Tailoring Cu Content in High-Entropy Alloys for Superior Bifunctional Electrocatalysis in Alkaline Water Splitting

Electrocatalytic technology serves as a critical pathway for clean energy conversion, where high-entropy alloys demonstrate outstanding catalytic performance owing to their unique multi-principal-element design. This work systematically investigates Cu x (CoCrNiFe) 100-x HEAs as cost-effective bifunctional catalysts for both freshwater and seawater electrolysis. The optimized Cu 50 (CoCrNiFe) alloy exhibits excellent catalytic activity with low overpotentials of 248.3   mV for HER and 327   mV for OER at -10 mA cm -2 in alkaline freshwater, along with remarkable stability (<5% decay after 24   hours). Notably, in alkaline seawater electrolyte, it achieves even better HER performance (234   mV) while maintaining comparable OER activity, and demonstrates exceptional 50-hour durability in overall water splitting tests. These findings not only provide new insights into HEA-based catalyst design but also highlight the great potential of such materials for practical large-scale hydrogen production from seawater resources, representing a significant step toward sustainable energy solutions.