Highly Distorted High-Entropy Alloy Aerogels for High-Efficiency Hydrogen Oxidation Reaction

The development of efficient electrocatalysts for alkaline hydrogen oxidation reaction (HOR) is essential for anion exchange membrane fuel cells and advancing the hydrogen economy. Herein, we demonstrated PtRuRhPdIr high-entropy alloy aerogels (HEAAs) with highly distorted structure as efficient HOR electrocatalysts and realized effective control of PtRu-based metallic aerogels (MAs) with elemental components ranging from two to seven. Specially, PtRuRhPdIr HEAAs on carbon (PtRuRhPdIr HEAAs/C) exhibit excellent HOR activity, with Pt group metal (PGM)-normalized mass activity (5.75 A mg_PGM^-1) at 50 mV and exchange current density normalized by electrochemical surface area (0.69 mA cm^-2), approximately 16.9 and 4.1 times that of the commercial Pt/C (0.34 A mg_PGM^-1, 0.17 mA cm^-2), respectively. The mechanism study shows that the highly distorted PtRuRhPdIr HEAAs provide abundant unsaturated sites for HOR, and the synergistic effect of multiple-active sites balances the adsorption of H* and *OH, boosting the HOR performance.