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In this paper, we investigated the role of excited-state hydrogen bonding in the photocatalytic carbon dioxide reduction reaction (CO2RR) utilizing Rose Bengal as a catalyst, through a combined experimental and theoretical approach. Experiments validated the successful conversion of CO2 to CO in a homogeneous aqueous solution system under light irradiation, without additional photosensitizers or sacrificial agents. Theoretically, the DFT/TDDFT calculations modeled the catalyst-reactants as a hydrogen-bonded complex (HBC), understanding the energy, hydrogen, and electron transfer mechanisms induced by excited-state hydrogen bonding. Combining the photophysical and photochemical insights revealed the complete catalytic cycle, identifying the water oxidation process as the rate-limiting step in the entire photocatalytic CO2RR process. Experimental and computational results provide molecular-level insights into the structure–activity relationships. This work enhances comprehension of the pivotal role of excited-state hydrogen bonding and holds significant reference value for enhancing the conversion efficiency in the photocatalytic CO2RR. [ABSTRACT FROM AUTHOR]

Understanding the nature of single‐atom catalytic sites and identifying their spectroscopic fingerprints are essential prerequisites for the rational design of target catalysts. Here, we apply correlated in situ X‐ray absorption and infrared spectroscopy to probe the edge‐site‐specific chemistry of Co−N−C electrocatalyst during the oxygen reduction reaction (ORR) operation. The unique edge‐hosted architecture affords single‐atom Co site remarkable structural flexibility with adapted dynamic oxo adsorption and valence state shuttling between Co(2−δ)+ and Co2+, in contrast to the rigid in‐plane embedded Co1−Nx counterpart. Theoretical calculations demonstrate that the synergistic interplay of in situ reconstructed Co1−N2‐oxo with peripheral oxygen groups gives a rise to the near‐optimal adsorption of *OOH intermediate and substantially increases the activation barrier for its dissociation, accounting for a robust acidic ORR activity and 2e− selectivity for H2O2 production. [ABSTRACT FROM AUTHOR]