Oxygen Effect on the Structural, Optical and Electrochemical Properties of Radio Frequency Sputtered SnO2 Thin Films for Photocatalytic Degradation of Methylene Blue

Tin oxide thin films were synthesized on FTO substrates by the Radio Frequency sputtering technique in aO₂/Ar mixture atmosphere. X-ray diffraction patterns revealed the formation of tetragonal structure of SnO2 films, with a crystallite size that increases from 8.3 to 10.3 nm by increasingthe oxygen percentage from 5% to 15%, then decreases again at 30%oxygen. SEM images reveal homogeneous, smooth, non-porous and crack-free surfaces in all films. EDX spectra confirm the increasing O/Sn ratio for high oxygen percentages. Optical transmittance is observed toincrease with increasing the oxygen percentagewith an energyband gap ranging between 3.78 and 3.91 eV. Mott-Schottky characterization shows higher charge carrier concentration in the film synthesized with 10% O₂. This film exhibits, afterwards, the highest efficiency in terms of degradation of in a UV photoreactor.