Interface-engineered atomically thin Ni3S2/MnO2 heterogeneous nanoarrays for efficient overall water splitting in alkaline media

Designing bifunctional non-noble metal electrocatalysts with excellent hydrogen and oxygen evolution performances is a promising candidate for sustainable generation of renewable and clean hydrogen energy. Herein, an atomically thin Ni3S2/MnO2 heterogeneous nanoarray located on Ni foam (NF-Ni3S2/MnO2) is developed for overall water splitting. The construction strategy involves a simple two-step hydrothermal conversion, and the morphology and composition of the hybrid nanoarray can be easily customized. The fabricated NF-Ni3S2/MnO2 with a certain exposed interface and active sites perfectly integrated and optimized the advantages of both several layered Ni3S2 and MnO2, realizing the desired fast kinetics and outstanding performance for overall water splitting in alkaline media. Consequently, the constructed NF-Ni3S2/MnO2 reveals a low overpotential (η10) of 102 mV and 260 mV at a 10 mA cm−2 current density in 1.0 M KOH for HER and OER, respectively. Moreover, it achieves a current density of 10 mA cm−2 at a low voltage of only 1.52 V throughout the overall water splitting, which is outperforming the currently reported Pt/C-IrO2/C couple. Furthermore, density functional theory calculations evidence that the excellent total hydrolysis of NF-Ni3S2/MnO2 is attributed to the hierarchical heterointerfaces, which results in effective adsorption and cleavage of H2O molecule on the catalyst surface.