Effect of Au nanoparticles on the gas sensitivity of nanosized SnO2

Abstract

The effect of the nanosized gold state on the adsorption-sensitive properties of tin dioxide under the detection of СО, СН4 and С2Н5ОН vapours has been studied. Different techniques that allow obtaining gold particles with the average size ranging from 1.9 ± 0.1 nm to 3.5 ± 0.5 nm were applied. The structural features and the surface state of SnO2 and SnO2–Au materials have been studied by using SEM, TEM, XPS, FTIR and UV–Vis spectroscopy. It has been found that an increase in the sensor response to СО, СН4 and С2Н5ОН vapours is achieved by adding gold in the form of colloid particles with the size range of 1.9–3.5 nm to SnO2·nH2O sol. The SnO2–Au layers with the larger particles (3.5 nm) demonstrate the highest response to С2Н5ОН while SnO2–Au (1.9 nm) composite is the most sensitive to CO and СН4. It has been shown that a selective detection of СН4 and СО in gas mixtures is possible by adjusting the voltage to be applied to SnO2–Au (1.9 nm) sensor. The enhanced sensitivity of the sensor to methane is caused by the nanosized state of both SnO2 and Au components as well as by the modifying effect of sulphur-containing stabilizer of Au particles.