HKUST-1-Derived Copper Oxide-Supported Silver Nanoparticles for Highly Selective and Efficient Electrocatalytic CO₂ Reduction

The selective and efficient electrochemical transformation of carbon dioxide (CO2) into valuable chemical products remains challenging in modern catalysis. Among various electrocatalysts, silver (Ag) has emerged as a highly promising candidate for CO2-to-CO conversion under ambient conditions, attributed to its superior catalytic performance, remarkable selectivity, and thermodynamically favorable reaction pathway. In this study, we introduce a series of Ag/CuxO/C electrocatalysts derived from MOF (HKUST-1), with the optimized Ag/CuxO/C4 demonstrating exceptional performance. At −0.70 VRHE, the Ag/CuxO/C4 catalyst demonstrates a low overpotential (η) of 245 mV, a high partial current density (jCO) of 41 mA cm–2, and a Tafel slope of 49 mV dec–1, indicating efficient charge transfer and favorable reaction kinetics. These attributes collectively enabled an outstanding CO Faradaic efficiency (FECO%) of ≈95%, underscoring the catalyst’s exceptional selectivity and performance. The catalyst exhibited outstanding durability, maintaining its high FECO over 10 h of operation at various applied potentials without significant current loss. The qualitative and quantitative testing of the observed gaseous and liquid products using GC-MS, GC-TCD, and GC-FID confirmed the exceptional selectivity of Ag/CuxO/C4 for CO production. The PdCl2 strip method further validated the presence of CO, highlighting the catalyst’s specificity. This research highlights the potential of Ag/CuxO/C4 composite materials, characterized by controlled particle size and low noble metal loading, as highly efficient and durable catalysts for electrocatalytic CO2-to-CO.