Multisite synergistic-modulating elementary steps for efficient alkaline hydrogen evolution via NiCu/NiMoOx nanocomposites

Abstract

Oxide/metal pairs have been developed for use as an efficient alkaline hydrogen evolution reaction (HER) electrocatalyst. Further modulation of the elementary steps to determine the potential catalytic performance and understand the underlying mechanism is urgent and challenging. Herein, a NiCu and NiMoO_x nanocomposite (NiCu/MoO_x) with an adjustable surface composition for use in alkaline HERs is reported. The combination of X-ray adsorption near-edge structure (XANES), SCN⁻ poisoning, and density functional theory (DFT) investigation reveals that the excessive OH_ads adsorption can promote water dissociation while leading to hydroxyl poisoning. The introduced high valence Mo can promote the formation of low value Ni^δ+ to optimize OH_ads adsorption. Meanwhile, the adjustable NiCu solid solution can achieve optimal hydrogen adsorption which boosts the H_ads transfer. The obtained NiCu/MoO_x demonstrates an excellent HER performance, characterized by a tiny overpotential of 14 mV at 10 mA cm⁻² and fast alkaline HER kinetics with a small Tafel slope of 38.3 mV dec⁻¹. The results of this research suggest that integrating a multi-component to match OH_ads and H_ads active sites is an effective strategy for promoting alkaline HER.