Two-step growth of core-shell TiO2/SnO2 nanorod arrays on FTO and its application in gas sensor

The development of gas sensors based on metal oxide semiconductor (MOS) with highly regular morphology, highly stable structures, and easy preparation is greatly desired but remains a challenge. Herein, we first prepared a highly regular array of TiO2 nanorods on FTO by a modified in situ hydrothermal method. Then a uniform SnO2 layer grew on the nanorods to form a core-shell nanocomposite by an ion-layer adsorption-reaction process. The TiO2/SnO2 sensors show enhanced gas sensing performance compared with the TiO2 sensors, including higher sensitivity to ethanol, lower working temperature, and better long-term stability. And the highest ethanol response can be obtained when the growth cycle of the SnO2 shell was two times. The gas-sensing mechanism of the TiO2/SnO2 nanocomposites was discussed concerning the unique core-shell structure and a heterojunction between TiO2 and SnO2.