Synergistic mechanochemistry and facet engineering boost conversion of dilute CO2 from industrial flue gases

Efficient conversion of dilute CO 2 into valuable products remains a significant challenge due to the low CO 2 concentrations (5–10%) in industrial flue gases, which are accompanied by inert gases and impurities. This results in low partial pressures, limited mass transfer, and dominant side reactions, undermining the efficiency and selectivity of CO 2 reduction reactions (CO 2 RR). To address this, we present a synergistic mechanochemistry–facet engineering strategy for efficient and selective CO 2 RR under ambient conditions using diluted CO 2 streams. By combining ultrasonic cavitation with mechanical stirring and exposing Cu 2 O (111) facets, the system achieves a CO yield of 1865.6 µmol g cat –1 , CO selectivity of 96.4%, and CO 2 conversion efficiency of 13.9% within one hour. These results surpass most previously reported systems for CO 2 reduction using low-concentration CO 2 streams. Mechanochemical activation enhances mass transfer and accelerates reaction kinetics, while facet engineering optimizes CO 2 adsorption and facilitates intermediate conversion. Density functional theory (DFT) calculations further reveal facet-dependent adsorption configurations and mechanochemical CO 2 RR pathways, clarifying the origins of the improved activity and selectivity. This approach provides a scalable solution for CO 2 conversion in low-concentration CO 2 environments, holding practical value in advancing industrial flue gas treatment and carbon capture and utilization (CCU) technologies.