Unraveling the Essential Role of Consecutive Protonation Steps in Photocatalytic CO ₂ Reduction when Using Au Nanorods in a MOF

Abstract The proton‐coupled electron transfer process (PCET) plays a crucial role in both natural and artificial photosynthesis, including CO 2 fixation chemistry. However, difficulties in capturing the transient intermediates generated during the protonation process impede the clarification of the fundamental mechanism behind photocatalytic CO 2 reduction. Herein, we report a general killing two birds with one stone strategy by spatially confining Au nanorods within a typical porphyrin metal–organic framework (MOF). Interestingly, 2.4‐fold increase in CH 4 /CO selectivity and 12‐fold increase in CH 4 production were observed after loading of Au nanorods, indicative of a strengthened protonation process in the photocatalytic CO 2 reduction. More importantly, the plasmonic effect from Au nanorods simultaneously boosted the in situ Raman signals of…