Methyl (-CH3)-terminated ZnO nanowires for selective acetone detection: A novel approach toward sensing performance enhancement via self-assembled monolayer

The inspiration behind this work is to show the importance of tailoring metal oxide (MOX) nanowires with suitable self-assembled monolayers (SAMs) for the development of highly efficient, selective, and low power consuming chemical sensors. We showed that the methyl (-CH3) terminated-ZnO nanowires exhibit improved sensing performance toward acetone at 250 °C. The origin of enhancement in the sensor response is found to be the intermolecular interactions between SAM methyl (-CH3) and acetone carbonyl (CO) groups, while weak methyl-methyl interactions between the SAM and acetone molecules participate in enhancing sensor selectivity. Not only the response, but the ability of the sensor to discriminate acetone molecules is also improved after functionalization. Indeed, the functionalized sensor exhibits a detectable response even with shorter exposure times. Moreover, as compared to the literature concerning different sensor structures (no report is available on tetraethyl orthosilicate (TEOS) functionalized MOX nanowire based chemical sensors), TEOS functionalized sensors exhibit superior performance at relatively lower operating temperatures. Consequently, in contrast to other nanowire modification strategies such as metal-particle decorated MOX nanowires, the SAM functionalization strategy has the greatest potential to develop future high performance chemical sensor devices not only for acetone but also for other important analytes such as environmental pollutants.