Promoting the activity of Ni3S2-x/Ni2P fuzzy-like nanorods as a bifunctional electrocatalyst for efficient overall water splitting through dealloying and active site design strategy

Abstract

High-efficiency bifunctional electrocatalysts can reduce the hydrogen and oxygen evolution reaction (HER/OER) overpotential, which is of great significance for hydrogen production by water splitting. However, issues remain with large-scale preparation and a bottleneck for design separation. In this work, we reported on a facile method using a nanostructured transition metal sulfide (TMS) Ni3S2-Vs-Ps nanorod (NSVP NR) bifunctional catalyst material, which was prepared by dealloying and doping to obtain novel fuzzy-like NRs with heterostructures in triphasic points. The experimental results and first-principles calculations both revealed that the P-dopants changed the coordination environment between the inner S-vacancy Ni3S2-x NRs and outer Ni2P nanoparticles in the heterojunctions of the triphasic points, which as active sites could accelerate the movement of electron charges in the metal catalyst. The NVSP NRs showed excellent adsorption energy results, which on the Ni site were ΔGH* at 0.12 eV for HER and ΔGmax at 0.48 eV for OER. The optimized NSVP NRs demonstrated a current density of 100 mA/cm2 at the lowest overpotential of only 148 mV for HER and 311 mV for OER. Moreover, a cell voltage of 1.565 V could achieve 10 mA/cm2 when assembled in 1 M KOH solution for overall water splitting (OWS). Therefore, these findings provide a novel route from traditional dealloying corrosion for creating nanostructures and for producing new energy, offering insight into bifunctional catalyst design and application.