Nanostructured SnO2 Microsphere-Based Gas Sensor Array Enhanced by Molecular Imprinting for Methanol and Ethanol Discriminative Detection

A modification approach is developed based on the idea of molecular imprinting technique to enhance the selective gas sensing performance of nanostructured SnO2 as gas sensors. The modification procedure, conducted on SnO2 microspheres as the porous substrate, involves in situ polymerization and calcination processes. A methanol-templated molecularly imprinted sample (cM-SnO2 MIP) was successfully synthesized via the modification procedure, which demonstrated great difference with its nonmodified counterpart (c-SnO2 MSs) in terms of both surface morphology and internal architecture. Gas sensing performance, including target gas response, selectivity, and dynamic sensing behavior, was investigated to validate the effectiveness of the imprinted cavities for methanol within cM-SnO2 MIPs. Compared to c-SnO2 MSs, the cM-SnO2 MIPs exhibited greatly enhanced methanol sensing selectivity and improved anti-interference ability by up to 2–10 times depending on the types of interference gases. Moreover, the predesigned target gas recognition capability of the molecularly imprinted sensors was proved by changing the template to ethanol and thus obtaining cE-SnO2 MIPs with excellent ethanol sensing selectivity as well as improved anti-interference ability. By constructing a sensor array, the excellent sensing selectivity of these nanostructured SnO2 microspheres was exploited to distinguish the chemically similar molecules, methanol and ethanol.