Oxygen Effect on the Structural, Optical and Electrochemical Properties of Radio Frequency Sputtered SnO<sub>2</sub> 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 SnO 2 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.