Self-Supported Nanoporous High-Entropy Alloy Electrodes with W-Modulated Surface Reconstruction for Alkaline Hydrogen Evolution

Efficient and durable non-noble catalysts are crucial for alkaline hydrogen evolution (HER), and high-entropy alloys (HEAs) offer a promising platform due to their multicomponent synergy and tunable surface chemistry. Herein, self-supported nanoporous high-entropy alloy electrodes, Fe35Co25Ni30Mo10 and Fe35Co25Ni30Mo7W3, were prepared by arc melting followed by electrochemical dealloying in 1 M HCl. XRD results show that both alloys retain an FCC framework after dealloying, whereas SEM reveals that W promotes a more continuous sponge-like nanoporous structure. In 1 M KOH, dealloyed Fe35Co25Ni30Mo7W3 shows enhanced HER activity, requiring an overpotential of 178 mV at 10 mA cm−2, which is lower than that of dealloyed Fe35Co25Ni30Mo10 and the precursors. Dealloyed Fe35Co25Ni30Mo7W3 also exhibits faster kinetics (Tafel slope 98.5 mV dec−1; Rct 3.33 Ω) and a larger Cdl (19.2 mF cm−2) than dealloyed Fe35Co25Ni30Mo10. These results highlight W-enabled dealloying-induced reconstruction as an effective route to robust nanoporous HEA electrodes for alkaline HER.