Structural and Microstructural Effects of Mo³⁺/Mo⁵⁺ Codoping on Properties and Photocatalytic Performance of Nanostructured TiO₂ Thin Films

Abstract

Mo 3+ /Mo 5+ equally codoped TiO 2 thin films (0.050−0.100 mol % individually) were fabricated by spin coating on polished fused silica glass substrates followed by annealing at 450 °C for 2 h. The highly transparent (>80%) films consisted of poorly crystallized single-crystal anatase, where interstitial solid solubility decreases the lattice parameters, with a reversed trend at the highest codoping level arising from supersaturation and V O •• formation. The crystallinities correlate with the alternating trends of peak intensities and shifts in both the glancing angle X-ray diffraction and Raman data. X-ray photoelectron spectroscopy data reveal the absence of any valence changes, indicating that intervalence charge transfer is not relevant. Although there are four potential midgap states that may alter the E g (Mo i, and V Ti ⁗), any effects from them on the performance would be mitigated by the annihilation of the charge-compensating V O ••. As the E g values correlate with the lattice parameters, the principal driver of the E g is the residual lattice compressive strain. However, the photocatalytic performance is principally a function of the crystallinity.

Design strategies for ceria nanomaterials: untangling key mechanistic concepts

“…7,55 Intervalence charge transfer (IVCT), involving electron exchange between dopant and matrix ions or between codopant ions, and multivalence charge transfer (MVCT), involving electron exchange between multiple-dopant ions and matrix ions, both without defect formation otherwise, represent underappreciated means of explaining valence changes. [56][57][58][59][60][61][62][63][64][65][66][67][68][69] Three types of colour centres (F 0 , F + , F ++ ) have been suggested by modelling 70 and validated experimentally for pure CeO 2Àx . 71 While, the latter were generated at room temperature, high-energy irradiation often is required to create the Schottky pairs that are involved in the generation of such F-centres.…”

Kinetic study of Fe & Co perovskite catalyst in Fischer–Tropsch synthesis

“…There are various methods for preparing perovskite oxide such as hydrothermal, microwave, precipitation, sol–gel, etc. 26 . The La Fe 0.7 Co 0.3 O 3 perovskite catalyst was prepared using the thermal sol–gel method.…”

Microwave-Assisted Solvothermal Synthesis of Mo-Doped TiO2 with Exceptional Textural Properties and Superior Adsorption Kinetics

“…Doping of TiO 2 with Mo triggered great interest, which aroused the radius of Mo 5+ (0.61 Å) and Mo 6+ (0.59 Å) and which are similar to that of Ti 4+ (0.605 Å). This means that Mo 5+ /Mo 6+ can effectively substitute Ti 4+ in its lattice structure with low lattice distortion [20]. Doping of TiO 2 with Mo cannot only influence the surface properties, but also affect the electronic and the optical properties and the material.…”

“…The photocatalytic performance of the prepared materials was investigated for photocatalytic reduction of CO 2 to methane. Similarly, Esposito et al demonstrated the synthesis of Mo-doped TiO 2 via a reverse micelle solgel approach using titanium butoxide and ammonium heptamolybdate tetrahydrate as metals precursors, cyclohexane as an oil phase, and polyoxyethylene (20) oleyl ether and Brij O20 as surfactants [26]. Their results exhibited that at Mo concentrations ≥ 2.5%, all phases of TiO 2 coexist, i.e., anatase, rutile, and brookite.…”