Bimetallic MOFs-Derived Metal Oxides CoO/SnO Microspheres for Ultrahigh Response -Butanol Gas Sensors

The construction of p-n heterojunctions is expected to be one of the effective means to improve gas sensitivity. In this research, p-n heterojunctions are successfully constructed by metal oxides derived from metal-organic frameworks (MOFs). MOFs-derived bimetallic CoO/SnO microspheres are prepared by precipitation. Gas-sensing performance shows that the CoO/SnO sensor exhibits an extremely high response (/ = 641) to 20 ppm of -butanol at 200 °C, which is 19 times that of pristine SnO. It can detect -butanol gas at low concentrations, has good selectivity to alcohol gas, and reduces the interference of benzene gas. The improved gas sensitivity can be attributed to the formation of a stable heterojunction between CoO and SnO, resulting in a greater resistance change of CoO/SnO. CoO/SnO inherits the characteristic of high specific surface area of MOFs, which provides abundant sites for the reaction of the target gas and oxygen molecules. Finally, the gas-sensing mechanism of the CoO/SnO-based sensor is discussed in detail.