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 via 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.