摘要：Single-atom catalysts(SACs)have been widely used in heterogeneous catalysis owing to the maximum utilization of metal-active sites with controlled structures and well-defined *** tailored coordination with nitrogen atom,the metal-nitrogen(M-N)-based SACs have demonstrated interesting physical,optical and electronic properties and have become intense in photocatalysis and electrocatalysis in the past *** substantial efforts in constructing various M–N-based SACs,the principles for modulating the intrinsic photocatalytic and electrocatalytic performance of their active sites and catalytic mechanism have not been sufficiently ***,the present review intends to shed some light on recent research made in studying the correlation between intrinsic electronic structure,catalytic mechanism,single-metal atom(SMA)confinement and their photocatalytic and electrocatalytic activities(conversion,selectivity,stability and etc).Based on the analysis of fundamentals of M–N-based SACs,theoretical calculations and experimental investigations,including synthetic methods and characterization techniques,are both included to provide an integral understanding of the underlying mechanisms behind improved coordination structure and observed ***,the challenges and perspectives for constructing highly active M–N based photocatalysis and electrocatalysis SACs are *** particular,extensive technical and mechanism aspects are thoroughly discussed,summarized and analyzed for promoting further advancement of M-N-based SACs in photocatalysis and electrocatalysis.

摘要：利用取之不尽的太阳能资源进行光催化水裂解制氢是缓解全球能源危机、实现碳中和战略的一项有前景的技术。石墨相氮化碳(g-C_(3)N_(4))因成本低且稳定性高在光催化产氢领域备受关注。然而,纯g-C_(3)N_(4)存在表面积小、电子转移慢、光生载流子复合快等缺陷,产氢性能通常不佳。本研究通过直接热解硫酸铵和三聚氰胺混合物,成功实现硫物种对g-C_(3)N_(4)氮位点的原位取代,开发出一种高效的硫掺杂g-C_(3)N_(4) (S-g-CN)光催化剂。系列结构和光谱表征证实硫的成功掺杂。密度泛函理论的第一性原理计算表明S活性位对氢的吸附吉布斯自由能近乎为零(~0.26 eV),揭示S掺杂在优化H活性中间体吸附和解吸过程中起着重要作用。透射电子显微镜和原子力显微镜测试结果表明,S-g-CN具有超薄的纳米片状结构,其片层厚度约为2.5 nm。随后的氮气吸脱附等温线和光电化学性质测试结果表明,S掺杂不仅可显著增大g-C_(3)N_(4)比表面积,而且还能有效提高其光生电子-空穴对的转移、分离和氧化还原能力。得益于材料良好的结构特性,S-g-CN的光催化产氢速率高达4923 μmol·g^(-1)·h^(-1),是原始g-C_(3)N_(4)的28倍,超越诸多最近报道的其它S掺杂g-C_(3)N_(4)光催化剂。而且,S-g-CN的表观量子效率高达3.64%。本研究除了开发一种高效的光催化剂,还将为高性能g-C_(3)N_(4)基催化剂的设计提供有益借鉴。