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 mu g 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 degrees 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.