Boosting Dual Hydrogen Electrocatalysis with Pt/NiMo Catalysts: Tuning the Ni/Mo Ratio and Minimizing Pt Usage

The development of efficient platinum group metal-free (PGM-free) catalysts for the hydrogen evolution reaction (HER) and the hydrogen oxidation reaction (HOR) is essential for advancing hydrogen-based energy technologies. In this study, NixMo100−x composites supported on Carbon Ketjenblack EC-300J (CK) were synthesized via thermal reduction under a controlled Ar/H2 (95:5) atmosphere to investigate the effect of the Ni/Mo molar ratio on electrocatalytic performance. Structural and morphological analyses by XRD and TEM confirmed the formation of the NiMo alloys and carbide phases with controlled particle size distributions (~18 nm), while BET measurements revealed specific surface areas up to 124.69 m2 g−1 for the Pt-loaded samples. Notably, the 3% Pt/Ni90Mo10-CK catalyst exhibited outstanding bifunctional activity in a half-cell configuration, achieving an overpotential of 65.2 mV and a Tafel slope of 41.6 mV dec−1 for the HER, and a Tafel slope of 32.9 mV dec−1 with an exchange current density of 1.03 mA cm−2 for the HOR. These results demonstrate that compositional tuning and minimal Pt incorporation synergistically enhance the catalytic efficiency, providing a promising platform for next-generation hydrogen electrocatalysts.