Near‐Zero Power MOF‐Based Sensors for NO2 Detection

Detection and capture of toxic nitrogen oxides (NOx) is important for emissions control of exhaust gases and general public health. The ability to directly electrically detect trace (0.5-5 ppm) NO(2)by a metal-organic framework (MOF)-74-based sensor at relatively low temperatures (50 degrees C) is demonstrated via changes in electrical properties of M-MOF-74, M = Co, Mg, Ni. The magnitude of the change is ordered Ni > Co > Mg and explained by each variant's NO(2)adsorption capacity and specific chemical interaction. Ni-MOF-74 provides the highest sensitivity to NO2; a 725x decrease in resistance at 5 ppm NO(2)and detection limit <0.5 ppm, levels relevant for industry and public health. Furthermore, the Ni-MOF-74-based sensor is selective to NO(2)over N-2, SO2, and air. Linking this fundamental research with future technologies, the high impedance of MOF-74 enables applications requiring a near-zero power sensor or dosimeter, with the active material drawing <15 pW for a macroscale device 35 mm(2)with 0.8 mg MOF-74. This represents a 10(4)-10(6)x decrease in power consumption compared to other MOF sensors and demonstrates the potential for MOFs as active components for long-lived, near-zero power chemical sensors in smart industrial systems and the internet of things.