Core/Shell of p-CuxO/n-ZnO Nanowire Arrays for H2S Gas Sensor

Abstract

The p-CuxO core/n-ZnO shell heterostructure nanowire (NW) arrays were fabricated by thermal decomposition. Based upon the core/shell nanowire-based all oxide p-n junctions. The samples were analyzed by XRD, SEM, EDS and TEM. X-ray diffraction (XRD) analysis showed that the p-CuxO core/n-ZnO shell NW consisted of phase of p-CuxO and wurtzite phase of n-ZnO. The morphology analysis showed average diameter and length of nanowires of ̴ 50 to 200 nm and ̴ 10 to 30 µm, respectively. The EDS spectrum confirmed the presence of required elements in the p-CuxO core /n-ZnO shell NWs. It was found that Zn, O and Cu are distributed over the wire areas according to a ratio of 1:2 by atomic% ratio of Cu:Zn to get good core/shell structure. The TEM characterizations showed that the n-ZnO shell nanoparticles were comprised of n-ZnO polycrystalline nanoparticles (NPs) on the surface of p-Cu2O core NWs. The H2S gas sensing properties of the p-CuxO/n-ZnO NWs were evaluated in air containing dilute H2S gas at sensing temperatures (T) of 350°C. The response of 20.6 for p-CuxO/n-ZnO NW sensor to H2S gas was enhanced compared to that of the n-ZnO NW. The enhanced response of p-CuxO/n-ZnO NW sensor is due to increasing surface area, the increased amount of chemisorbed oxygen species on NP surface and the increased conductivity.