Enhanced response to NO2 with CuO/ZnO laminated heterostructured configuration

Abstract The charge separation behavior is easily ignored in the field of gas sensor. In this work, a novel perspective focuses on the charge separation theory for the exploration of the gas sensing mechanism. For this target, the novel laminated CuO/ZnO p–n heterostructured systems are introduced to achieve this attempt. The desired system is composed of the parallel Au electrodes, CuO and ZnO functional layers. It is worth noting that the synergistic effect of the laminated heterostructure and external electric field can strengthen the unidirectional charge separation in both CuO and ZnO layers. Comparing with the plain CuO, the optimal response is enhanced 3.58 times by utilizing the [electrode/CuO/ZnO] heterostructured configuration at 350 °C. Interestingly, we observe that the resistance changed remarkably once the NO 2 gas is cut off, and its detailed formation mechanism is discussed. We believe that the transformation process from double electrons to single electron is responsible for the abnormal results. The analysis method for gas sensing mechanism has a certain guiding significant for the design of gas sensor with high performance by using the laminated heterostructured configuration.