100% Conversion of CO2–CH4 with Non-Precious Co@ZnO Catalyst in Hot Water

Abstract The combination of solar energy and natural hydrothermal systems will innovate the chemistry of CO 2 hydrogenation; however, the approach remains challenging due to the lack of robust and cost-effective catalytic system. Here, Zn which can be recycled with solar energy-induced approach was chosen as the reductant and Co as catalyst to achieve robust hydrothermal CO 2 methanation. Nanosheets of honeycomb ZnO were grown in situ on the Co surface, resulting in a new motif (Co@ZnO catalyst) that inhibits Co deactivation through ZnO-assisted CoO x reduction. The stabilized Co and interaction between Co and ZnO functioned collaboratively toward the full conversion of CO 2 –CH 4 . In situ hydrothermal infrared spectroscopy confirmed the formation of formic acid as an intermediate, thereby avoiding CO formation and unwanted side reaction pathways. This study presents a straightforward one-step process for both highly efficient CO 2 conversion and catalyst synthesis, paving the way for solar-driven CO 2 methanation.