Synthesis and characterization of Cu-doped ZnO/RGO nanocomposites for room-temperature H2S gas sensor

Abstract

Abstract The development of low or room temperature gas sensors having a response towards a particular target gas becomes a fascinating research topic for low power consumption applications. In this paper, a sensitive room-temperature hydrogen sulfide (H2S) gas sensors based on hydrothermally synthesized undoped zinc oxide (ZnO) and Cu-doped ZnO (CZO) nanostructures decorated with reduced graphene oxide (RGO) are successfully demonstrated. A simple air-spray deposition is employed as an effective method for uniform GO decoration on CZO nanostructured film which is further chemically reduced to form RGO. The influence of Cu-doping on crystallinity, surface-morphological, and chemical compositional properties of the material have been systematically investigated. The gas sensing properties of the synthesized nanocomposite sensors have been studied towards H2S at room temperatures (∼24 °C). Compared with undoped ZnO/RGO, 3CZO/RGO nanocomposite sensor exhibited a better response towards H2S. The sensor response increases almost linearly with the increase in H2S gas concentration and exhibits the evident response of 0.87%–100 ppm H2S at 24 °C with the response and recovery time of 14 and 32 s, and a theoretical limit of detection of about 136 ppb. The enhancement was accredited to the collegial effect of both Cu dopant and RGO. The sensor also shows good selective behavior towards H2S against H2. The H2S sensing mechanism associated with the p-type behavior of the 3CZO/RGO sensor is also discussed at length.