Self-supported Ni5P4/Co3O4 electrode with optimized electron structure as an efficient electrocatalyst for alkaline hydrogen evolution reaction

Abstract

Developing highly effective and robust catalysts for alkaline hydrogen evolution reaction using non-precious metals is essential. However, most transition metal catalysts encounter significant challenges as they typically operate under large overpotentials due to the sluggish kinetics in alkaline solutions. In this work, ultra-thin Ni₅P₄ nanosheets are in-situ integrated on Co₃O₄ nanowires to construct a heterogeneous tandem Ni₅P₄/Co₃O₄ electrode, which is used as a high-performance catalyst for hydrogen evolution reaction in alkaline media. The integrated Ni₅P₄/Co₃O₄/NF heterostructure electrode demonstrates exceptional catalytic performance for the hydrogen evolution reaction. This is due to its unique hierarchical structure, which facilitates electron transfer and mass transport. Additionally, the downward shift of the Co-3d orbital at the Ni₅P₄/Co₃O₄ interface enhances the reactivity and lowers the energy barrier of the water dissociation step. The initial potential is close to 0 V and only take overpotentials as low as ≈ 190 and ≈ 230 mV to reach current densities of 500 and 1000 mA cm⁻² in 1 M KOH, respectively; which are ≈ 13.5-fold and ≈ 11.9-fold higher than conventional Ni₂P/NF catalyst. The excellent electrocatalytic performance of the Ni₅P₄/Co₃O₄/NF heterostructure electrode demonstrates its significant potential to replace precious Pt-based catalysts for large-scale electrochemical hydrogen production.