Highly sensitive and room temperature detection of ultra-low concentrations of O3 using self-powered sensing elements of Cu2O nanocubes

Abstract

The fundamental development of the design of novel self-powered ozone sensing elements, operating at room temperature, based on p-type metal oxides paves the way to a new class of low cost, highly promising gas sensing devices. In this work, p-type Cu₂O nanocubes were synthesized by a simple solution-based method and tested as a self-powered ozone sensing element, at room temperature (25 °C) for the first time. Highly crystalline Cu₂O nanocubes with 30 nm size were characterized by X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM). Self-powered sensing elements of Cu₂O nanocubes have been successfully fabricated by deposition of Cu₂O nanocubes on interdigitated electrodes (IDEs) consisting of two connection tracks with 500 digits and a gap of 5 μm in order to investigate their response to ozone at room temperature. The experimental results showed that the use of nanocubes as sensing elements was suitable for detecting ultra-low concentrations of O₃ down to 10 ppb at room temperature with very high sensitivity (28%) and a very low response/recovery time. The reversible sensing process of the relatively weak binding of O₃ species by trapping sites on Cu₂O facets with increased oxygen content was studied by using density functional theory (DFT) calculations.