Enhanced NO Gas Sensing Properties Based on Rb-Doped ZnO/InO Heterojunctions at Room Temperature: A Combined DFT and Experimental Study.

In this work, alkali metal Rb-loaded ZnO/InO heterojunctions were synthesized using a combination of hydrothermal and impregnation methods. The morphology and structure of the synthesized samples were characterized by X-ray diffraction, field emission scanning electron microscopy, and transmission electron microscopy. The enhancement mechanism of the nitrogen dioxide gas sensing performance of the Rb-loaded ZnO/InO heterojunctions was systematically investigated at room temperature using density-functional theory calculations and experimental validation. The experimental tests showed that the Rb-loaded ZnO/InO sensor achieved an excellent response value of 24.2 for 1 ppm NO, with response and recovery times of 55 and 21 s, respectively. This result is 20 times higher than that of pure ZnO sensors and two times higher than that of ZnO/InO sensors, indicating that the Rb-loaded ZnO/InO sensor has a more pronounced enhancement in performance for NO. This study not only revealed the mechanism by which Rb loading affects the electronic structure and gas molecule adsorption behavior on the surface of ZnO/InO heterojunctions but also provides theoretical guidance and technical support for the development of high-performance room-temperature NO sensors.