摘要
二氧化钛是目前被广泛研究和运用的金属氧化物。该文章总结当前二氧化钛负载单原子金属,包括铂、钯、铱、铑、铜、钌等催化剂的制备方法、表征手段和光催化反应的运用。二氧化钛表面负载单原子金属的主要制备方法包括表面缺陷法、表面修饰、高温脉冲及表面金属配体组装等。该文章探讨这些制备方法的控制条件和实用范围,并讨论负载型单原子催化剂的表征手段,包括电镜表征(球差校正扫描透射显微镜和扫描隧道显微镜)和谱学分析(扩展的X-光吸收精细结构分析、分子探针红外吸收谱等)。最后文章针对二氧化钛负载单原子催化剂在光催化水裂解产氢的作用机理和在光催化二氧化碳还原反应的运用做出讨论。
Titania(TiO_(2))has been among the most widely investigated and used metal oxides over the past years,as it has various functional applications.Extensive research into TiO_(2) and industrial interest in this material have been triggered by its high abundance,excellent corrosion resistance,and low cost.To improve the activity of TiO_(2) in heterogeneous catalytic reactions,noble metals are used to accelerate the reactions.However,in the case of nanoparticles supported on TiO_(2),the active sites are usually limited to the peripheral sites of the noble metal particles or at the interface between the particle and the support.Thus,highly dispersed single metal atoms are desired for the effective utilization of precious noble metals.The study of oxide-supported isolated atoms,the so-called single-atom catalysts(SACs),was pioneered by Zhang’s group.The high dispersion of precious noble metals results helps reduce the cost associated with catalyst preparation.Because of the presence of active centers as single atoms,the deactivation of metal atoms during the reaction,e.g.,by coking for large agglomerates,is retarded.The unique coordination environment of the noble metal center provides special sites for the reaction,consequently increasing the selectivity of the reaction,including the enantioselectivity and stereoselectivity.Hence,supported SACs can bridge homogenous and heterogeneous reactions in solution as they provide selective reaction sites and are recyclable.Moreover,owing to the high site homogeneity of the isolated metal atoms,SACs are ideal models for establishing the structure-activity relationships.The present review provides an overview of recent works on the synthesis,characterization,and photocatalytic applications of SACs(Pt1,Pd1,Ir1,Rh1,Cu1,Ru1)supported on TiO_(2).The preparation of single atoms on TiO_(2) includes the creation of surface defective sites,surface modification,stabilization by high-temperature shockwave treatment,and metal-ligand self-assembly.Conventional characterization methods are categorized as microscopic imaging and spectroscopic methods,such as aberration-corrected scanning transmission electron microscopy(STEM),scanning tunneling microscopy(STM),extended X-ray absorption fine structure analysis(EXAFS),and diffuse reflectance infrared Fourier transform spectroscopy(DRIFTS).We attempted to address the critical factors that lead to the stabilization of single-metal atoms on TiO_(2),and elucidate the mechanism underlying the photocatalytic hydrogen evolution and CO_(2) reduction.Although many fascinating applications of TiO_(2)-supported SACs in photocatalysis could only be addressed superficially and in a referencing manner,we hope to provide interested readers with guidelines based on the wide literature,and more specifically,to provide a comprehensive overview of TiO_(2)-supported SACs.
作者
周雪梅
Xuemei Zhou(School of Chemical Engineering,Sichuan University,Chengdu 610065,China)
出处
《物理化学学报》
SCIE
CAS
CSCD
北大核心
2021年第6期5-17,共13页
Acta Physico-Chimica Sinica
基金
四川大学2020年双百人才工程B计划项目资助。
关键词
二氧化钛
单原子催化剂
表面稳定性
单原子表征
光催化产氢
Titanium dioxide
Single atom catalyst
Stabilization
Characterization
Photocatalytic H_(2)evolution
