Fabrication of NiCo@Ni3S2/Nickel foam electrocatalyst with ultrathin NiCo layered double hydroxide film wrapping Ni3S2 nanoarrays for efficient oxygen evolution reaction

Developing efficient and durable electrocatalysts for faster anodic oxygen evolution reaction (OER) in water electrolysis is significant to hydrogen production. In this study, an electrocatalyst NiCo@Ni3S2/NF for OER was prepared using a two-step method. Ni3S2 nanoarray was initially grown on a nickel foam (NF) substrate, followed by the deposition of an ultrathin NiCo layered double hydroxides (LDH) film that wrapped around the surface of Ni3S2/NF to form a hill-shaped morphology. Characterization results of SEM, TEM, and XPS confirmed the presence of a heterogeneous interface with an enlarged contact area between NiCo LDH and Ni3S2 in this unique structure. This leads to more active species such as Ni3+ and Co3+, resulting in enhanced intrinsic catalytic activity. This hill-shaped topography also demonstrated to be conducive to the release of oxygen bubbles generated during OER process. The prepared electrocatalyst NiCo@Ni3S2/NF exhibits a rapid charge transfer rate and a Tafel slope as low as 63 mV·dec−1. It therefore demonstrates excellent OER performance with a low overpotential of 245 mV at current density of 10 mA cm−2, and long-term stability under both currents of 10 and 50 mA cm−2.