Tuning the coupling interface of ultrathin Ni3S2@NiV-LDH heterogeneous nanosheet electrocatalysts for improved overall water splitting

Tuning the coupling interface of a heterostructured catalyst is an effective approach to achieve abundant surface catalytic active sites and strong electronic interactions among active materials for improving electrocatalytic water splitting performance. Herein, we report a novel heterogeneous catalyst comprising Ni3S2 nanoparticles embedded in ultrathin NiV-layered double hydroxide nanosheet arrays supported on nickel foam, denoted as Ni3S2@NiV-LDH/NF. We demonstrate that the active edge-state length and the surface chemical state of such NiV-LDH-based heterostructures are well modulated by tailoring the coupling interfaces, resulting in the exposure of more catalytic reaction sites and enhancement of the electronic interactions between NiV-LDH and Ni3S2, thus greatly promoting the water dissociation kinetics. As expected, the optimized Ni3S2@NiV-LDH/NF heterostructures exhibit outstanding electrocatalytic activity for the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), with an extremely low overpotential of 126 mV and 190 mV to deliver 10 mA cm-2 for the HER and OER without iR compensation in alkaline media, respectively. More importantly, Ni3S2@NiV-LDH/NF simultaneously functioned as both the anode and cathode for water splitting to yield a current density of 10 mA cm-2 at a cell voltage of only 1.53 V with an outstanding durability for 160 h. This work provides a new insight into the regulation of the coupling interface for obtaining highly active heterostructured catalysts for overall water splitting.