Karya Sinulingga, Makmur Sirait, Eva Marlina Ginting
Electrochemical CO₂ reduction reaction (eCRR) into multicarbon (C₂) product presents a sustainable strategy for carbon recycling and renewable energy conversion. Herein, oxide-derived Cu foam (CF-x) electrodes were fabricated through a facile freeze-humidification followed by calcination at 200–600 °C to elucidate the structure–activity relationship between surface phase composition and C₂H₄ selectivity. Comprehensive characterization revealed that temperature-driven oxidation gradually transformed metallic Cu into mixed Cu₂O/CuO phases on the surface, forming abundant Cu⁰–Cu⁺–Cu²⁺ interfaces. The CF-4 electrode (400 °C) exhibited the most balanced interfacial structure, yielding the lowest charge-transfer resistance (2.9 Ω) and the largest electrochemically active surface area (1050 cm²). These synergistic interfaces effectively stabilized *CO intermediates and promoted C–C coupling, achieving a C₂H₄ Faradaic efficiency of 25.7% and a production rate of 8.1 mmol/h.cm² at 100 mA/cm². Moreover, CF-4 maintained structural and catalytic stability over 20 h of continuous electrolysis, with only a slight decline in C₂H₄ selectivity. This work highlights the critical role of phase-engineered Cu/Cu₂O interfacial synergy in governing C₂ product formation and demonstrates a scalable, low-cost strategy for designing durable oxide-derived Cu catalysts for efficient CO₂-to-C₂H₄ conversion. © 2026 The Authors
Department of Physics, State University of Medan, Medan City, Indonesia
