Activating Ni via heterostructure-induced electron deficiency and spatial intermediate coupling for enhanced alkaline HER/HOR

The development of hydrogen energy conversion technology offers a solution to the global energy crisis. Hydrogen evolution reaction (HER) and hydrogen oxidation reaction (HOR) are essential for hydrogen production and utilization. Ni-based catalysts are promising alternatives to Pt-group catalysts under alkaline conditions. However, pure Ni exhibits low activity due to H 2 O dissociation/formation limitations in the rate-determining Volmer step. To overcome this bottleneck, we present a heterostructure-induced electron modulation strategy to regulate the spatial proximity of key intermediates within the inner Helmholtz plane, thereby facilitating Volmer step kinetics. Electron depletion at the Ni site shifts its d -band center upward, enhancing the adsorption of *H, *OH, and *H 2 O. This electronic tuning brings *H and *OH closer and elongates the H–OH bonds in *H 2 O, effectively reducing the Volmer barrier, as confirmed by density functional theory (DFT) and in-situ Raman spectroscopy. We demonstrate this concept using a representative heterostructure of nickel and tungsten nitride on nickel foam (Ni/WN@NF), which exhibits excellent electrocatalytic activity, requiring only 20 mV overpotential to achieve 10 mA cm −2 for HER and reaching an exchange current density of 3.99 mA cm −2 for HOR. This work offers a generalizable interfacial approach for modulating local chemical environments in alkaline hydrogen electrocatalysis.