Controlled synthesis of defect-rich ultrathin two-dimensional WO3 nanosheets for NO2 gas detection

Ultrathin two-dimensional (2D) WO3 nanosheets (∼10 nm) were synthesized by a hydrothermal method and removal of surfactant templates. This synthetic strategy led to the formation of ultrathin 2D WO3 nanosheets with controlled oxygen vacancies. Ultrathin structure of WO3 with defect-rich exhibit a high response (∼6) for 50 ppb nitrogen dioxide at 140 °C. Meanwhile it has excellent selectivity to nitrogen dioxide against other examined gases (ethanol, carbon monoxide, hydrogen and ammonia) and environmental factors (carbon dioxide and humidity). The mechanism of material growth was studied by characterizing structural morphologies with scanning electron microscopy and transmission electron microscopy. The material’s gas-sensing mechanism was studied by measuring Brunauer-Emmett-Teller isotherms and recording electron paramagnetic resonance spectra.