Au nanoparticles decorated ZnS hollow spheres for highly improved gas sensor performances

Novel Au nanoparticles decorated wurtzite ZnS hollow spheres (Au NPs-ZnS HSs) were successfully synthesized by simple hydrothermal and deposition-precipitation methods without using any surfactants or toxic organic solvents. The fabribated Au NPs-ZnS HSs based gas sensor showed high responses, quick response/recovery characteristics, excellent reproducibility and simultaneously highly improved responses compared with the pristine ZnS HSs based sensor to several volatile organic pollutants (VOPs) such as ethanol, n-propanol and n-butanol at a low operating temperature of 260 °C. In terms of other VOPs, the sensor also displayed a high response to acetone (84.4%) and formaldehyde (75.8%), and a certain response to toluene (46.9%) and benzene (37.8%), indicating its multifunctional gas sensor application. The superior gas sensor performances could be attributed to the catalytic and spillover effect of Au NPs and the unique rough, porous and hollow structure which can improve the accessible surface area of the gas sensing materials, form conjugated electron depletion layers on both the outer and inner surfaces and facilitate the diffusion and transport of the tested gases. The as-synthesized Au NPs-ZnS HSs are considered to be one of the extremely promising candidate materials in gas sensor applications, and are also expected to provide other potential applications in the future.