Effect of platinum nanoparticles on the chemoresistive gas sensitive properties of the ZnO/Pt composite

Abstract

The ZnO/xPt nanocomposites (x = 0.5, 1, 2, 3 mol.%) obtained by the solvothermal method were used for microextrusion printing of films onto special Al2O3/Pt sensors. The obtained powders have a hexagonal crystal lattice and consist of zinc oxide flowers (152–185 nm) assembled from rods (53–78 nm), and platinum nanoparticles of 2–5 nm are on their surface. Using XPS, platinum was found to be partially in an oxidized state (as PtO and PtO2). Using impedance spectroscopy, the electrophysical characteristics of the samples were studied: temperature and frequency dependences of conductivity, which have linear and degree character, respectively. The chemoresistive gas-sensitive properties to CO, H2, C6H6, NO2, NH3, СH4, С3H6O and C2H5OH at 200–300 °C has been studied. The highest response was observed at 225 °C for ethanol. It was shown that by increasing platinum content from 0.5 to 3 mol.% Pt a significant increase in response (Rair/R) to 100 ppm ethanol from 17 to 47, but the process kinetics deteriorated. The detection mechanism of ethanol has been studied in detail, as well as the effect of humidity on the received signal. Using the principal component method, it is shown that the sensors can be used for the selective separation of a wide group of gases.