Optimizing electronic structure of porous Ni/MoO2 heterostructure to boost alkaline hydrogen evolution reaction

Heterostructure engineering is an efficient strategy to synergisticallyimprove electrocatalytic activity. In this work, Ni/MoO2 heterojunction nanorods with porous structure self-supported on nickel foam (NF) are elaborately designed through a facile solution-evaporationmethod followed by a thermal reduction process. Prominently, the optimal electrocatalyst Ni/MoO2@NF-E delivers an exceptionally low overpotential of 19 mV at the current density of 10 mA cm-2 and a small Tafel slope of 52.3 mV dec-1 toward the hydrogen evolution reaction (HER) in alkaline solution. Concurrently, Ni/MoO2@NF-E also maintains excellent stability after 120 h of electrolysis or 5000 cyclic voltammetry cycles. The experimental and density functional theory (DFT) results indicate that the enhanced HER performance of Ni/MoO2@NF-E should be ascribed to the porous structure in the Ni/MoO2 nanorods providing more active catalytic site, the moderate Gibbs free energy of hydrogen adsorption (ΔGH*), as well as strong synergistic effect between Ni and MoO2. This work provides an efficient route for developing HER electrocatalysts in alkaline media.