Proton Capture Strategy for Enhancing Electrochemical CO2 Reduction on Atomically Dispersed Metal-Nitrogen Active Sites**

Electrocatalysts play a key role in accelerating the sluggish electrochemical CO2 reduction (ECR) involving multi-electron and proton transfer. We now develop a proton capture strategy by accelerating the water dissociation reaction catalyzed by transition-metal nanoparticles (NPs) adjacent to atomically dispersed and nitrogen-coordinated single nickel (Ni-N-x) active sites to accelerate proton transfer to the latter for boosting the intermediate protonation step, and thus the whole ECR process. Aberration-corrected scanning transmission electron microscopy, X-ray absorption spectroscopy, and calculations reveal that the Ni NPs accelerate the adsorbed H (H-ad) generation and transfer to the adjacent Ni-N-x sites for boosting the intermediate protonation and the overall ECR processes. This proton capture strategy is universal to design and prepare for various high-performance catalysts for diverse electrochemical reactions even beyond ECR.