Nanotwinning of the Nickel Nitride Nanosheets for Robust Hydrogen Oxidation Electrocatalysis.

Nanotwinning of heterogeneous electrocatalysts represents an attractive tool to reconfigure the interfacial microenvironments with refined delivery and adsorption behaviors of reactants for high-performance electrocatalysis. Here, we describe a facile iridium-mediated-nanotwinning strategy to synthesize nanotwinned Ir-atom-substituted Ni₃N nanosheets with compatibly promoted hydroxyl delivery and adsorption as robust electrocatalysts for alkaline hydrogen oxidation reaction (HOR). These nanotwinned architecture can weaken the interfacial electric field with improved connectivity of hydrogen-bond network for enhanced hydroxyl delivery, and also stimulate the valence-electron delocalization with strengthened Ni 3d-O 2p valence-electron-orbital interaction for enhanced hydroxyl adsorption, together with elevated electrical conductivity. Accordingly, the mass activity of the nanotwinned Ir-atom-substituted Ni₃N nanosheets was five times higher than that of commercial Pt/C toward alkaline HOR. This strategy sheds light on the rational design of high-performance electrocatalysts with controllable delivery and adsorption behaviors of reactants by nanotwinning.