Unveiling the Proton–Electron Transfer Pathway in Zn-Embedded N-Doped Carbon Catalyst for Enhanced CO₂ Electroreduction

Proton-electron transfer (PET) processes play a pivotal role in numerous electrochemical reactions; yet, effectively harnessing them remains a formidable challenge. Consequently, unveiling the PET pathway is imperative to elucidate the factors influencing the efficiency and selectivity of small molecule electrochemical conversion. In this study, a Zn-NC model catalyst with N and C vacancies was synthesized using a hydriding method to investigate the universal impact of PET on CO₂ electroreduction. The introduction of N vacancies induced the formation of a distinctive Zn-N₃ topological structure and atomically populated Zn^δ+ sites with lower valence states, thereby facilitating the cleavage of the C═O bonds. Conversely, C vacancies led to the formation of stable C-H bonds and tuned the rate of dissociation of H₂O to H*. In comparison to sequential proton-electron transfer, concerted proton-electron transfer significantly enhanced the formation of *COOH species, a critical step in the CO₂ reduction process on a Zn-enhanced N-doped carbon catalyst. The catalyst exhibited a remarkable 96% CO Faradaic efficiency at -0.36 V vs RHE. This research contributes to the ongoing endeavors to unlock the full potential of concerted proton-electron transfer in electrochemical synthesis and its application in sustainable energy and environmental solutions.