A comparative DFT study on NO2 adsorption and sensing activities of pristine, reduced and Pr3+-doped CeO2 (110) surface

Surface site activation enhances the sensing properties of the CeO2 (110) surface. Herein, the adsorption of nitrogen dioxide (NO2) on pristine and modified CeO2 (110) surfaces has been studied in detail using quantum chemical calculation. The introduction of the single praseodymium atom on the CeO2 surface reduces its band gap from 1.93 to 0.53 eV, which in turn enhances the adsorption energy from -0.58 (pristine) to -1.34 eV (doped) and also prolongs the desorption time, indicating stronger adsorption ability. The density of states (DOS) and projected density of states (PDOS) analyses reveal that Pr doping modifies the electronic properties of the CeO2 (110) surface which improves NO2 sensitivity. Further, it is also observed that 0.57 eV increase in the work function for NO2 adsorption on Pr doped CeO2 surface, indicating stronger interaction compared to the pristine CeO2. In contrast, reduced CeO2 surfaces do not exhibit any significant change in sensing properties. Thus, it is understood that Pr-doped CeO2 (Pr/CeO2) surfaces exhibit better stability and sensitivity towards NO2 adsorption compared to pristine and reduced surfaces. Therefore, this study provides insight into the rational design of advanced gas sensing materials based on modified CeO2 (110) surfaces, contributing to the development of an efficient air quality monitoring system.