Nitrogen defects (Nd)-engineered single-atom Co-Nx catalyst toward efficient electrochemical water splitting

The rational design of high-performance electrocatalysts is essential for promoting the industrialization of electrocatalytic water-splitting technology. Herein, nitrogen-defects (Nd)-enriched g-C 3 N 4 (CN)-supported cobalt single-atom catalysts (Co-Nd/CN) are fabricated as high-efficiency bifunctional electrocatalysts for water splitting. Abundant Nd improves substrate conductivity and modulates the electronic structure of Co-N x active sites simultaneously. Benefiting from abundant coordination sites, lower charge transfer dynamics, and surface reactions, the optimized Co-Nd/CN exhibits the lowest overpotentials of 172 and 310 mV vs. RHE for HER and OER, respectively, at 10 mA cm −2 . Additionally, Co-Nd/CN delivers a full-cell voltage of 1.53 V at 10 mA cm −2 for overall water splitting with a Faradaic efficiency of 87.5%. Extended durability measurements demonstrate robust catalytic stability for Co-Nd/CN over 100 h of continuous operation. This work puts forward a novel approach based on elemental doping and defect engineering for the design of effective and enduring catalysts for water splitting.