Synthesis of NiSe2@M (M=Cu, Fe and Zn)–NiCo LDH with porous structure on nickel foam for overall fresh and seawater splitting

We report the preparation of NiSe2@M (M = Cu, Fe, and Zn)–NiCo LDH catalysts with a porous structure composed of nanospheres loaded with nanosheets on a nickel foam substrate using a hydrothermal method. The designed NiSe2@Fe–NiCo LDH catalysts exhibit excellent performance in both the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) in alkaline freshwater and seawater electrolytes. For OER, a current density of 10 mA cm−2 is achieved with only a 260 mV overpotential, while for HER, 10 mA cm−2 is attained with only a 130 mV overpotential. These catalysts maintain good stability in alkaline freshwater and seawater environments. Density functional theory (DFT) analyses indicate that the Fe–NiCo LDH electrode has the optimal Gibbs free energy, underscoring its catalytic role. The introduction of NiSe2 enhances the electrical conductivity of the NiSe2@Fe–NiCo LDH electrode. The synergistic catalysis of NiSe2 and Fe–NiCo LDH contributes to the superior catalytic performance of the electrode. This work offers a novel approach to explore efficient and stable non-precious metal-doped catalysts for freshwater and seawater splitting.