Aluminum-Triggered Dealloying for Hierarchical Porous High-Entropy Alloy Electrodes Enabling Industrially Stable Oxygen Evolution

The oxygen evolution reaction (OER) is essential for advancing water electrolysis toward green hydrogen production. However, its intrinsically sluggish kinetics and the stringent durability required under industrial conditions remain major bottlenecks. Herein, a free-standing hierarchical porous Ni–Fe–Co–Mn-Al (hp-NFCMA) high-entropy alloy electrode is fabricated via an Aluminum (Al) -triggered electrochemical dealloying process. The Al-triggered dealloying behavior constructs a hierarchical architecture featuring intragranular nanopores and microscale intergranular trenches. This structure enhances reaction kinetics and enables rapid mass transport, guiding an ordered surface reconstruction into a uniform and gradually densifying thin active layer, which effectively suppresses excessive and disordered accumulation, thereby preserving the structural integrity of the catalyst. Meanwhile, residual Al modulates the electronic structure to boost lattice-oxygen activity. These synergistic effects endow the electrode with high intrinsic activity and exceptional durability. Specifically, the hp-NFCMA electrode achieves a low overpotential of 322 mV at 500 mA cm –2 and sustains stable operation for over 1500 h at an industrially relevant current density of 1000 mA cm –2 under simulated industrial conditions (6 M KOH, 85 °C). Thus, the hp-NFCMA electrode offers a promising combination of high activity and outstanding durability for practical alkaline water electrolysis.