Integrated CO₂ capture and methanation over inorganic dual-functional materials: from mechanism to reactor

The urgency of climate mitigation has shifted CO₂ management from isolated capture or utilization to integrated carbon cycling. In situ CO₂ methanation offers a chemically coherent route by converting captured CO₂ into methane through hydrogenation with renewable hydrogen, eliminating intermediate purification and compression. Inorganic dual-functional materials (DFMs), which integrate CO₂ adsorption and catalytic hydrogenation functions within a single matrix, are central to enabling this concept by synchronizing capture and conversion. This review begins with a systematic overview of CO₂ capture, with a focus on inorganic solid-state materials and their inherent performance trade-offs. It then examines the conceptual framework and latest advances in integrated carbon capture and conversion (iCCC) over DFMs, focusing on mechanistic understanding, interfacial synergy, intermediate speciation, and material design strategies. Subsequently, the review explores process intensification strategies for in situ methanation, from reactor configurations to system integration. This review focuses on inorganic DFMs as the key enabler, delivering mechanistic understanding and intensification strategies to advance efficient integrated CO₂ capture and methanation.