Assembly of ZIF-67 Metal-Organic Framework over Tin Oxide Nanoparticles for Synergistic Chemiresistive CO Gas Sensing.

Metal-organic frameworks (MOFs) are widely known for their record storage capacities of small gas molecules (H , CO , and CH ). Assembly of such porous materials onto well-known chemiresistive gas sensing elements such as SnO could be an attractive prospect to achieve novel sensing properties as this affects the surface chemistry of SnO . Cobalt-imidazole based ZIF-67 MOF was grown onto preformed SnO nanoparticles to realize core-shell like architecture and explored for greenhouse gas CO sensing. CO sensing over SnO is a challenge because its interaction with SnO surface is minimal. The ZIF-67 coating over SnO improved the response of SnO up to 12-fold (for 50 % CO ). The SnO @ZIF-67 also showed a response of 16.5±2.1 % for 5000 ppm CO (threshold limit value (TLV)) at 205 °C, one of the best values reported for a SnO -based sensor. The observed novel CO sensing characteristics are assigned to electronic structure changes at the interface of ZIF-67 and SnO .