Here, micron-sized high-entropy alloy (HEA) electrocatalysts (FeCoNiMoCr, Cr-HEA; FeCoNiMoCu, Cu-HEA) with dual-phase heterostructures were fabricated by mechanical alloying and subsequently loaded onto nickel foam (NF) to form the working electrode, exhibiting excellent oxygen evolution reaction (OER) performance. Specifically, the Cr-HEA/NF exhibits an overpotential of 271 mV at current density of 10 mA/cm² and a small Tafel slope of 69.1 mV/dec in 1 mol/L KOH solution, outperforming the performance of Cu-HEA/NF, commercial RuO₂/NF and bare NF. HEA catalysts achieve outstanding long-term stability, as evidenced by chronopotentiometry (1 mol/L KOH for 48 h @10 mA/cm² and 6 mol/L KOH at 85 ℃ for 100 h @500 mA/cm²) and chronoamperometry (1 mol/L KOH for 100 h @100 mA/cm²). The impressive OER activity and stability of Cr-HEA can be attributed to the highly heterogeneous nested interfaces between amorphous and metastable nanocrystals, as well as the in-situ formation of multiphase structures. Notably, both density functional theory calculations and experimental results demonstrate that the synergistic interactions among the metal active sites in HEA collectively regulate the adsorption and desorption of oxygen-containing intermediates, thereby enhancing the OER catalytic activity. Specifically, the Cr-HEA presents a lower Gibbs free energy change during the transformation from O∗ to OOH∗, resulting in a reduced overpotential.

Highly active and stable electrocatalysts to produce hydrogen through water splitting are crucial for clean energy systems but are still challenging. Herein, a novel self-templating strategy was proposed to synthesize one-dimensional nanoporous RhNi alloy nanowires through combining metallurgical eutectic solidification and microalloying with chemical dealloying. In-situ X-ray diffraction and ex-situ characterizations reveal that the Al matrix served as a template to guide the growth of the Al₃(Ni, Rh) nanowires during eutectic solidification of Al-Ni-Rh precursor and was completely removed in the dealloying process. Meanwhile, the nanowire morphology could be well retained and the dealloying of Al₃(Ni, Rh) led to the formation of nanoporous RhNi alloy nanowires. The length scale of the RhNi nanowires could be facilely regulated by changing the solidification conditions. More importantly, the RhNi catalysts show excellent electrocatalytic activity and stability towards hydrogen evolution reaction in both acidic and alkaline media, which has been rationalized by density functional theory calculations.