Recent advances in MOF-based room-temperature gas sensors: dimensional nanostructure and advanced transduction mechanisms.

In the modern era, where ultra-low power gas sensing devices is in high demand due to government policies and people's consciousness, room-temperature sensing devices becomes very relevant. The conventional sensing devices usually operate at higher temperatures, mostly in the temperature range of 100°C - 450°C as the conventional metal oxide receptors show activated surface behavior in this regime. Elevated temperature helps in overcoming reaction barriers, improves adsorption-desorption kinetics, which has a direct impact on reversability of the device, reduces gas and moisture poisoning, and helps in a significant improvement in signal-to-noise ratio (SNR). However, it has several drawbacks, including high power consumption, material degradation, poor selectivity, safety concerns, system integration issue with CMOS as well as flexible substrates. Therefore, there is a quest for advanced functional materials which can detect gases at low temperature, preferably at room temperature. Metal Organic frameworks (MOF) which has several favourable properties like their high tunable porosity, strong but reversible adsorption behaviour, and chemical flexibility. Not to mention, they have exceptionally high surface area, intrinsic porosity for better molecular sieving, rich chemical functionality, ability to host conductive guests. Over it, the intelligent selection of ligand and metal nodes can be really beneficial in designing room-temperature sensing receptors. In this review, we have discussed different electronic transduction techniques beyond chemiresistive devices like capacitive, transistors, diodes. used for gas detection based on MOFs. All these discussion is done keeping mechanistic insights in place. Since all these devices are based on different nanostructures of MOF, a more detailed view on the different nanostructures like 0D,1D,2D, and 3D MOFs, has been discussed with sensing using these materials. Further, strategies to improve the sensing performance of these MOFs are discussed which will help future researchers in developing tailor-made devices for targeted analytes. At last, the paper concluded with the future research directions and the feasibility for developing next-generation, highly sensitive for real-world applications.