Multiphasic interfaces boost hydrogen evolution reaction of bifunctional NiFe LDH electrocatalyst via sulfur-phosphorus co-thermal treatment for efficient overall water-splitting

Although low-cost nickel-iron layered double hydroxide (NiFe LDH) has admirable electrolytic activity for oxygen evolution reaction (OER), the high energy barrier of hydrogen adsorption restricts its application as a bifunctional catalyst for alkaline overall water-splitting. Herein, sulfur (S) and phosphorus (P) elements have been co-introduced into a NiFe LDH on a nickel-iron foam (NIF) via sulfurating and phosphorizing co-thermal treatment, whereupon the phase composition and electronic structure are optimized, forming the (S, P)-NiFe LDH/NIF bifunctional catalyst. Benefiting from the synergy effect caused by the multiphasic interfaces, the (S, P)-NiFe LDH/NIF surprisingly exhibits an ultra-low overpotential of only 29 mV to induce hydrogen evolution reaction (HER) at a current density of 10 mA cm −2 , showing outstanding HER performance. In addition, the obtained catalyst also shows remarkable OER performance with an overpotential of only 190 mV at a current density of 10 mA cm −2 . Moreover, the symmetric electrolyzer assembled by the bifunctional (S, P)-NiFe LDH/NIF catalysts can deliver a current density of 100 mA cm −2 at a cell voltage of only 1.75 V, and maintain the reaction activity continuously for up to 200 h, showing excellent overall water-splitting performance. This work is expected to provide a new insight for designing and synthesizing bifunctional electrocatalysts based on low-cost NiFe LDH, further promoting and realizing the large-scale water-electrolysis.