Mg-doped SrTaO_(2)N as a visible-light-driven H_(2)-evolution photocatalyst for accelerated Z-scheme overall water splitting  

可见光驱动的Mg掺杂SrTaO_(2)N催化剂助力Z-型光催化全水分解

作　　者：Jun Xu Ying Luo Qiaoqi Guo Wenzheng Sun Shanshan Chen Zheng Wang Hong He 徐君;罗英;郭乔琪;孙文峥;陈闪山;王征;贺泓(中国科学院生态环境研究中心,大气环境与污染控制实验室,北京100085;河南理工大学化学与化工学院,河南焦作454000;南开大学材料科学与工程学院,国家新材料研究院,天津300350;中国科学院大学资源与环境学院,北京101408)

机构地区：[1]Laboratory of Atmospheric Environment and Pollution Control,Research Center for Eco-Environmental Sciences,Chinese Academy of Sciences,Beijing 100085,China [2]College of Chemistry and Chemical Engineering,Henan Polytechnic University,Jiaozuo 454000,Henan,China [3]School of Materials Science and Engineering&National Institute for Advanced Materials,Nankai University,Tianjin 300350,China [4]College of Resource and Environment,University of Chinese Academy of Sciences,Beijing 101408,China

出　　处：《Chinese Journal of Catalysis》2024年第10期70-78,共9页催化学报（英文）

基　　金：国家自然科学基金(22376207,22272082);中国博士后科学基金面上项目(2022M723315);中国科学院生态环境研究中心CCUS战略重点项目。

摘　　要：Perovskite SrTaO_(2)N is one of the most promising narrow-bandgap photocatalysts for Z-scheme overall water splitting.However,the formation of defect states during thermal nitridation severely hinders the separation of charges,resulting in poor photocatalytic activity.In the present study,we successfully synthesize SrTaO_(2)N photocatalyst with low density of defect states,uniform morphology and particle size by flux-assisted one-pot nitridation combined with Mg doping.Some important parameters,such as the size of unit cell,the content of nitrogen,and microstructure,prove the successful doping of Mg.The defect-related carrier recombination has been significantly reduced by Mg doping,which effectively promotes the charge separation.Moreover,Mg doping induces a change of the band edge,which makes proton reduction have a stronger driving force.After modifying with the core/shell-structured Pt/Cr_(2)O_(3)cocatalyst,the H_(2)evolution activity of the optimized SrTaO_(2)N:Mg is 10 times that of the undoped SrTaO_(2)N,with an impressive apparent quantum yield of 1.51%at 420 nm.By coupling with Au-FeCoO_(x)modified BiVO_(4)as an O_(2)-evolution photocatalyst and[Fe(CN)_(6)]_(3)−/[Fe(CN)_(6)]_(4)−as the redox couple,a redox-based Z-scheme overall water splitting system is successfully constructed with an apparent quantum yield of 1.36%at 420 nm.This work provides an alternative way to prepare oxynitride semiconductors with reduced defects to promote the conversion of solar energy.光催化分解水技术可以通过太阳能驱动的光解水过程将太阳能大规模转化为清洁可再生的氢能,是解决能源危机和环境污染问题的理想途径.与一步光激发全水分解不同,两步光激发全解水(乙-型全解水)放宽了严格的带隙要求,是一种非常有前景的策略。然而,两步激发光催化分解水效率仍远低于理论值.开发可见光响应的光催化剂有望提升太阳能的利用率.SrTaO_(2)N因能够吸收600nm可见光,且具有合适的导带和价带优点,引起科研工作者的广泛关注.然而,高温氮化过程中产生的大量缺陷态成为光生电荷复合中心,抑制了光生电子和空穴的分离与传输.因此,采取有效的措施控制SrTaO_(2)N的缺陷密度对提高光催化性能至关重要,但具有很大的挑战性.本文采用Mg掺杂策略,利用KC1熔融盐辅助的热氮化法合成了缺陷密度低、颗粒尺寸和形貌均一的Mg掺杂SrTaO_(2)N(SrTaO_(2)N:Mg)光催化剂.通过X射线粉末衍射(XRD)、XRD数据的Rietveld精修、微观形貌分析(扫描电子显微镜和透射电子显微镜)和元素分析等证明了Mg占据了SrTaO_(2)N钙钛矿型晶格的Ta位点,紫外-可见漫反射光谱(UV-visDRS)和X射线光电子能谱表明,Mg的掺杂在一定程度上抑制了高温氮化过程中低价Ta缺陷物种(光生载流子复合中心)的产生.结合UV-visDRS谱和莫特-肖特基曲线结果,证明了Mg掺杂所引起的能带结构变化为水分解产氢反应提供了更强的驱动力,有利于光生载流子的进一步分离采用低温稳态光致发光光谱、时间分辨光致发光衰减光谱、光电流强度曲线和电化学阻抗曲线等分析了Mg掺杂前后SrTaO_(2)N光催化剂光生载流子的分离和传输行为.研究结果表明,Mg掺杂有效地抑制了缺陷态的产生,促进了光生载流子的分离与传输.通过浸渍氢化和光沉过程分步修饰了Pt和Cr_(2)O_(3),实现了SrTaO_(2)N:Mg表面核壳型Pt/CrO_(3)析氢助催化剂的成功�

关 键 词：Photocatalytic overall water splitting SrTaO_(2)N photocatalyst Mg doping Defect density COCATALYST 

分 类 号：X703[环境科学与工程—环境工程]