Ni–Mo nanostructure alloys as effective electrocatalysts for green hydrogen production in an acidic medium

Abstract

Achieving a net-zero emissions economy requires significant decarbonization of the transportation sector, which depends on the development of highly efficient electrocatalysts. Electrolytic water splitting is a promising approach to this end, with Ni–Mo alloys emerging as strong candidates for hydrogen production catalysts. This study investigates the electrodeposition of Ni and Ni–Mo nanostructured alloys with high molybdenum content onto low-carbon steel cathodes using a novel alkaline green lactate bath. Catalyst morphology, microstructure, and composition were characterized using SEM, XRD, XPS, and EDX. Results showed molybdenum content increased with current density, ranging from 40.14 wt% at 1.12 mA cm⁻² to 61.68 wt% at 5.56 mA cm⁻², with average particle sizes of 39.4 nm for Ni, 20.7 nm for Ni–2Mo (56% Mo), and 30.8 nm for Ni–4Mo (65% Mo). The alloys comprised tetragonal MoNi₄, metallic Ni, metallic Mo, and MoO₃ phases. Ni–4Mo exhibited superior HER performance in 0.5 mol L⁻¹ H₂SO₄, with the lowest Tafel slope (−113 mV dec⁻¹), highest exchange current density (1.250 mA cm⁻²), and good stability after 250 cycles. It also outperformed Ni–2Mo at −50 mA cm⁻², demonstrating its promise as a durable and efficient HER catalyst in acidic media.