摘要
Low-temperature CO2 methanation remains challenging due to the high activation barrier for CO bond cleavage and the need for catalysts that can concurrently facilitate CO2 adsorption, intermediate stabilization, and rapid hydrogenation. Here we present a carrier-free, vacancy-engineered ZIF-67 material (ZIF08-H) that incorporates spatially adjacent CoN3, nitrogen-vacancy (NV), and oxygen-vacancy (OV) sites generated through a hydrothermal self-assembly route. These coupled defects create co-functional domains that enhance CO2 polarization, promote both formate- and CO-mediated pathways, and accelerate *Oads removal through H2O formation, thereby preventing CO accumulation (one of the main deactivation routes) in Co-based methanation systems. Unlike conventional ZIFs that lose structural integrity near 300 °C, ZIF08-H maintains catalytic continuity at this temperature, enabling CH4 and CO production rates of 27,546.3 and 17,810.8 mmol g−1 h−1, respectively. During cyclic operation, CH4 productivity increases to 57,982.4 mmol g−1 h−1 by the 35th cycle and remains stable over subsequent cycles before gradually declining. These results demonstrate that a defect-modulated, unmodified ZIF-67 framework can function as a thermally resilient, standalone CO2 methanation catalyst. Obtained results address the long-standing limitations of pristine ZIFs and providing a new direction for vacancy-engineered MOF catalysts in low-carbon energy conversion.
•Vacancy-engineered ZIF08-H couples Co–N3–NV and Co–OV sites for efficient low-temperature CO₂ hydrogenation.•AP-XPS reveals dual-site cooperation: Co-N3-NV cleaves CO2; Co-OV removes Oads via reversible H2O formation.•Defects stabilize ZIF08-H up to 300 °C, preventing Co sintering seen in ZIF08-M.•ZIF08-H achieves high CH4 productivity (57,982.4 mmol g-1 h-1) via formate- and CO-mediated pathways.•Demonstrates a rare carrier-free, thermally resilient MOF catalyst for CO2 methanation.