High response to H2S gas with facile synthesized hierarchical ZnO microstructures

• Hierarchical ZnO microstructures were synthesized using a facile solution route.
• A possible nucleation-growth mechanism was developed and carefully discussed.
• The morphology-dependent gas-sensing properties were systematically studied.
• Gas-sensing mechanism was investigated to explain the performance differences.

Three different hierarchical ZnO microstructures with high uniformity were synthesized and developed as H2S gas sensors. High response to H2S gas as low as 50 ppb was obtained by those microstructures. Particularly, the sphere-like microstructure exhibited extremely high response at the working temperature (220 °C). A possible nucleation-growth mechanism was proposed and the structures were carefully investigated. Our studies implied that the morphologies of micro/nanostructures could strongly affect the sensing performance, and hence, the effective design of gas sensors with semiconducting metal oxides could be realized.