Study on gas sensitive behavior of SnO2(221) and (110) crystal planes

The gas-sensitive behavior of (221) and (110) crystal planes of SnO2 to ethanol molecules were studied in this paper. The gas-sensitive detection results to 100 ppm ethanol showed that the response time of the (221) crystal plane is better than the (110) plane, which is 8 s and 62 s, respectively. The theoretical simulation shows that the gas-sensitive response time is determined by the adsorption speed of O2 on the crystal plane. In the detection process of ethanol molecules, the O2 molecules adsorbed on the crystal plane will be gradually consumed, causing the change of electrical conductivity on the crystal plane, to complete the gas sensitivity detection. In the air, N2, O2, and H2O molecules occupy the same active sites on the (110) crystal plane, and adsorption competition leads to the increased response time of gas-sensitive detection. However, the three molecules occupy different adsorption active sites on the (221) crystal plane, so the adsorption time of the O2 molecule is shorter. Understanding the adsorption behavior of molecules on crystal planes is of great significance to the selection of gas-sensitive materials and the optimization of gas-sensitive properties. •The adsorption speed of O2 determines the detection time of ethanol molecules.•The adsorption speed of O2 depends on whether there is competitive adsorption.•Molecules occupy the same active site resulting in competitive adsorption.•O2 and N2 occupy the same active site on the SnO2 110 plane, but not on the 221 plane.