S and Se-enhanced intrinsic activity of Co(OH)2 for overall water splitting

Designing catalysts that simultaneously optimize both hydrogen and oxygen evolution reaction (HER and OER) emerges as a critical materials challenge. Co(OH)₂ is recognized as an effective OER electrocatalyst, but the low HER activity limits its application in overall water splitting. In this work, we synthesized sulfur (S) and selenium (Se) doped Co(OH) 2 catalysts with significantly enhanced HER activity using an electrochemical deposition method. The S-Co(OH) 2 and Se-Co(OH) 2 catalysts own low HER overpotentials of 48 mV and 59 mV at 10 mA cm −2 . And they require 1.56 V and 1.64 V at the same current density for water splitting, the sustain stable performance for > 100 h at current densities (100 mA cm −2 ) show their practical durability. Density Functional Theory (DFT) calculations and experimental results reveal that non-metal doping induces electronic reconfiguration of Co and optimizes the ΔG H* value for intermediate formation, thus accelerating hydrogen generation and enhancing the intrinsic HER activity. This work presents an effective strategy for incorporating non-metal elements into transition metal-based catalysts, and provides insight to boost HER intrinsic activity and achieve bifunctional catalytic performance for water splitting.