Synthesis of unique ZnO/SnO2 core–shell structural microspheres and their gas-sensing properties

Nanomaterials with unusual architectures or morphologies often exhibit novel functional properties. Here, we apply a simple two-step solution method to synthesize the ZnO/SnO2 microspheres with an average size of 1–2 μm, which exhibit a unique core–shell architecture with a uniform dispersion of SnO2 nanoparticles on surfaces of spherical ZnO cores. We further investigate in detail the morphology evolution with reaction time, based upon which a likely growth mechanism is proposed. In property, the prepared core–shell structural ZnO/SnO2 microspheres show excellent gas-sensing functions to ethanol gas of 50 ppm at an optimal temperature as low as 250 °C, rendering the hybrid microspheres a promising gas-sensing material for the on-site detection of ethanol.

► A simple method was used to synthesize the ZnO/SnO2 microspheres.
► The microspheres show a unique core–shell architecture.
► Gas-sensing functions are enhanced greatly due to the unique structures.
► The hybrid microspheres are promising for on-site detection of ethanol.