Acetylene gas sensing properties of an Ag-loaded hierarchical ZnO nanostructure-decorated reduced graphene oxide hybrid

• Ag NPs-loaded hierarchical ZnO nanostructure-reduced graphene oxide hybrid was synthesized by photochemical method.
• 5 wt% Ag-loaded hierarchical ZnO nanostructure-reduced graphene oxide hybrid enhanced the acetylene sensing performances.
• Two dimensional graphene acted as a support catalyst.
• The fabricated sensor showed good repeatability, fast response and very good selectivity.
• The sensor response characteristics and response/recovery times in terms of humidity interface were also investigated and explained in details.

Acetylene (C2H2) gas sensors were developed by synthesizing an Ag-loaded hierarchical (Hrc) ZnO nanostructure-reduced graphene oxide (Ag/ZnO Hrc-RGO) hybrid using a facile and rapid photochemical method. Morphological characterizations showed the formation of well-dispersed Ag nanoparticles-loaded hierarchical ZnO nanostructures onto the 3- to 5-layer thick RGO sheets. The hierarchical ZnO nanostructures were composed of numerous randomly oriented porous ZnO nanosheets with an average sheet thickness of 6 nm. It was also observed that Ag nanoparticles with an average diameter of 40 nm were closely affixed onto the ZnO nanosheets. Structural analysis revealed good agreement with the standard crystalline phases of ZnO, Ag and RGO. Gas-sensing characteristics of the synthesized materials were carried out in a temperature range of 25–300 °C at different C2H2 gas concentrations. At 200 °C, 5 wt% Ag/ZnO Hrc-RGO hybrid showed a preferable detection of C2H2 with high sensor response (12.3 toward 100 ppm), fast response time (57 s), a limit of detection (LOD) of 3 ppm, good linearity, with excellent reproducibility and selectivity. The fabricated sensor also showed less humidity effect in an open air environment.