Interfacial engineering of CuSe₂/FeSe₂ heterojunctions for water splitting: a pathway to high-performance hydrogen and oxygen evolution reactions

The efficiency of green hydrogen production <i>via</i> water electrolysis is critically constrained by high energy barriers, particularly during the oxygen evolution reaction (OER). In this study, CuSe₂/FeSe₂ heterojunctions are introduced as cost-effective and highly active bifunctional electrocatalysts for overall water splitting. Leveraging the abundant and tunable properties of Cu- and Fe-based chalcogenides, this work demonstrates how charge redistribution and interfacial electronic coupling in the heterostructure significantly enhance catalytic activity. High surface area CuSe₂/FeSe₂ heterojunctions enhance hydrogen and oxygen adsorption and accelerate charge transfer, achieving low overpotentials (666 mV for the HER and 490 mV for the OER at 10 mA cm^-2), a high OER current density (135 mA cm^-2), and a reduced Tafel slope (137 mV dec^-1). The catalyst maintained stable performance over 24 hours of continuous operation at 10 mA cm^-2, confirming its structural robustness and practical viability. These findings position CuSe₂/FeSe₂ heterojunctions as promising candidates for scalable, sustainable hydrogen production and advanced electrochemical energy technologies.