LSPR effect enabled Ag-TiO2 nanotube arrays for high sensitivity and selectivity detection of acetone under visible light

Local surface plasmon resonance (LSPR) effect induced by noble metal is an effective strategy to improve gas sensing performance, and has aroused widespread research interest. However, the mechanism by which LSPR improving gas sensing characteristics is still not very clear. For instance, why the hot electrons generated by the LSPR effect and the photo generated charge carriers generated by semiconductor illumination have different effects on gas sensing characteristics. This study develops a light assisted gas sensor based on Ag-TiO2 nanotube arrays (Ag-TiO2 NTA). Through a series of experimental demonstration, the different effects of photo generated carriers and hot electrons on gas sensing properties have been explained from a physical perspective. Meanwhile, it has found that the lifetime of electrons excited to the conduction band exhibits a significant impact on gas sensing performance. The Ag-TiO2 NTA with a photoreduction time of 1 hour (Ag1 h-TiO2 NTA) presents excellent acetone sensing performance (S = 66.4), which is 7 times higher than that of the pure TiO2 NTA towards 100 ppm acetone under 405 nm light illumination. In addition, the sensors exhibit fast response time (tres= 1 s), robust antihumidity ability (10-90 % RH), and low detection limit (296.8 ppb). This work provides new strategies for developing of photo assisted gas sensors.