Electronic structure engineering of cobaltous sulfide for high-efficient pH-universal hydrogen evolution/alkaline oxygen production

Engineering-efficient, stable and low-cost electrocatalyst is facing with essential demand for overall water cracking to generate hydrogen and oxygen. Higher activation energy and sluggish kinetics are the main limiting factors for improved yield. In this paper, ZIF-67 was applied to prepare porous metal sulfide and foreign Fe atoms were introduced to substitute Co atoms in situ in CoS to modulate the electronic structure of the active centers. The as-constructed catalytic system reveals expected pH-universal HER performance and alkaline OER activity, and requires quite small over-potentials. Our theoretical prediction verifies the effective charge transfer between the doped Fe atom and its neighboring S atoms on the surface and the chemical environment variation in the doping sites. In addition, the improved conductivity and the decreased activation energy barriers are calculated in the FeCoS catalyst, further explaining its superiority in catalyzing OER and HER processes. This strategy is expected to be expandable to multiple energy transformation applications and provide a constructive strategy for fast charge transfer in water splitting. • Non-precious bifunctional electrocatalyst were facile established. • FeCoS/NF-2 exhibited excellent performance for HER in the full pH range. • The chemical environment variation in the doping sites was explored. • DFT calculation explained the reasons for the excellent properties.