Active W Sites Promoted by Defect Engineering Enhanced CHS Sensing Performance of WO Nanosheets.

Defect engineering has received extensive attention as an effective method to tune the gas sensing properties of semiconductor materials. Here, defective WO (D-WO) nanosheets were obtained by a simple hydrogenation process with a detection limit as low as 5 ppb for dimethyl trisulfide (DMTS) and a response of 2.3 times that of the initial WO nanosheets to 100 ppb DMTS. Importantly, X-ray photoelectron spectroscopy and Raman spectroscopy confirmed the partial loss of oxygen atoms in D-WO nanosheets, and density functional theory calculations found that the W sites near the oxygen defect showed higher adsorption energy for DMTS and transferred more electrons during the gas interaction, indicating that the active W site caused by oxygen atom loss can effectively enhance the reactivity of two-dimensional WO nanosheets. Different from the traditional oxygen defect model, this work reveals the positive effect of active metal sites on gas sensing for the first time, which is expected to provide an effective reference for the sensing application of defect engineering in metal oxides.