Core-shell TiO2/ZnO nanorod array films on FTO: Two-step synthesis and improved ethanol sensing performance

In this work, highly regular TiO2 nanorod array films were synthesized in situ on FTO by a facile hydrothermal method, and then ZnO shell layers were grown on the surface of the nanorods to form a core-shell structure via an ion-layer adsorption-reaction way. Compared to the TiO2 nanorods, the prepared TiO2/ZnO nanocomposites exhibited enhanced ethanol sensing performances, including a low working temperature, higher sensitivity, and faster response capability. The optimum sensor based on 2c-TiO2/ZnO exhibited the maximum response value of 30.85 toward 50 × 10−6 C2H5OH at 340 °C, which was almost 4.15 times higher than that of the TiO2 sensor. The improved ethanol sensing mechanism was discussed in relation to the unique nanorod array structure and the heterojunctions between TiO2 and ZnO. [Display omitted] •Core-shell TiO2/ZnO nanorod array films were prepared via a facile two-step method.•The TiO2/ZnO exhibited better ethanol sensing properties compared with pristine TiO2.•The enhanced ethanol sensitivity mechanism of TiO2/ZnO was discussed detailed.