Carbon Nanosheet-Supported Ag/CoO Catalysts for Efficient CO2 Reduction

Silver-based composites have been widely recognized for their efficiency as catalysts in the electrochemical reduction of carbon dioxide (eCO2RR). However, several inherent limitations impede their broad-scale application. This study presents a novel, efficient, and cost-effective silver-based electrocatalyst for eCO2RR. The resulting hybrid catalyst consists of cobalt oxide (CoO) and silver nanoparticles (Ag NPs) uniformly distributed over nitrogen-doped carbon nanosheets (NCNS) denoted as Ag/CoO/NCNS. The novel material is synthesized using ZIF-12 as a precursor, allowing for direct nitrogen doping during pyrolysis, which effectively prevents the aggregation and stacking of carbon nanosheets. Among the series of catalysts synthesized, Ag/CoO/NCNS1, with an optimum silver-to-support ratio, exhibits superior activity with a low overpotential (η) of 130 mV and a current density of 53 mA cm–2. Furthermore, it achieves the highest Faradaic efficiency of 87% at −0.5 VRHE. The increased catalytic activity can be attributed to the transfer of charge from highly conductive CoO/NCNS to the Ag metal. The main active sites on the surface of Ag NPs activate CO2 molecules and stabilize the COOH* intermediate, as is evident by its lower Tafel slope value of 110 mV dec–1. Ag/CoO/NCNS1 has also shown exceptional stability under an extended electrolysis process and achieved an enhanced electrochemical active surface area (ECSA) value of approximately 293.1 cm2. These results highlight the potential of Ag/CoO/NCNS1 as a promising catalyst for large-scale CO2 reduction applications.