Au-functionalized porous ZnO microsheets and their enhanced gas sensing properties

A novel and facile strategy was applied to synthesize Au nanoparticles (Au NPs)-functionalized ZnO microsheet (MS) hybrid-materials. First, the layered 2D porous ZnO MSs were fabricated by a simple hydrothermal method followed by a calcination process, only using zinc acetate dihydrate and urea as the sources. Then the as-prepared ZnO MSs were further functionalized by small Au NPs, assembled by using green, non-toxic lysine as a capping agent. The obtained samples were characterized by means of XRD, TGA, SEM, TEM and EDS. In order to prove the enhanced combining properties of the hybrid materials, gas sensors were fabricated based on them. And the obtained results showed that, after functionalization with Au NPs, the porous ZnO MS hybrid sensor exhibited enhanced sensing performances towards several volatile organic compounds (VOCs) including n -butanol, ethanol, methanol, acetone and benzene, indicating its potential application as a gas sensor in detecting VOCs. The enhanced sensing properties are related to the unique structure of porous ZnO MSs and the strong spillover effect of small Au NPs for catalyzing sensing reactions, as well as the increased Schottky barriers caused by the electronic interaction between Au NPs and the ZnO support. The relationship between the enhanced VOC sensing properties and the interaction of Au NPs with the porous ZnO support for the Au NPs-ZnO hybrid sensor was discussed.