Optical and gas sensing properties of mesoporous hollow ZnO microspheres fabricated via a solvothermal method

Mesoporous, hollow ZnO microspheres were synthesized via a hydrothermal method, using glycerol and zinc acetate as the starting materials. XRD and FESEM analysis showed that the surface morphology of the spheres with a Wurtzite structure could be reasonably adjusted by varying the weight ratio (Rw) of Zn(CH3COO)2 2H2O:H2O:C3H8O3. The responses of the gas sensor based on the spheres to 100 ppm ethanol and 100 ppm acetone are 18.9 and 10.4, respectively. The response and recovery times of the sensor to ethanol and acetone are 2 s and 3 s, 3 s and 5 s, respectively. The hollow spheres show an intense UV emission at 392 nm and a broad blue-green emission at 488 nm. Interestingly, a light trapping phenomenon is revealed by UV emission and scattering measurements on the microspheres, which can be attributed to the mesoporous shell and hollow structure of the microsphere.