Density Functional Theory Investigation of Pristine and Ni-Doped CeO2 (110) for C2H4 Detection Based on Optimized Work Functions

With the rapid development of global industrialization, industrial production leads to the emission of large quantities of toxic gases and long-term exposure of these gases to the air poses a serious threat to human health and the ecological environment. Therefore, online monitoring of toxic gases is a worthy task. In this work, the structures of pristine cerium oxide (CeO2) and nickel-doped cerium oxide (Ni-CeO2) surfaces are established based on the first-principles, and 12 adsorption structures of NH3, CH4, SO2, H2S, CO, C2H4 and gas molecules on the pristine CeO2 and Ni-CeO2 surfaces are constructed by geometrical optimization. We investigate the adsorption performance and gas-sensing mechanism of each adsorption system from various aspects, such as adsorption energy, band gap, electron density, density of states, frontier molecular orbital theory, conductivity, sensitivity, recovery time, and work function. The results showed that Ni-CeO2 significantly improved the adsorption properties of C2H4 (−1.784 eV), H2S (−1.036 eV), SO2 (−1.731 eV), and NH3 (−1.045 eV). The Ni-CeO2/C2H4 system exhibits high response (116.414), high work function (4.45 eV), and fast recovery (74.24 s) as well as strong resistivity changes. Hence, the theoretical simulation experiments in this paper provide theoretical guidance for the development of a highly sensitive, work function type (Ni-CeO2) gas sensor for the detection of the harmful gas C2H4 in the atmosphere.