Structural modifications in metal–organic frameworks for CO2 adsorption and sensing through sustainable synthesis and emerging designs

1. Abstract Monitoring CO 2 levels in outdoors and indoor environments becomes crucial. Despite numerous commercially available sensors that are usually based on organic polymer or inorganic semiconductor materials that have limited response at lower temperatures. Recently, MOFs have emerged as one of the most promising candidates for CO 2 sensing materials due to their tunable structural properties. These materials consist of metal ions or clusters coordinated with chemically tunable organic linkers. This modular design yields crystalline frameworks with very high surface areas and precisely defined pore structure. Host-guest interactions found in MOFs are unique and highly responsive to physical and chemical interactions, which can be successfully used to address the major issues in CO 2 sensing, such as fast response, high sensitivity, and enhanced selectivity. This review is dedicated to the synthesis methods, classification, and fundamental structural changes of MOFs that directly affect sensing properties of MOFs. The functionalization strategies like amine grafting, metal doping, and development of composites with conductive materials are vital for efficient sensor performance. The main constraints of MOF-based CO 2 sensors are discussed in a systematic manner. The analysis is guided by fundamental research questions related to structural optimization, transduction mechanisms, and pathways for improving overall sensing performance. Revealing the current problems and presenting possible solutions, this paper gives a clear understanding of the direction in which MOF-based gas sensing technologies will evolve in the future.