Designing a step-scheme(S-scheme)heterojunction photocatalyst with vacancy engineering is a reliable approach to achieve highly efficient photocatalytic H_(2)production activity.Herein,a hollow ZnO/ZnS S-scheme hetero...Designing a step-scheme(S-scheme)heterojunction photocatalyst with vacancy engineering is a reliable approach to achieve highly efficient photocatalytic H_(2)production activity.Herein,a hollow ZnO/ZnS S-scheme heterojunction with O and Zn vacancies(VO,Zn-ZnO/ZnS)is rationally constructed via ion-exchange and calcination treatments.In such a photocatalytic system,the hollow structure combined with the introduction of dual vacancies endows the adequate light absorption.Moreover,the O and Zn vacancies serve as the trapping sites for photo-induced electrons and holes,respectively,which are beneficial for promoting the photo-induced carrier separation.Meanwhile,the S-scheme charge transfer mechanism can not only improve the separation and transfer efficiencies of photo-induced carrier but also retain the strong redox capacity.As expected,the optimized VO,Zn-ZnO/ZnS heterojunction exhibits a superior photocatalytic H_(2) production rate of 160.91 mmol g^(-1)h^(-1),approximately 643.6 times and 214.5 times with respect to that obtained on pure ZnO and ZnS,respectively.Simultaneously,the experimental results and density functional theory calculations disclose that the photo-induced carrier transfer pathway follows the S-scheme heterojunction mechanism and the introduction of O and Zn vacancies reduces the surface reaction barrier.This work provides an innovative strategy of vacancy engineering in S-scheme heterojunction for solar-to-fuel energy conversion.展开更多
TiO_(2)纳米材料因其存在高的光生电子-空穴对复合速率、电子迁移率低、导电性差以及可逆容量低等问题,使其在光催化和电化学等领域的应用受到限制。MXene(M n+1 X n T x)作为一种新型的二维过渡金属碳化物、氮化物或碳氮化物,具有独特...TiO_(2)纳米材料因其存在高的光生电子-空穴对复合速率、电子迁移率低、导电性差以及可逆容量低等问题,使其在光催化和电化学等领域的应用受到限制。MXene(M n+1 X n T x)作为一种新型的二维过渡金属碳化物、氮化物或碳氮化物,具有独特的二维层状结构、良好的金属导电性和较高的载流子迁移率等特性,将其引入TiO_(2)纳米材料中构建TiO_(2)/MXene纳米复合材料,利用两者的协同作用可进一步提高光电性能。本文从TiO_(2)纳米材料的角度出发,系统综述了零维、一维和二维TiO_(2)与MXene纳米复合材料的可控制备、结构性能及在光催化和电化学领域应用的最新研究进展,并着重介绍了纳米复合材料的构筑机理及MXene对提高TiO_(2)的光催化和电化学性能的增强机制等,分析了目前TiO_(2)/MXene复合材料的制备及其在光催化和电化学领域应用中存在的不足。此外,从优化制备工艺、提升性能和探索相应的性能增强机制等方面对未来TiO_(2)/MXene复合材料的研究方向进行了展望。展开更多
文摘Designing a step-scheme(S-scheme)heterojunction photocatalyst with vacancy engineering is a reliable approach to achieve highly efficient photocatalytic H_(2)production activity.Herein,a hollow ZnO/ZnS S-scheme heterojunction with O and Zn vacancies(VO,Zn-ZnO/ZnS)is rationally constructed via ion-exchange and calcination treatments.In such a photocatalytic system,the hollow structure combined with the introduction of dual vacancies endows the adequate light absorption.Moreover,the O and Zn vacancies serve as the trapping sites for photo-induced electrons and holes,respectively,which are beneficial for promoting the photo-induced carrier separation.Meanwhile,the S-scheme charge transfer mechanism can not only improve the separation and transfer efficiencies of photo-induced carrier but also retain the strong redox capacity.As expected,the optimized VO,Zn-ZnO/ZnS heterojunction exhibits a superior photocatalytic H_(2) production rate of 160.91 mmol g^(-1)h^(-1),approximately 643.6 times and 214.5 times with respect to that obtained on pure ZnO and ZnS,respectively.Simultaneously,the experimental results and density functional theory calculations disclose that the photo-induced carrier transfer pathway follows the S-scheme heterojunction mechanism and the introduction of O and Zn vacancies reduces the surface reaction barrier.This work provides an innovative strategy of vacancy engineering in S-scheme heterojunction for solar-to-fuel energy conversion.
文摘TiO_(2)纳米材料因其存在高的光生电子-空穴对复合速率、电子迁移率低、导电性差以及可逆容量低等问题,使其在光催化和电化学等领域的应用受到限制。MXene(M n+1 X n T x)作为一种新型的二维过渡金属碳化物、氮化物或碳氮化物,具有独特的二维层状结构、良好的金属导电性和较高的载流子迁移率等特性,将其引入TiO_(2)纳米材料中构建TiO_(2)/MXene纳米复合材料,利用两者的协同作用可进一步提高光电性能。本文从TiO_(2)纳米材料的角度出发,系统综述了零维、一维和二维TiO_(2)与MXene纳米复合材料的可控制备、结构性能及在光催化和电化学领域应用的最新研究进展,并着重介绍了纳米复合材料的构筑机理及MXene对提高TiO_(2)的光催化和电化学性能的增强机制等,分析了目前TiO_(2)/MXene复合材料的制备及其在光催化和电化学领域应用中存在的不足。此外,从优化制备工艺、提升性能和探索相应的性能增强机制等方面对未来TiO_(2)/MXene复合材料的研究方向进行了展望。
