Vertical Few-Layer WSe2 Nanosheets for NO2 Sensing

WSe2 has been widely used in NO2 gas sensors in recent years, but it still suffers from low responsiveness and slow reaction kinetics. Herein, we used the chemical vapor deposition method to synthesize a vertically grown few-layer WSe2 (3D-WSe2) nanosheet film. Three-dimensional-WSe2 is transformed into vertical growth by introducing a TiO2 buffer layer and exposes much more edge active sites to improve gas sensitivity. As a result, it has not only high crystallinity and few defects but also a high response to NO2 (34.6% at 1 ppm), a fast response time (66 s), a short recovery time (17 min), a low limit of detection (4 ppb), excellent stability, and gas selectivity at room temperature.