Tunable macro-mesoporous ZnO nanostructures for highly sensitive ethanol and acetone gas sensors

Tunable macro-mesoporous ZnO (M/m-ZnO) nanostructures with a wurtzite hexagonal structure have been successfully synthesized using polymer colloids as a hard template and 20-40 nm ZnO nanoparticles as a precursor via controlling the ratios of colloids and ZnO nanoparticles. The as-prepared macro-mesoporous ZnO nanostructures are investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) techniques. Gas sensing performance is carried out for ethanol and acetone at different temperatures and concentrations. The gas sensing results show that the tunable M/m-ZnO nanostructures exhibit excellent gas sensing performances because the hierarchical macro-mesopores provide a large contacting surface area for electrons, oxygen and target gas molecules, offer smooth transport channels for target gas diffusion and finally enhance the gas molecular diffusion kinetics. The M/m-ZnO-600 nm demonstrates the best performance for ethanol and acetone detection. In addition, the sensor based on M/m-ZnO-600 nm gives obvious tendencious selectivity and a good repeatability and long-term stability to acetone at the optimum temperature of 300°C. This work suggests that the macro-mesoporous ZnO is a potential material for advanced gas sensing.