Tailoring the surface chemistry of ZnO nanowires via mixed self-assembly of organosilanes for selective acetone detection

We are proposing a novel active sensing surface based on mixed-SAMs (APTES and TEOS) functionalized ZnO nanowires (NWs) for selective detection of acetone. We showed that mixed-SAMs are a superior strategy for sensing performance enhancement not only from bare ZnO NWs but also from homogenous SAM provided suitable mixing ratios were selected. The mixed-SAMs functionalized NWs exhibit high selectivity toward acetone with a response value of 256 ± 36 (50 ppm) due to the molecular interaction between the acetone C═O group and terminal—CH3 and —NH2 groups of SAMs. Indeed, for the very first time, the effect of the mixing ratio on the sensing performance was systematically discussed in this work which is one of the most important aspects of the mixed-SAM approach. In particular, two main factors i.e., the variation in the charge distribution of mixed-monolayer and the modification in the molecular interactions between terminal SAMs groups acetone carbonyl group caused by mixing ratio plays the key role. Functionalized sensors exhibit high stability for the period of 2-months with lowest detection limit of 0.05 ppm, makes them a potential candidate for acetone exhaled breath analysis.