Amorphous‐Crystalline Heterostructured Nanoporous High‐Entropy Alloys for High‐Efficiency pH‐Universal Water Splitting

Abstract Developing high‐efficiency durable electrocatalysts in wide pH range for water splitting is significant for environmentally‐friendly synthesis of renewable hydrogen energy. Herein, a facile method by dealloying designable multicomponent metallic glass precursors is reported to synthesize amorphous‐crystalline heterostructured nanoporous high‐entropy alloys (AC‐HEAs) of CuAgAuPtPd, CuAgAuIrRu, and CuAgAuPtPdIrRu, heaped up by nanocrystalline particles with an average size of 2‐3 nm and the amorphous glued phase. The synthesized AC‐HEA‐CuAgAuPtPd owns highly catalytic performances for hydrogen evolution reaction (HER), with 9.5 and 20 mV to reach 10 mA·cm −2 in 0.5 m H 2 SO 4 and 1.0 m KOH, and AC‐HEA‐CuAgAuIrRu delivers 208 and 200 mV for oxygen evolution reaction (OER). Moreover, a two‐electrode electrolyzer made of the AC‐HEA‐CuAgAuIrRu bifunctional electrodes exhibit a low cell voltage of 1.48 and 1.49 V in the acidic and alkaline conditions at 10 mA·cm −2 for overall water splitting. Combining the enhanced catalytic activities from nanoscale amorphous structure and atom‐level synergistic catalyst in AC‐HEAs provides an effective pathway for pH‐universal electrocatalysts of water splitting.