Adsorption and gas sensitive behavior of Co2+ doped TiO2(101) crystal planes

Abstract

Density functional theory (DFT) and Electrochemical Impedance Spectroscopy (EIS) were used to study the molecular adsorption behavior of the Co2+ doped TiO2(101) crystal plane, and the ethanol molecular gas sensitivity test was performed. Theoretical models indicate that doping leads to oxygen defects on the crystal plane and further chemisorption of two oxygen molecules, resulting in reduced electrical conductivity and improved oxygen storage capacity on the crystal plane. Ethanol molecules do not compete with N2, O2, and H2O molecules on doped crystal planes because of their different adsorption active sites, which means that the response time of gas-sensitive detection of ethanol molecules is short and is not interfered with the air molecules in the test environment. These results were confirmed by EIS and gas sensitivity experiments. The change of electrical conductivity after the adsorption of molecules on the crystal plane was confirmed by EIS. The enhanced oxygen storage capacity of the doped crystal plane was confirmed by the expansion of the linear response range of gas-sensitive detection from 20-100 ppm before doping to 20–1200 ppm. This provides a scientific basis for effectively shortening the gas-sensitive response time, increasing the concentration range, improving the oxygen-carrying capacity, and enhancing the catalytic and gas-sensitive properties of the material.