Synthesis, characterization and DFT studies of zinc-doped copper oxide nanocrystals for gas sensing applications

Abstract

Due to their unique properties, p-type copper oxide nanostructures have demonstrated promising potential for various applications, especially for the detection of ethanol vapour and other volatile organic compounds (VOCs). In this work a simple and cost-effective synthesis from chemical solutions (SCS) at low temperatures (≤80 °C) and rapid thermal annealing (RTA) process were used to grow zinc-doped copper oxide (Zn_xCu_1−xO_y) nanostructures. The structural, morphological, vibrational, chemical, electronic and sensorial characteristics of Zn_xCu_1−xO_y nanocrystallite layers obtained by using such an efficient approach based on both, the SCS and RTA processes, have been studied. The investigations demonstrated the possibility to tune sensitivity from VOC to H₂, as well as an improved response and high selectivity with respect to hydrogen gas for Zn_xCu_1−xO_y nano-crystalline thin films with x = 0.03. Density functional theory calculations showed that the charge transfer together with changes in the Fermi level facilitate H₂ gas sensing, which is further enhanced by Zn doping. Hydrogen gas sensing with a high response and selectivity using p-type hybrid semiconductor nanostructures has been reported. An improved stability in humid air was observed by exposure of doped samples to rapid thermal annealing process for the first time. The experimental and calculation results provide an alternative to sensitive and selective detection of ethanol and hydrogen gases, which would be of particular benefit in the area of public security, industrial and environmental applications.