The development of CuO-ZnO based heterojunction for detection of NO2 gas at room temperature

The goal of the current research was to develop CuO-ZnO heterojunction capable of detecting NO2 gas at room temperature. Pure CuO and CuO-ZnO composite samples were developed by changing the weight percentage of CuO and ZnO using a simple precipitation method and nominated as CZ0, CZ1, CZ2 and CZ3. Structural, optical and morphological properties of pristine CuO and heterojunctions were studied using XRD, FE-SEM, BET, XPS, FTIR and PL. Investigation of gas sensing properties revealed that the CZ2 sample (20 wt% ZnO) exhibited maximum response of 36.7% to 100 ppm of NO2 gas at room temperature. The mechanism behind the response of pristine material and CuO-ZnO was explained in detail. The development of p-n heterojunction due to the combination of p-type CuO and n-type ZnO was responsible for the increase in the gas detecting capabilities of the synthesized composite material for detecting NO2 gas at ambient temperature. Hence, the proposed approach focuses on the design of a cost-effective and sensitive gas sensor that can sense NO2 gas even at room temperature.