Metal-quinoline Complexes Sensitized TiO₂Nanoparticles With Enhanced Visible Light Photocatalytic Activity

Titanium dioxide, one of the most promising photocatalysts, has manyadvantages such as chemical stability, easy availability, energy-saving and non-toxicity. However, TiO2can only be excited by ultraviolet (UV) irradiation due to itswide band gap energy (3.2eV). Because the UV light accounts only for5%of totalsolar light, TiO2cannot be widely used in practice when aiming at using the solar lightas renewable energy source. Dye sensitization is one of the effective methods toextend the range of TiO2visible light response, However, the pure organic dyes arelimited by the poor charge transfer and low photochemical stability. On the other hand,ruthenium is an expensive and toxic element which limits the application of the Ru-dye. In the present work, we employed8-hydroxyquinoline-5-sulfonic acid iron (Fe-HQS) and8-hydroxyquinoline-5-sulfonic acid erbium (Er-HQS) to sensitize TiO2nanoparticles respectively. Metal-quinoline complexes sensitized TiO2nanoparticleshowed high photocatalytic activity and photochemical stability during thephotodecomposition of phenol in an aqueous solution than the simple TiO2nanoparticles were used. Specific work is as follows:1. Er-HQS and Fe-HQS complex were prepared by heating reflux method usinganhydrous ethanol as solvent and characterized by ultraviolet-visible absorptionspectra and photoluminescence spectrum.2. Er-HQS-TiO2and Fe-HQS-TiO2nano composite catalyst were synthesized by thehydrothermal method, respectively. XRD, TEM, SEM, UV-Vis-DRS were used tocharacterize the bulk phase and surface structure of samples.3. The photocatlytic degradation phenol was investigated in metal-quinolinecomplexes sensitized TiO2nanoparticle aqueous suspensions under trichromatic lampirradiation. The effects of hydrothermal time, hydrothermal temperature and theamount of metal-quinoline compounds doped were investigated to determine theoptimum hydrothermal synthesis conditions.4. The influence of the catalyst dosage, catalyst reuse and different catalyst on thephotocatalytic degradation effect was investigated. Irradiation for t time under visiblelight95.26%and94.39%of phenol can be degraded in the present of Er-HQS-TiO2and Fe-HQS-TiO2, respectively. The twice-recycled photocatalyst still showed goodphotocatalytic activity, indicating that the M-HQS sensitized TiO2catalyst was photostable.5. Using density functional theory (DFT) B3LYP method calculated the potentialenergy of metal-quinolin compounds and compared it with the experimental results.Moreover, the process of photocatalytic dynamics principle including conversionphotoluminescence, energy transfer and dye photosensitive were discussed.