UV-activated hollow ZnO@TiO2 heterostructured nanaospheres for detecting formaldehyde at room temperature

The hollow ZnO @ TiO 2 heterostructured nanospheres were synthesized by hydrothermal method using carbon nanospheres as sacrificed templates. With UV activation, the response of ZnO @ TiO 2 based chemiresistive-type sensors to 10 ppm formaldehyde is 11.02 at room temperature which is 5.48 times larger than that of the pure hollow ZnO. The response and recovery time significantly reduced to 14 s and 16 s. Selectivity, stability and repeatability of the hollow ZnO @ TiO 2 based sensor under UV-activation have also been examined. The sensing mechanism of the sensor to formaldehyde have been investigated by AC impedance spectroscopy , in-situ DRIFTS , and DFT theoretical calculation.