利用电荷分离调控S型异质结光催化氧化产物选择性  

Unveiling product selectivity in S-scheme heterojunctions:Harnessing charge separation for tailored photocatalytic oxidation

作　　者：谷苗莉 杨祎 程蓓[1] 张留洋 肖鹏 陈涛[3] Miaoli Gu;Yi Yang;Bei Cheng;Liuyang Zhang;Peng Xiao;Tao Chen(State Key Laboratory of Advanced Technology for Materials Synthesis and Processing,Wuhan University of Technology,Wuhan 430070,Hubei,China;Laboratory of Solar Fuel,Faculty of Materials Science and Chemistry,China University of Geosciences,Wuhan 430078,Hubei,China;Hefei National Laboratory for Physical Sciences at Microscale,CAS Key Laboratory of Materials for Energy Conversion,Department of Materials Science and Engineering,University of Science and Technology of Chin1,Hefei 230026,Anhui,China)

机构地区：[1]武汉理工大学材料复合新技术国家重点实验室,湖北武汉430070 [2]中国地质大学(武汉)材料与化学学院太阳燃料实验室,湖北武汉430078 [3]中国科学技术大学材料科学与工程系,中国科学院能量转换材料重点实验室,合肥微尺度物质科学国家实验室,安徽合肥230026

出　　处：《Chinese Journal of Catalysis》2024年第4期185-194,共10页催化学报（英文）

基　　金：国家重点研发计划(2022YFB3803600);国家重点研发计划(2022YFE0115900);国家自然科学基金(52322214);国家自然科学基金(22278383);国家自然科学基金(22238009);国家自然科学基金(22278324);国家自然科学基金(52073223);湖北省自然科学基金(2022CFA001);湖北省自然科学基金(2023AFA088);湖北省重点科技发展计划项目(2023BAB113)。

摘　　要：半导体光催化技术为太阳能的高效利用提供了巨大的潜力.尽管众多单一半导体材料,如TiO_(2),CdS,g-C_(3)N_(4)等,已被广泛制备并用于光催化反应,但在单一光催化剂中,光生电子和空穴常因强库仑引力作用而迅速复合,导致光催化效率较低,难以实现大规模产业化应用.针对这一问题,开发S型异质结光催化剂成为提高催化效率的有效途径之一.该异质结不仅能实现氧化还原位点在空间上的有效分离,同时保持了较强的氧化还原能力.然而,目前关于空间分离对光催化氧化产物选择性的影响研究较少.因此,深入探究S型异质结光催化剂中空间分离对产物选择性的作用机制,对于优化光催化过程、提高产物选择性具有重要意义.本文构建了具有良好暴露活性位点的2D/2D层状BiOBr/ZnIn_(2)S_(4)S型异质结(BOB/ZIS).实验发现,在纯ZnIn_(2)S_(4)体系中,由于无法实现空间上的有效电荷分离,氧还原反应(ORR)生成的H_(2)O_(2)在光生空穴的作用下进一步转化为•OH(羟基自由基),其氧化能力超过了体系中的光生空穴,导致2,5-呋喃二甲醛被过度氧化为经济性不高的产物呋喃二甲酸.在BOB/ZIS异质结中,我们实现了光生电子-空穴的有效转移和丰富的活性中心利用.ZnIn_(2)S_(4)价带上的电子通过ORR持续生成H_(2)O_(2)(1.15 mmol∙L^(-1),5 h),而BiOBr导带上的空穴则将5-羟甲基糠醛(HMF)氧化为具有高经济价值的2,5-呋喃二甲醛(有机合成中有价值的中间体).这一结果证实了S型异质结中光生电子-空穴的有效空间分离能够同时促进H_(2)O_(2)的产生和HMF的选择性氧化为2,5-呋喃二甲醛.这一发现不仅揭示了S型异质结在光催化反应中的优势,还证实了其相对于传统牺牲剂的经济可行性.原位光照X射线光电子能谱、飞秒超快瞬态吸收光谱和密度泛函理论计算均证实,在BOB/ZIS界面之间构建了S型电荷转移机制,加速了光生电子-空穴对�The utilization of semiconductor-based photocatalytic technology holds immense promise for harnessing solar energy.However,the inherent issue of strong Coulombic attraction between photo-generated electrons and holes within a single photocatalyst often leads to rapid recombination,limiting efficiency.Addressing this challenge,the development of S-scheme heterojunction photocatalysts has emerged as an effective strategy.Nevertheless,the impact of this spatial separation on the photocatalytic reaction has remained largely unexplored.This study reveals that the recombination of useless charge carriers significantly influences the oxidation product.In the pristine ZnIn_(2)S_(4) system,the spatially unseparated holes interact with the H_(2)O_(2) generated on the surface of ZnIn_(2)S_(4),all of which are converted to•OH with higher oxidation ability,causing excessive oxidation of 5-hydroxymethylfurfural(HMF).Conversely,the BiOBr/ZnIn_(2)S_(4) system,effective separation of electrons and holes in space,selectively oxidizes HMF into valuable 2,5-dimethylfuran(DFF)while efficiently generating H_(2)O_(2)(1.15 mmol∙L^(-1),5 h).This outcome,elucidated through in-situ Fourier-transform infrared spectroscopy,density functional theory calculation,and femtosecond transient absorption spectroscopy,underscores the role of spatially separated charge carriers in influencing product selectivity within S-scheme heterojunctions.This work sheds new light on selective oxidation phenomena and underscores the significance of charge separation in S-scheme heterojunctions.

关 键 词：BiOBr/ZnIn_(2)S_(4) S型异质结 过氧化氢制备 5-羟甲基糠醛选择性转化 转化机理 

分 类 号：O643.36[理学—物理化学] O644.1[理学—化学]