فهرست نشریات علمی دسترسی آزاد ایران

The current research aimed to improve the structural, optical, and sensing properties of vanadium pentoxide (V2O5) thin films produced via spray pyrolysis on varying substrate temperature (300–500 °C). Findings demonstrate that increasing the temperature drastically enhanced the crystal structure, as demonstrated by increased X-ray diffraction (XRD) peaks with the development of orthorhombic crystal structure. An increase in grain size is noted from approximately 16.5 nm at 300 °C to approximately 28.7 nm at 500°C according to the Scherrer equation, with a reduction in density of crystalline dislocations. The films showed quite low absorption in the visible region, with the optical energy gap (Eg) increasing from 3.15 eV to 3.7 eV as the temperature increased. This was attributed to quantum confinement and improved crystal development, and shown by AFM images of atom beam microscopy of a smooth surface with larger grain size and less defect on the surface at higher temperatures. In gas sensing tests, films deposited at 400 °C exhibited very significantly increased sensitivity to propane (C₃H₈) and carbon monoxide (CO) at 150 °C but had the highest sensitivity to nitric oxide (NO) at 50 °C. This is due to the process of redox reaction occurring on the surface of V2O5 in which reducing gases like CO enhance the conductivity by liberating electrons while oxidizing gases like NO lower the conductivity by capturing electrons. The thus research established that substrate temperature control during fabrication is necessary to achieve optimal features of V2O5 with a potential promising application for nonlinear optical devices, lithium batteries, and high-performance, low-cost gas sensors.