摘要
Nature-inspired artificial Z-scheme photocatalyst offers great promise in solar overall water splitting,but its rational design,construction and interfacial charge transfer mechanism remain ambiguous.Here,we design an approach of engineering interfacial band bending via work function regulation,which realizes directional charge transfer at interface and affords direct Z-scheme pathway.Taking BiVO_(4)as prototype,its oxygen vacancy concentration is reduced by slowing down the crystallization rate,thereby changing the work function from smaller to larger than that of polymeric carbon nitride(PCN).Consequently,the photoinduced charge transfer pathway of BiVO_(4)/PCN is switched from type-Ⅱto Z-scheme as evidenced by synchronous illuminated X-ray photoelectron spectroscopy(XPS)and femtosecond transient absorption spectroscopy.Specifically,the direct Z-scheme BiVO_(4)/PCN shows superior photocatalytic performance in water splitting.This work provides deep insights and guidelines to constructing heterojunction photocatalysts for solar utilization.
直接Z型异质结是理想的全解水光催化剂形式之一.C_(3)N_(4)的价带电位约为+1.6 V(vs.NHE,pH 0),在热力学上限制了其产氧性能.C_(3)N_(4)与具有较强氧化电势的半导体复合构建Z型异质结,有利于提高光催化效率.构建直接Z型的关键在于对界面电荷传输路径的精确控制.通过调控半导体的氧缺陷浓度可有效改变其功函数,进而改变异质结界面处的能带弯曲方向以选择性控制光生载流子的传递路径.利用水热法合成BiVO4并降低氧缺陷含量,从而使其功函数逐渐增大.当氧缺陷含量较高时,BiVO_(4)的功函数小于C_(3)N_(4);而当氧缺陷含量较低时,其功函数大于C_(3)N_(4).这种功函数相对值的变化进一步改变了异质结界面处的能带弯曲方向,进而使BiVO_(4)/C_(3)N_(4)由Ⅱ型转变为Z型.与Ⅱ型异质结不同,直接Z型BiVO_(4)/C_(3)N_(4)实现了高效的光催化全解水,且420 nm处的表观量子效率为4.4%.
作者
Shangcong Sun
Ruijie Gao
Xianlong Liu
Lun Pan
Chengxiang Shi
Zheng Jiang
Xiangwen Zhang
Ji-Jun Zou
孙尚聪;高睿杰;刘显龙;潘伦;史成香;姜政;张香文;邹吉军(Key Laboratory for Green Chemical Technology of the Ministry of Education,School of Chemical Engineering and Technology,Tianjin University,Tianjin 300072,China;Collaborative Innovative Center of Chemical Science and Engineering(Tianjin),Tianjin 300072,China;Shanghai Synchrotron Radiation Facility,Shanghai Institute of Applied Physics,Chinese Academy of Sciences,Shanghai 201204,China;d Shanghai Synchrotron Radiation Facility,Zhangjiang Lab,Shanghai Advanced Research Institute,Chinese Academy of Sciences,Shanghai 201210,China)
基金
supported by the National Natural Science Foundation of China(22161142002 and 21978200)。
