Efficient Gas Sensor Devices Based on Surface Engineered Oxygen Vacancy Controlled TiO2 Nanosheets

Systematic optimization of the surface attributes (structural and morphological) as well as the defect states [oxygen vacancies (OVs)], for achieving efficient alcohol sensing by TiO2 nanosheets, is the central focus of this paper. Variation in the surface roughness and the OVs of hydrothermally grown TiO2 nanosheets were achieved by varying the ethanol and water content in stepwise manner, keeping the NaOH concentrations in the electrolyte unchanged. Structural, morphological, and optical characterizations, such as field emission scanning electronmicroscopy and X-ray photoelectronspectroscopy, revealed that with increase in ethanol concentrations, surface roughness increased (at a particular water concentration), while at a fixed ethanol concentration, OVs increased with decrease in water concentrations. The sensor derived through the minimum water content and the maximum ethanol content offered the most promising sensor response owing to availability of the maximum amount of OVs with the highest surface roughness.