High electronegativity of Ag and P in high-entropy materials synergistically promotes efficient water electrolysis

A high-entropy phosphide catalyst (HEMP-300) comprising Ni, Fe, Cr, Co, Ag, and P was synthesized through a one-step hydrothermal reaction followed by in-situ phosphorization. The incorporation of highly electronegative elements Ag and P effectively adjusted the catalyst's electronic structure, enhancing electron transfer significantly. Additionally, Cr dissolution during water electrolysis increased the number of active sites and optimized the electronic structure on the electrode surface. The synthesized HEMP-300 displayed excellent oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) activity and stability in 1.0 M KOH solution, especially at high current densities, achieving notably low overpotentials (OER: 253 mV @ 100 mA cm-2; HER: 216 mV @ 50 mA cm-2) and small Tafel slopes (OER: 40.7 mV dec-1; HER: 60 mV dec-1). Moreover, a twoelectrode electrolyzer using HEMP-300 as both the anode and cathode exhibited a low cell voltage of 1.712 V at a current density of 50 mA cm-2, outperforming many previously reported electrocatalysts. As a result, the developed HEMP-300 demonstrates considerable promise for large-scale commercial applications in green hydrogen production.