Effect of Gold Addition on the Sensitivity of Single-Electrode Gas Sensors Based on (In, Ga)2O3 to Carbon Monoxide and Methane

The structural and phase features of the (In,Ga)2O3 solid solution obtained by the sol-gel method were studied using X-ray powder diffraction, IR spectroscopy, and scanning electron microscopy. Single-electrode gas sensors were fabricated, and their sensitivity to gas mixtures containing methane and carbon monoxide was investigated. It was shown that impregnating the sensor with a gold-containing solution leads to a significant increase (by approximately 3–4 times) in the sensor’s sensitivity to carbon monoxide and a slight decrease in its sensitivity to methane. The developed sensors enable the detection of low carbon monoxide concentrations (<1 vol %) with a short response time (~120 s) and recovery time (~5 s). The nature of the sensitivity dependence on CO concentration was established, and an explanation for the observed effects was proposed.