Tao Xu,Yun Wang,Xiaofang Zhou,Xiaoli Zheng,Qun Xu,Zhimin Chen,Yumei Ren,Bo Yan
The recombination of photo-induced charges is one of the main issues to limit the large-scale applications in photocatalysis and photoelectrocatalysis. To improve the charge separation, we fabricate a novel type II 2D ultrathin TiO 2 /WO 3 ·H 2 O heterostructures with the assistance of supercritical CO 2 (SC CO 2 ) in this work. The as-fabricated heterostructures possess high photocatalytic activity for the degradation of methyl orange(MO) and high photocurrent response under simulated solar light (AM 1.5). For the TiO 2 /WO 3 ·H 2 O heterostructures, the MO solution could be degraded by 95.5% in 150 min, and the photocurrent density reaches to 6.5 μA cm −2 , exhibiting a significant enhancement compared with pure TiO 2 and WO 3 ·H 2 O nanosheets .
In this study, a gas sensor based on TiO 2 /WO 3 ·H 2 O (TW) heterojunction with high sensitivity, excellent selectivity and long-term stability for ammonia (NH 3 ) detection was successfully prepared by hydrothermal method . Compared with WO 3 ·H 2 O and TiO 2 , TW heterojunction shows excellent selective to NH 3 and the response varies by 3 orders of magnitude to 500 ppm NH 3 at room temperature (RT, 25 ± 3 °C). The lowest response limit of TW is 0.5 ppm and the response/recovery time is 2.35 s/1.95 s. The main reason for improving the performance of TW heterojunction to NH 3 detection is that TiO 2 nanoparticles cause more oxygen free radicals on the surface of TW heterojunction, which can react with more NH 3 molecules to release more electrons. Therefore, heterojunction structure increases the electrons and reduces the width of electron depletion layer in TW gas sensor. In addition, TW heterojunction has small and uniform particle size which can provide more active sites for the reaction between NH 3 and oxygen free radicals to release more electrons. This work provides a heterojunction structure composed of TiO 2 and WO 3 ·H 2 O to effectively improve the performance of sensor for NH 3 detection at RT, which is beneficial to the development of high-performance gas sensors.
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