Heterojunctions on Ta<sub>2</sub>O<sub>5</sub>@MWCNT for Ultrasensitive Ethanol Sensing at Room Temperature
Wenyi Shao, Jianguo Lü, Zicheng Zheng, Rumin Liu, Xinchang Wang, Zhenyun Zhao, Yangdan Lu, Liping Zhu, Zhizhen Ye
Abstract
Heterojunctions of Ta 2 O 5 and multiwalled carbon nanotubes (MWCNTs) have been successfully synthesized by a facile and cost-effective hydrothermal method, with a super thin and uniform Ta 2 O 5 shell wrapped around the MWCNT. The combination of Ta 2 O 5 and MWCNTs at the interface not only modifies the morphology but also forms the p–n heterojunction, which contributes to the reconstruction of band structure, as well as the low resistance of matrix and highly chemisorbed oxygen content. The Ta 2 O 5 @MWCNT p–n heterojunction exhibits ultrasensitive performance to ethanol at room temperature, with a response of 3.15 toward 0.8 ppm ethanol and a detection limit of 0.173 ppm. The sensor has a high reproducibility at various concentrations of ethanol, superior selectivity to other gases, and long-term stability. The strategy of hybriding metal oxide semiconductors with MWCNT promises to provide a feasible and further developable pathway for high-performance room-temperature gas sensors.