单原子催化剂在氧还原反应中的分子级调控

Structure Regulation of Single-atom Catalysts in Oxygen Reduction Reactions

氧还原反应(ORR)在电化学能量存储和转换系统以及精细化学制剂的清洁合成中发挥着重要作用.然而,ORR过程的动力学极其缓慢,需要使用铂族贵金属催化剂加快其反应动力学速率.铂基催化剂的高成本严重阻碍了其大规模的商业化.由于单原子催化剂(SACs)具有结构明确、本征活性高和原子效率高的特点,有望取代昂贵的铂族贵金属催化剂.迄今,在进一步提高SACs的ORR活性方面已有大量的研究报道,包括定制金属中心的配位结构、丰富金属中心的浓度以及设计衬底的电子结构和孔隙率等.本文综合评述了近年来SACs在ORR性能以及与ORR相关的H_(2)O_(2)生产、金属-空气电池和低温燃料电池等方面的应用研究进展.总结了通过引入其它金属或配体来调整孤立金属中心的配位结构、通过增加金属负载来增加单原子位点的浓度以及通过优化载体的孔隙度来优化催化性能和电子传输等方面的研究进展,并对SCAs的未来发展方向和面临的挑战提出了展望.

Oxygen reduction reaction(ORR)plays an important role in the clean synthesis of electrochemical energy storage and conversion systems. However,the kinetics of the ORR process is slow and requires platinum group noble metal catalysts to accelerate the reaction. The high cost of platinum-based catalysts has severely hindered their largescale commercialization. Single atom catalysts(SACs)has the specific structure,high intrinsic activity and efficient atomic utilization. It is expected to replace platinum group noble metal catalysts. In order to improve the ORR activity of SACs,many strategies have been developed,including customizing the coordination structure of the metal center,enriching the concentration of the metal center,and designing the electronic structure and porosity of the substrate.In this review,we summarized recent advances of SACs in ORR performance and the application research progress of H_(2)O_(2),metal-air batteries,fuel cells. Relevant progress on adjustment of the coordination structure of isolated metal centers by doping other metals or ligands,increasing the concentration of single-atom sites by increasing metal loading,and optimizing the porosity of the carrier to optimize mass and electron transport. Perspectives on future directions and challenges of SACs are presented.