Preparation and gas-sensing performance under photoactivation of TiO2 nanotubes/carbon nanotubes/ZnS quantum dots gas-sensitive materials

Abstract

This study reports the successful synthesis of TiO2 nanotubes (NTs)/carbon nanotubes(CNTs)/ZnS quantum dots(QDs) composites through a two-step hydrothermal method, followed by different characterization. For real application, the gas sensing performance of sensors based on these composites was evaluated under UV light activation at 100 °C. Results of characterization revealed that the composite exhibited a smooth surface and a well-defined p-n heterojunction structure Under UV light activation, the resistance of the composites first decreased linearly and then reached a stable state, whereas an increase in the gas flow rate of ethanol resulted in an elevated resistance. Notably, the sensor constructed by TiO2 NTs/0.1% CNTs/1% ZnS QDs (t + 0.1%c + 1%z) demonstrated the highest sensitivity at 100 °C when compared with TiO2 nanotube sensor operated at 250 °C, which highlight the feasibility of achieving low-temperature sensor through UV light activation. Furthermore, UV light irradiation improved the stability and gas selectivity of the composites. The composites exhibited higher sensitivity to ethanol than methane, making it suitable for ethanol gas sensing. Impressively, the TiO2 NTs/0.1% CNTs/1% ZnS QDs (t + 0.1%c+1%z) composite exhibited excellent long-term stability after continuous exposure to 10 ppm ethanol gas for 20 days.