One‐Step Controllable Synthesis of Catalytic Ni4Mo/MoOx/Cu Nanointerfaces for Highly Efficient Water Reduction.

Currently, in addition to the electroactive non‐noble metal water‐splitting electrocatalysts, a scalable synthetic route and simple activity enhancement strategy is also urgently needed. In particular, the well‐controlled synthesis of the well‐recognized metal–metal nanointer face in a single step remains a key challenge. Here, the synthesis of Cu‐supported Ni4Mo nanodots on MoOx nanosheets (Ni4Mo/MoOx) with controllable Ni4Mo particle size and d‐band structure is reported via a facile one‐step electrodeposition process. Density functional theory (DFT) calculations reveal that the active open‐shell effect from Ni‐3d‐band optimizes the electronic configuration. The Cu‐substrate enables the surface Ni–Mo alloy dots to be more electron‐rich, forming a local connected electron‐rich network, which boosts the charge transfer for effective binding of O‐related species and proton–electron charge exchange in the hydrogen evolution reaction. The Cu‐supported Ni4Mo/MoOx shows an ultralow overpotential of 16 mV at a current density of 10 mA cm−2 in 1 m KOH, demonstrating the smallest overpotential, at loadings as low as 0.27 mg cm−2, among all non‐noble metal catalysts reported to date. Moreover, an overpotential of 105 mV allows it to achieve a current density of 250 mA cm−2 in 70 °C 30% KOH, a remarkable performance for alkaline hydrogen evolution with competitive potential for applications. [ABSTRACT FROM AUTHOR]