摘要: The catalytic performance of single-atom catalysts in CO2 photoreduction can be optimized through precise modulation of the coordination structures of single-atoms. In this study, Ru single-atoms (Ru-SAs) immobilized on the Zr6O8 clusters of a porphyrinic metal–organic framework (Zn-PCN-222) were modified with sulfhydryl groups (–SH). The resulting RuS-SAs@Zn-PCN-222 exhibited high photocatalytic activity for CO2 reduction to HCOO− using ammonia borane as the H* donor, giving rise to a HCOO− production rate of 54.4 mmol·g–1·h–1 with 99.9% selectivity, which was approximately 20.1 and 4.5 times higher than that of Zn-PCN-222 and –SH-free Ru-SAs@Zn-PCN-222, respectively. Photoelectrochemical measurements demonstrated that the incorporated RuS-SAs enhanced the separation and migration of photogenerated charges in RuS-SAs@Zn-PCN-222. Further in situ experiments revealed that the RuS-SAs could accept photogenerated electrons from Zn-PCN-222 as well as electrons from the –SH groups, and then inject to inert CO2 molecules, thereby facilitating CO2 activation and its subsequent coupling with H* to form HCOO−.