Bi2MoO6,a typical Bi-based photocatalyst,has received increasing interests and been widely applied in various fields.However,the visible light photocatalytic activity of Bi2MoO6 is still restricted by some obstacles,s...Bi2MoO6,a typical Bi-based photocatalyst,has received increasing interests and been widely applied in various fields.However,the visible light photocatalytic activity of Bi2MoO6 is still restricted by some obstacles,such as limited photo-response and low charge separation efficiency.In this work,we developed a facile method to introduce artificial oxygen vacancy into Bi2MoO6 microspheres,which could effectively address these problems and realize highly efficient visible light photocatalysis.The experimental and theoretical methods were combined to explore the effects of oxygen vacancy on the electronic structure,photocatalytic activity and the reaction mechanism toward NO removal.The results showed that the addition of NaBH4 during catalyst preparation induced the formation of oxygen vacancy in Bi2MoO6,which plays a significant role in extending the visible light absorption of Bi2MoO6.The visible light photocatalytic activity of Bi2MoO6 with oxygen vacancy was obviously enhanced with a NO removal ratio of 43.5%,in contrast to that of 25.0%with the pristine Bi2MoO6.This can be attributed to the oxygen vacancy that creates a defect energy level in the band gap of Bi2MoO6,thus facilitating the charge separation and transfer processes.Hence,more reactive radicals were generated and participated in the photocatalytic NO oxidation reaction.The in situ FT-IR was used to dynamically monitor the photocatalytic NO oxidation process.The reaction intermediates were observed and the adsorption-reaction mechanism was proposed.It was found that the reaction mechanism was unchanged by introducing the oxygen vacancy in Bi2MoO6.This work could provide new insights into the understanding of the oxygen vacancy in photocatalysis and gas-phase photocatalytic reaction mechanism.展开更多
Both MnOx and g‐C3N4 have been proved to be active in the catalytic oxidation of NO,and their individual mechanisms for catalytic NO conversion have also been investigated.However,the mechanism of photo‐thermal cata...Both MnOx and g‐C3N4 have been proved to be active in the catalytic oxidation of NO,and their individual mechanisms for catalytic NO conversion have also been investigated.However,the mechanism of photo‐thermal catalysis of the MnOx/g‐C3N4 composite remains unresolved.In this paper,MnOx/g‐C3N4 catalysts with different molar ratios were synthesized by the precipitation approach at room temperature.The as‐prepared catalysts exhibit excellent synergistic photo‐thermal catalytic performance towards the purification of NO in air.The MnOx/g‐C3N4 catalysts contain MnOx with different valence states on the surface of g‐C3N4.The thermal catalytic reaction for NO oxidation on MnOx and the photo‐thermal catalytic reaction on 1:5 MnOx/g‐C3N4 were investigated by in situ diffuse reflectance infrared Fourier transform spectroscopy(in situ DRIFTS).The results show that light exerted a weak effect on NO oxidation over MnOx,and it exerted a positive synergistic effect on NO conversion over 1:5 MnOx/g‐C3N4.A synergistic photo‐thermal catalytic cycle of NO oxidation on MnOx/g‐C3N4 is proposed.Specifically,photo‐generated electrons(e?)are transferred to MnOx and participate in the synergistic photo‐thermal reduction cycle(Mn4+→Mn3+→Mn2+).The reverse cycle(Mn2+→Mn3+→Mn4+)can regenerate the active oxygen vacancy sites and inject electrons into the g‐C3N4 hole(h+).The active oxygen(O?)was generated in the redox cycles among manganese species(Mn4+/Mn3+/Mn2+)and could oxidize the intermediates(NOH and N2O2?)to final products(NO2?and NO3?).This paper can provide insightful guidance for the development of better catalysts for NOx purification.展开更多
基金supported by the National Natural Science Foundation of China(21501016,51501024,51871037 and 21822601)the Fundamental Research Funds for the Central Universities(2018CDQYCL0027)~~
文摘Bi2MoO6,a typical Bi-based photocatalyst,has received increasing interests and been widely applied in various fields.However,the visible light photocatalytic activity of Bi2MoO6 is still restricted by some obstacles,such as limited photo-response and low charge separation efficiency.In this work,we developed a facile method to introduce artificial oxygen vacancy into Bi2MoO6 microspheres,which could effectively address these problems and realize highly efficient visible light photocatalysis.The experimental and theoretical methods were combined to explore the effects of oxygen vacancy on the electronic structure,photocatalytic activity and the reaction mechanism toward NO removal.The results showed that the addition of NaBH4 during catalyst preparation induced the formation of oxygen vacancy in Bi2MoO6,which plays a significant role in extending the visible light absorption of Bi2MoO6.The visible light photocatalytic activity of Bi2MoO6 with oxygen vacancy was obviously enhanced with a NO removal ratio of 43.5%,in contrast to that of 25.0%with the pristine Bi2MoO6.This can be attributed to the oxygen vacancy that creates a defect energy level in the band gap of Bi2MoO6,thus facilitating the charge separation and transfer processes.Hence,more reactive radicals were generated and participated in the photocatalytic NO oxidation reaction.The in situ FT-IR was used to dynamically monitor the photocatalytic NO oxidation process.The reaction intermediates were observed and the adsorption-reaction mechanism was proposed.It was found that the reaction mechanism was unchanged by introducing the oxygen vacancy in Bi2MoO6.This work could provide new insights into the understanding of the oxygen vacancy in photocatalysis and gas-phase photocatalytic reaction mechanism.
文摘Both MnOx and g‐C3N4 have been proved to be active in the catalytic oxidation of NO,and their individual mechanisms for catalytic NO conversion have also been investigated.However,the mechanism of photo‐thermal catalysis of the MnOx/g‐C3N4 composite remains unresolved.In this paper,MnOx/g‐C3N4 catalysts with different molar ratios were synthesized by the precipitation approach at room temperature.The as‐prepared catalysts exhibit excellent synergistic photo‐thermal catalytic performance towards the purification of NO in air.The MnOx/g‐C3N4 catalysts contain MnOx with different valence states on the surface of g‐C3N4.The thermal catalytic reaction for NO oxidation on MnOx and the photo‐thermal catalytic reaction on 1:5 MnOx/g‐C3N4 were investigated by in situ diffuse reflectance infrared Fourier transform spectroscopy(in situ DRIFTS).The results show that light exerted a weak effect on NO oxidation over MnOx,and it exerted a positive synergistic effect on NO conversion over 1:5 MnOx/g‐C3N4.A synergistic photo‐thermal catalytic cycle of NO oxidation on MnOx/g‐C3N4 is proposed.Specifically,photo‐generated electrons(e?)are transferred to MnOx and participate in the synergistic photo‐thermal reduction cycle(Mn4+→Mn3+→Mn2+).The reverse cycle(Mn2+→Mn3+→Mn4+)can regenerate the active oxygen vacancy sites and inject electrons into the g‐C3N4 hole(h+).The active oxygen(O?)was generated in the redox cycles among manganese species(Mn4+/Mn3+/Mn2+)and could oxidize the intermediates(NOH and N2O2?)to final products(NO2?and NO3?).This paper can provide insightful guidance for the development of better catalysts for NOx purification.
