The advance of science and technology of sensors is of great importance for sustainable development of society, and some of the biggest problems are the manufacture of sensors with high performance at low operating temperatures and also reducing the cost of production. In this sense, this proposed research aims to study the effects of silver (Ag) and reduced graphene oxide (RGO) in composites with tungsten trioxide (WO3) for the detection of volatile organic compounds (VOCs) at room temperature in paper substrates. The Ag-WO3 composite will be obtained by photodeposition nanoparticles (NPs) of Ag in the WO3 surface previously prepared by ultrasonic spray synthesis method assisted by microwave (SUAM). Thus, the Ag NPs will work in electronic awareness of the WO3 surface due to a change in the oxidation state of Ag caused by redox reactions with VOCs. Already the RGO-WO3 type structures will be synthesized in a single step by SUAM method by reduction of graphite oxide (GO) to RGO. The function of RGO is to act as electron acceptor in the heterostructure, causing the change of the WO3 band gap to facilitate electronic conduction in the material. Thus, the benefits of Ag and RGO consist in increasing the adsorption process, sensitivity and reversibility of the sensor limits of detection, improving detection at room temperature. Both types of composites will be evaluated in the presence of different concentrations of VOCs (ex.: acetone, 2-butanone and toluene) by conductometric measurements. Therefore, the main challenges of the proposal are the synthesis of the materials by the new method SUAM; the production of sensors based on Ag-WO3 and RGO-WO3 deposited on the interdigital electrodes of graphite on paper, and finally, applying the VOCs detection at room temperature. Indeed, the studied materials may have potential for development of new sensors for noninvasive diagnosis of diseases correlated with VOC in breathing (eg .: diabetes, lung cancer and liver cancer). This proposal has the support of aid to regular research funded by FAPESP (14 / 17343-0).
News published in Agência FAPESP Newsletter about the scholarship: