Laser-Induced High-Entropy Alloys as Long-Duration Bifunctional Electrocatalysts for Seawater Splitting

Abstract

Electrocatalytic seawater splitting has garnered significant attention as a promising approach for eco-friendly, large-scale green hydrogen production. Development of high-efficiency and cost-effective electrocatalysts remains a frontier in this field. Herein, we report in situ, rapid synthesis of FeNiCoCrRu high-entropy alloy nanoparticles (HEA NPs) by direct CO₂ laser induction of metal precursors on carbon paper under ambient conditions. Due to the induced ultrahigh temperature and ultrafast heating/quenching rates, the HEA NPs with sizes ranging from 5 to 40 nm possesses uniform phase homogeneity. FeNiCoCrRu HEA NPs exhibit exceptional bifunctional electrocatalytic activities, delivering overpotentials of 0.148 V at 600 mA/cm² for hydrogen evolution reaction and 0.353 V at 300 mA/cm² for oxygen evolution reaction in alkaline seawater. When assembled to an electrolyzer, it shows a negligible voltage increase at 250 mA/cm² after over 3000-hour operation. This superior performance can be attributed to the high-entropy design, large electrochemical specific area, excellent chemical and structural stability. Operando Raman spectroscopy study discloses the Ni and Ru sites serve as active sites for hydrogen evolution, while Ni site acts as active sites for oxygen evolution. This work demonstrates a laser-induced eco-friendly nanomaterials synthesis. The systematic studies offer an in-depth understanding of HEA design and its correlation with high-efficiency seawater splitting.