Rh-Doped ZnO Monolayer as a Potential Gas Sensor for Air Decomposed Species in a Ring Main Unit: A First-Principles Study.

Using the first-principles theory, this paper studies the Rh-doping behavior on the ZnO monolayer and investigates the adsorption and sensing behaviors of a Rh-doped ZnO (Rh-ZnO) monolayer to NO2 and O3 to explore its potential as a gas sensor to evaluate the operation status of the ring main unit in the power system. The results indicate that the Rh dopant can be stably anchored on the TO site of the ZnO monolayer with an E b of -2.11 eV. The Rh-ZnO monolayer shows chemisorption of NO2 and O3, with E ad values of -2.11 and -1.35 eV, respectively. Then, the electronic behavior of the Rh-ZnO monolayer before and after gas adsorption is analyzed in detail to uncover the sensing mechanism for gas detection. Our findings indicate that the Rh-ZnO monolayer is a promising resistance-type gas sensor with a higher response to O3 and can be explored as a field-effect gas sensor with a higher response to NO2. Our theoretical calculations provide the basic sensing mechanism of the Rh-ZnO monolayer for gas detection and would be meaningful to explore novel sensing materials for gas detection in the field of electrical engineering.