Acid Strontium-doped Yttrium Zirconium - Titanium Dioxide Heterojunction Light Catalyst And Its Photocatalytic Activity Study

Sr(Zr_1-xY_x)O_3-δ-TiO₂ heterojunction photocatalysts were prepared bysolid sintering method and sol-gel coating method. The photocatalystswere characterized by XRD, SEM, FT-IR TG-DTA and UV-vistechniques. The photocatalytic degradation of methylene blue (MB) inaqueous solution and photocatalytic generation of hydrogen in oxalic acidsolution were used as the probe reactions to evaluate the photocatalyticactivity of the photocatalyst. The effects of preparation method, TiO₂amount in the heterojunction photocatalyst, and deposition of noble metalon the photocatalytic activity of photocatalyst were also discussed.Sr(Zr_1-xY_x)O_3-δTiO₂ photocatalyst prepared by solid sinteringmethod had higher activity under UV-light or visible light irradiation.The photocatalytic activity of composite particles was higher than that ofpure TiO₂ and pure Sr(Zr_1-xY_x)O_3-δ. The quickly recombination ofphotogenerated electrons and holes were restrained by the heterojunctionformed in composite particles. Preparation method of SrZrO₃, dopingcontent of yttrium and different proportion of TiO₂ in the heterojunctionshave influence on the photocatalytic activity of the catalyst. The bestdoping content of yttrium was 5%. The optimal content of TiO₂ incomposite particles was 90 mass%, 70 mass% respectively underUV-light and visible light irradiation, the degradation rates of MB was98.8% and 93.5%, respectively after 50 min irradiation.Sr(Zr_1-xY_x)O_3-δ-TiO₂ heterojunctions were also prepared by sol-gelcoating method under different conditions. The visible lightphotocatalytic activity of catalysts was discussed. The optimalpreparation condition was obtained by experiments: The content of TiO₂in heterojunctions was 70 mass%, the sintering temperature was 800℃and the sintering time was 1 hour. The sample prepared under optimizedconditions showed a higher photocatalytic activity than catalysts preparedby solid sintering method, the degradation rates of MB(25 mg/L) was99.0% after 50 min irradiation of visible light.A suitable Ag loading could greatly enhance the heterojunctionphotocatalytic activity. The optimal content of Ag loading was 0.25 mol%. After loading, the final degradation rates of MB(25 mg/L) raisedfrom the original 93.5% to 99.3% and the initial rate was 1.4 times of thatp revious. The Pt-Sr(Zr_1-xY_x)O_3-δ-TiO₂ photocatalyst with varying Ptloadings was also prepared by the photodeposition method and itsphotocatalytic activity was tested using photocatalytic hydrogengeneration in oxalic acid solution as the model reaction. The effects of thecontent of Pt loading, preparation method on the activity of catalyst werestudied. The results showed that Pt-Sr(Zr_1-xY_x)O_3-δ-TiO₂ catalysts hadhigh photocatalytic activity of hydrogen generation. The content of Ptloading, preparation method, the concentration of oxalic acid and pHvalue of solution have importance influence on photocatalytic hydrogengeneration. The optimal loading content of platinum was 0.458 mol%.Under this condition, the average rate of photocatalytic hydrogengeneration was 1.68 mmol/h when the concentration of oxalic acid was50 mmol/L and the concentration of catalyst was 1.0 g/L.