Water Splitting And Propylene Epoxidation Performance With Structure-Activity Relation Of TiO₂-based Catalysts

TiO2-based catalysts are widely used in photocatalytic water reduction reaction and propylene epoxidation reaction.In this thesis,several TiO2-based materials were prepared and studied as catalysts for photocatalytic water reduction reaction and propylene epoxidation reaction.The main results are as follows:1.Pt/Cu2O-TiO2 catalysts were prepared by photodeposition of Pt on Cu2O-TiO2 composite surfaces employing H2PtCl6 aqueous solution as the precursor,in which a key role of isoelectric point of oxide surfaces on the Pt photodeposition process was revealed.Under the photodeposition conditions,Pt metal particles are facilely photodeposited on TiO2 support;on Cu2O-TiO2 composite supports,the Cu2O surface is positively charged and enriched with photo-excited holes while the TiO2 surface is negatively charged and enriched with photo-excited electrons.This leads to the preferential adsorption of PtCl62-anion precursor on the Cu2O surface of Cu2O-TiO2 composite and the dominant formation of Pt oxide particles on Cu2O surface but few Pt metal particles on TiO2 surface.Consequently,the activity of resulting Pt/Cu2O-TiO2 composite photocatalysts in photocatalytic water reduction decreases as the Cu2O content increases.These results deepen the understanding of photodeposition processes on oxide composite surfaces.2.Anatase TiO2 nanosheets with different ratios of{001} facets were prepared via adjusting the hydrothermal temperature and the amount of HF(aq)capping agent during the hydrothermal method,and used as photocatalysts for photocatalytic water reduction.The catalyst with a larger proportion of{001} facets is more active among TiO2 nanosheets prepared using the same amount of HF(aq)capping agent,while the one with a smaller size is more active among TiO2 nanosheets prepared at the same hydrothermal temperature.3.1%-Au/TiO2 {001} catalysts were prepared by precipitation deposition method with ammonia as a precipitant using anatase TiO2 nanosheets with different ratios of{001} facets as supports and used as catalysts for propylene epoxidation.The catalyst with a higher ratio of {001} facets shows a larger propene oxide yield,indicating that the anatase TiO2 {001} facets in Au/TiO2 catalysts benefit the propylene epoxidation reaction.