A novel approach to improving oxidizing-gas sensing ability of p-CuO nanowires using biased radial modulation of a hole-accumulation layer

Abstract

The attachment of n-TiO₂ nanoparticles (NPs) onto networked p-CuO nanowires (NWs) greatly improves the sensing abilities of the NWs for oxidizing gases. However, the attachment is harmful to the detection of reducing gases. In contrast to the case of pristine p-CuO NWs in which the hole-accumulation layer is equally modulated in the radial direction in NWs during adsorption and desorption of oxidizing and reducing gases, the attachment of n-TiO₂ NPs induces less modulation for reducing gases but more modulation for oxidizing gases. This is because a biased modulation of the hole-accumulation layer is established by the charge carrier transfer between NWs and NPs. The approach in this study provides an insight into designing p-type NW sensors for sensitive detection of oxidizing gases.