A robust and highly active bimetallic phosphide/oxide heterostructure electrocatalyst for efficient industrial-scale hydrogen production

Abstract

Efficient and durable high-current-density bifunctional electrocatalysts are vital for cost-effective production of alkaline water electrolyzers (AWEs) on an industrial scale. However, existing commercial catalysts, such as Raney Ni which requires over 2.5 V for just 500 mA cm−2, fail to achieve high current densities with low cell voltages. In this study, we introduce a bifunctional RuP2/Ni5P4/NiMoO4 heterostructure electrocatalyst, synthesized via a facile hydrothermal method, followed by the controlled addition of ruthenium (Ru) and subsequent phosphorization. This process yielded (Ru, Ni) phosphides and NiMoO4 with a moderate weight percentage and mass loading of Ru content, approximately 1.02 wt% and 61 μg cm−2, respectively. The synergistic effect of these phosphides and bimetallic oxides significantly improves water dissociation, as well as the hydrogen and oxygen evolution reaction (HER and OER) performances. Under industrial conditions (80 °C and 6 M KOH), our catalyst achieves low overpotentials of 273 mV for HER and 390 mV for OER at 2000 mA cm−2, outperforming commercial Pt/C and RuO2 catalysts. Additionally, in an AWE, our catalyst maintains a low operating voltage of 1.76 V for 1 A cm−2, with consistent performance over 100 h at 500 mA cm−2. It records an electricity consumption of 3.97 kW h Nm−³ and an electrolyzer efficiency of 89.1%, underscoring its potential for cost-effective industrial applications. Furthermore, accelerated degradation tests under variable current loads show no significant change in cell voltage and high-frequency resistance (HFR), demonstrating robustness for intermittent energy sources. This work proposes a novel design principle for high-performance electrocatalysts, significantly reducing reliance on noble metals and offering a robust, efficient solution for industrial-scale hydrogen production. © 2024 Elsevier Ltd