Selective and sustainable electrochemical CO2 conversion to formate over a copper-promoted industrial residue (UGSO) electrocatalyst

Electrochemical CO 2 reduction has emerged as an effective approach for converting CO 2 into value-added chemicals, contributing to both carbon mitigation and resource utilization. Nevertheless, synthesis of efficient and stable electrocatalysts from low-cost and sustainable materials remains a big challenge. Herein, we report a novel copper electrocatalyst supported on a double ball-milled (DBM) UpGraded Slag Oxide (UGSO, a waste from the iron and titanium industry), for efficient CO 2 conversion to formate. The developed xCu/UGSO_DBM electrocatalysts (x = 2.5-50 wt%) were characterized by BET, XRD, SEM/EDS, and XPS analyses. 15Cu/UGSO_DBM exhibited excellent performance, achieving a Faradaic efficiency of 83.1% at −0.62 V vs. RHE and maintaining stable operation for 6 h. Chronopotentiometry at −60 mA further confirmed the excellent durability of the electrode. XPS analysis revealed in situ reduction of surface Cu 2+ species into more catalytically active Cu + /Cu 0 states. The enhanced activity is attributable to the optimized Cu dispersion along with the synergistic interactions with the multimetallic oxide matrix of UGSO that improves the charge transfer and stabilizes the key intermediates. Overall, this work establishes a high-performance waste-derived Cu electrocatalyst for selective CO 2 -to-formate conversion at a low overpotential and provides a sustainable approach to designing electrocatalysts in line with circular economy principles. • Direct valorization of metallurgical residue as catalytic support for CO 2 electrochemical conversion. • Selective CO 2 electroreduction to formate by novel xCu/UGSO_DBM electrocatalysts. • Improved charge transfer and intermediate stabilization through synergistic interactions of Cu and multimetallic support. • 15Cu/UGSO_DBM exhibits 83.1% Faradaic efficiency at −0.62 V vs. RHE with stable operation for 6 h.