Optimized ball milling synthesis of efficient NiMo bimetallic electrocatalysts for hydrogen evolution reaction in alkaline conditions

Hydrogen evolution reaction (HER) plays a pivotal role in sustainable energy solutions, enabling efficient hydrogen production as a clean fuel alternative. However, developing cost-effective and high-performance electrocatalysts for HER remains a significant challenge. This study explores the fabrication of a nanostructured NiMo alloy by a cost-effective and scalable ball milling process, obtaining a high-performance electrocatalyst for HER in alkaline conditions. Two methods, separate or simultaneous ball milling of Ni powder and Mo/MoO_x-based waste powder, are compared to evaluate their influence on the material physicochemical properties and catalytic activity. The NiMo nanostructures obtained by milling together the two powders exhibit remarkable improvements compared to the electrocatalyst prepared by mixing the separately milled powders, including a low overpotential of just 100 mV at a current density of 10 mA cm⁻² and enhanced electron transfer efficiency. Comprehensive morphological, chemical, and electrochemical analyses revealed the critical role of synergistic metal interactions and process optimization. This study demonstrates the significant potential of a precisely engineered ball milling approach for developing efficient and sustainable electrocatalysts for water splitting applications.