Ab-initio study of acetone sensing mechanism by photocatalytic WO3 and SnO2 chemiresistors

Sensitivity and selectivity are the two major parameters that should be optimised in chemiresistive devices with boosted performances towards Volatile Organic Compounds (VOCs). In many cases an excellent UV light responsivity with a high chemical sensitivity at RT is found [1-3]. Despite a plethora of metal oxides/VOCs combinations that have been investigated so far, a close inspection based on theoretical models to provide guidelines to enhance sensors features has been scarcely explored. In this work, we measured experimentally the sensor response of WO3- and SnO2-based chemiresistors towards acetone adsorption. In the latter case the role of a Zn-porphirine (ZnTPP) in the composite nanostructure is investigated. In order to shed light on these experimental results, we modelled both a defective γ−WO3 [4] and a SnO2 surfaces by means of ab initio density functional theory calculations [5]. Adsorption of acetone and ZnTPP has been also considered and the derived spectral properties in terms of ground state density of states (worked out within the LDA-1⁄2 approach) are reported.