Ni/MoO2 heterostructure catalyst with synergistic active sites for efficient alkaline hydrogen evolution reaction: From active sites to intrinsic kinetics

One-step hydrothermal synthesis of cost-effective Ni/MoO 2 catalyst. • Kinetic model enables reliable reaction dynamics quantification. • Ni/MoO 2 shows exceptional HER activity with η 10 of 104 mV. • MoO 2 lowers H 2 O dissociation barrier, Ni promotes OH desorption. Facing the energy crisis and carbon neutrality demands, electrolytic green hydrogen is a key energy transition focus. This work developed a non-noble Ni/MoO 2 catalyst for alkaline hydrogen evolution reaction (HER), delivering 104 mV overpotential (10 mA cm −2 ) and 115.1 mV dec −1 Tafel slope. This is closely related to the Ni/MoO 2 heterostructure. MoO 2 acts as an efficient H 2 O dissociation active site (Δ G  = 0.16 eV), while Ni nanoclusters facilitate OH* desorption, reducing Δ G OH* from 0.21 eV (sole MoO 2 site) to 0.13 eV (synergized by Ni nanocluster). Regarding the H* intermediate, it exhibits comparable Δ G H* values (0.34 eV on MoO 2 and 0.36 eV on Ni/MoO 2 ), indicating H* directly evolves into H 2 over MoO 2 . Furthermore, intrinsic reaction kinetics were systematically studied at 20–40 °C, and an intrinsic kinetic model was established. This model can effectively predict elementary reaction rates and provides key kinetic data for future anion exchange membrane water electrolyzers (AEMWEs) design. Download: Download high-res image (275KB) Download: Download full-size image