Self-derived, high-mechanical-strength polymetallic phosphides microsheet heterostructures for industrial-scale high-current-density water-splitting†

Abstract

Developing nanoarray microstructure catalysts to amplify catalytic active sites has been a prevalent strategy to achieve effective water electrolysis. However, the stability of electrodes is severely affected by the bubble bombardment at industrial conditions. To address this issue, we synthesized a Fe–CoNiP/NCF (Fe–CNP/NCF) bifunctional catalyst with heterogeneous microsheet arrays on nickel cobalt foam (NCF) using Fe³⁺ as an inducer through cation exchange and low-temperature phosphorization. The optimized Fe–CNP/NCF catalyst exhibited outstanding HER (η₁₀₀₀ = 195 mV) and OER (η₁₀₀₀ = 278 mV) activities, benefiting from the integration of abundant active sites on the hierarchical microsheets, where the doping of Fe promoted the formation of active species for the OER. In particular, accelerated mechanical strength tests demonstrated that the self-derived multidimensional catalyst possessed high mechanical robustness, thereby ensuring electrode resistance to withstand bubble impact under high current densities. As a proof of concept, in an industrial environment (6 M KOH, 80 °C), the dual-electrolyzer assembled with Fe–CNP/NCF sustained electrolysis for 200 h at a current density of 0.5 A cm⁻², with a minimal rate of voltage loss (1.5 × 10⁻⁴ V h⁻¹), which demonstrated prolonged catalytic durability and structural integrity. This work provides new insights and approaches for developing nanoscale catalysts with high mechanical strength for large-scale industrial water electrolysis.