Surface Reconstruction of Iron–Cobalt–Nickel Phosphides to Achieve High-Current-Density Water Oxidation Performance

The development of efficient and low-cost OER electrocatalysts that can achieve high current density and durable stability for the practical application of energy conversion devices remains a challenge. Herein, a Fe–Co–Ni-based phosphide heterojunction integrated electrocatalyst (FeCoNiP/NF) had been obtained by a facile hydrothermal-phosphating strategy. The results indicate that superior OER performance at a high current density in 1 M KOH has been achieved for the FeCoNiP/NF catalyst, which exhibits low overpotentials of 281 and 318 mV at 500 and 1000 mA cm–2, respectively. Furthermore, this catalyst also shows excellent activity and stability at industrial-grade KOH concentrations (30 wt %). The overpotentials are as low as 217 and 233 mV at 500 and 1000 mA cm–2, respectively, and they can be maintained for 48 h at 500 mA cm–2 with just 4% attenuation, which is one of the most efficient non-noble-metal-based OER catalysts at high current densities. The strong binding of P to metals and the self-supported architecture are beneficial to improve the conductivity and stability of the catalyst. Moreover, the multiple heterointerfaces will accelerate surface charge transport, and the formed oxyhydroxide active species by in situ phase reconstruction can significantly enhance the OER performance of the FeCoNiP/NF catalyst. This study not only synthesizes an efficient OER catalyst with a low overpotential at a high current density but also discusses the surface reconstruction of the catalysts in detail, which provides a distinct perspective for the design of high-performance electrocatalysts.