Effect of metal catalysts or reduced graphene oxide on metal oxides semiconductors for detection of volatile organic compounds

Abstract

The research project concerns the evaluation of the use of metal catalysts (MCat) or reduced graphene oxide (RGO) in metal oxide semiconductor (MOS) in the composites MOS-MCat and MOS-RGO, respectively, to improve the sensitivity, selectivity and response time of the volatile organic compounds (VOCs) sensors. The MOS-MCat structures are obtained by deposition of MCats (e.g. Pt, Pd and Ag) by direct ion exchange between the ligands of the MCat complex with hydroxyl surface of the MOS (e.g. SnO2, WO3, CuO and NiO) previously prepared by microwave-assisted hydrothermal method. Instead, MOS-RGO composites are synthesized in one step from the dispersion containing a precursor solution of the metal salts of the MOS, chemical basis and graphene oxide by microwave-assisted crystallization. It is expected that the MCats promote electronic sensitization (Fermi level control) and chemical sensitization (enrichment of the surface with reactive species by catalysis) to prevent low selectivity, slow response and disabling the sensor. On the other hand, the RGO act as electron acceptor to facilitate interaction between OMSs VOCs and chemical interactions via pi-pi type, in addition to increasing the surface area of the composite. The main benefits of RGO consist in increasing the adsorption, sensitivity, reversibility and detection limits of the sensor process. Both types of composites will be evaluated in the presence of different VOCs (e.g. acetone, ammonia, ethanol and toluene) by conductometric measurements. The originality of the proposal is that to understand the relationship between the effects of MCat nanoparticles and RGO in the interface with the OMSs will be more sensitive devices, selective and faster response times compared to those described in the literature. As a challenge, the composite shall be tested in similar conditions of high human breathing (relative humidity between 90 to 95%). Indeed, the materials studied may have potential to diagnose diseases such as diabetes and lung cancer. Allied to scientific development, we seek the training of human resources at the undergraduate and graduate students with the nucleation of a new research group in the Department of Chemistry and Environmental Sciences UNESP, campus of SJ do Rio Preto. (AU)