High entropy alloys (HEAs) are promising as multifunctional electrocatalysts owing to their inherent compositional and structural complexity and thus the multiple active sites for different reactions. Herein, a bifunctional porous HEA binder-free electrode has been designed and fabricated by selectively etching eutectic dual-phase microstructures. The AlCrFeCoNiW HEA consisting of FCC and ordered BCC phase was dealloyed with aluminum-enriched BCC phase being removed effectively to construct three-dimensional porous architecture. The porous HEA electrode exhibits excellent hydrogen evolution reaction activity (overpotential of 101 mV at current density of 10 mA cm-2), oxygen evolution reaction activity (overpotential of 270 mV at current density of 50 mA cm-2), along with outstanding stability under industrial condition. The in-situ electrochemical infrared spectra illustrate that the great electrochemical water splitting performance in alkaline electrolyte may be closely related to the enhanced interactions between the electrode surface and absorbed water molecules. The first-principles calculations based on the density functional theory reveal an improvement in the intrinsic catalytic activity after dealloying process. This work combines the concept of HEA with multiple active sites for catalysis and selective etching tuned by eutectic microstructure, paving a new way in designing the low-cost self-supporting electrode for future sustainable energy applications.

Porous high-entropy alloys as high-performance bifunctional electrocatalysts for water splitting

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