Vertical Few-Layer WSe₂ Nanosheets for\nNO₂ Sensing

Abstract

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