FeCoP/Cu₂S flake-like clustered heterostructure, hierarchically engineered for benchmark trifunctional electrocatalytic performance and long-term alkaline stability

Abstract

We present a high-performance trifunctional electrocatalyst comprising FeCoP nanoflakes integrated on copper sulfide (Cu2S) nanorods array grown directly on copper foam. This hierarchically engineered FeCoP/Cu2S architecture provides a conductive, binder-free network with abundant active sites and strong interfacial synergy. As a result, the FeCoP/Cu2S catalyst achieves outstanding activity for all three key reactions: low overpotentials of 162 mV (HER) and 300 mV (OER) at 100 mA cm⁻², and an ORR half-wave potential of 0.81 V (limiting current 4.8 mA cm⁻²) in alkaline media. When assembled in a two-electrode alkaline water electrolyzer, FeCoP/Cu2S requires only 1.726 V to drive 100 mA cm-2 and maintains stable performance over 16 h. Also, in an alkaline seawater, it reaches 100 mA cm-2 at 1.959 V, demonstrating remarkable performance in corrosive media. Moreover, FeCoP/Cu2S exhibits an exceptionally small oxygen bi-functionality gap (ΔE = 0.67 V between OER and ORR), outperforming most state-of-the-art non-precious catalysts. These results highlight how strategic architectural and compositional engineering can yield a cost-effective, tri-functional electrocatalyst, offering a promising solution for integrated energy conversion systems such as overall water splitting and rechargeable metal-air batteries.