3D Nitrogen-Anion-Decorated Nickel Sulfides for Highly Efficient Overall Water Splitting.

Developing non-noble-metal electrocatalysts with high activity and low cost for both the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) is of paramount importance for improving the generation of H fuel by electrocatalytic water-splitting. This study puts forward a new N-anion-decorated Ni S material synthesized by a simple one-step calcination route, acting as a superior bifunctional electrocatalyst for the OER/HER for the first time. The introduction of N anions significantly modifies the morphology and electronic structure of Ni S , bringing high surface active sites exposure, enhanced electrical conductivity, optimal HER Gibbs free-energy (ΔG ), and water adsorption energy change (ΔG ). Remarkably, the obtained N-Ni S /NF 3D electrode exhibits extremely low overpotentials of 330 and 110 mV to reach a current density of 100 and 10 mA cm for the OER and HER in 1.0 m KOH, respectively. Moreover, an overall water-splitting device comprising this electrode delivers a current density of 10 mA cm at a very low cell voltage of 1.48 V. Our finding introduces a new way to design advanced bifunctional catalysts for water splitting.