21822601, 21777011, and 21501016)the Innovative Research Team of Chongqing (CXQT19023)+2 种基金the Natural Science Foundation of Chongqing (cstc2017jcyj BX0052)the Plan for “National Youth Talents” of the Organization Department of the Central Committee, the Innovative Project from Chongqing Technology and Business University (yjscxx2019-101-67)the Fundamental Research Funds for the Central Universities (ZYGX2019Z021)。
文摘This work unraveled the synergistic effects of crystal structure and oxygen vacancy on the photocatalytic activity of Bi2O3 polymorphs at an atomic level for the first time. The artificial oxygen vacancy is introduced into α-Bi2O3 and β-Bi2O3 via a facile method to engineer the band structures and transportation of carriers and redox reaction for highly enhanced photocatalysis. After the optimization, the photocatalytic NO removal ratio on defective β-Bi2O3 was increased from 25.2% to 52.0% under visible light irradiation.On defective a-Bi2O3, the NO removal ratio is just increased from 7.3% to 20.1%. The difference in the activity enhancement is associated with the different structure of crystal phase and oxygen vacancy.The density functional theory(DFT) calculation and experimental results confirm that the oxygen vacancy in a-Bi2O3 and β-Bi2O3 could promote the activation of reactants and intermediate as active centers. The crystal structure and oxygen vacancy could synergistically regulate the electrons transfer pathway. On defective β-Bi2O3 with tunnel structure, the reactants activation and charge transfer were more efficient than that on α-Bi2O3 with zigzag-type configuration because the defect structures on the surface of a-Bi2O3 and β-Bi2O3 were different. Moreover, the in situ FT-IR revealed the mechanisms of photocatalytic NO oxidation. The photocatalytic NO conversion pathway on α-Bi2O3 and β-Bi2O3 can be tuned by the different surface defect structures. This work could provide a novel strategy to regulate the photocatalytic activity and conversion pathway via the synergistic effects of crystal structure and oxygen vacancy.
