CuO/TiO2 heterostructure-based sensors for conductometric NO2 and N2O gas detection at room temperature

Abstract

Nitrous oxide (N2O) is hazardous gas extensively used in surgeries as an anesthetic and released into the atmosphere without any treatment. Despite low concentrations in the atmosphere, it has for 300 times larger warming coefficient to the greenhouse effect than CO2. There are only a few studies dedicated to the development of N2O gas sensors, but not for room temperature (RT) and ultra-low concentrations. In this study, we developed an ultrasensitive gas-sensing device operating at RT based on CuO/TiO2 heterojunctioned nanointerfaces prepared by scalable reactive magnetron sputtering technique with glancing angle deposition. The CuO/TiO2 heterojunctioned nanointerfaces demonstrated N2O gas sensitivity for ∼2 times higher than TiO2 mono-layer, and the device exhibits an outstanding detection limit of 50 ppb at RT, quick response and recovery times (∼36 s and ∼50 s). The ultrasensitivity of gas sensor is achieved by providing control over nanoarchitecture and comparable size of the nanorods-like structure to the doubled Debye lengths (∼70–80 nm). The applied nanoarchitecture design opens a flexible platform for different gas sensing devices where the array of p-n heterojunction nanorods was utilized efficiently and with technological simplicity. The statistical analysis of variances shows that obtained data is more confident and reproducible.