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.