Interstitial boron-doped Ni₄Mo nanoarray catalyst boosts stable hydrogen evolution reaction

Designing a strategy to make the intrinsic activity of NiMo-based catalysts while being able to achieve long-term stable hydrogen production at ampere-level current densities is important for their development in AEM elec-trolyzers. Herein, interstitial boron atom-doped Ni4Mo is designed to obtain the catalyst with excellent alkaline HER properties. B4.7-Ni4Mo/NF exhibits a small overpotential of 135.2 mV at 1000 mA cm-2 and a high turnover frequency (TOF) value of 6.14 s-1 at 100 mV in alkaline HER, which very close to that of Pt/C (6.86 s-1). The catalyst requires only 1.73 V to achieve a current density of 1.0 A cm-2 in AEM electrolyzer at 60 degrees C and is stable for 800 h. Experimental and theoretical calculations reveal that interstitial boron doping not only optimizes the electronic structure to optimize H* adsorption and promote the water dissociation but also inhibits the disso-lution of Mo by forming boron-metal bond.