Synthesis Of Metal Oxides （TiO₂、α-Fe₂O₃） Nanocrystals Dominated With High-energy Facets And Their Performance Of Photocatalytic Reduction Of Uranyl Ions

With the rapid development of current nuclear power, nuclear industry havegenerated amount of waste water containing radioactive uranium. Uranyl ion as amainly form exist in waste water containing uranium. If not treat before discharge,uranyl ions of easy migration enter into the organism through the food chain, whichcan serious affect biological healthy. If we can achieve the recovery of uranium fromradioactive, which can not only reduce environment hazards but also gain valuableuranium resources. Theoretical analysis and several preliminary experiments showedthat photocatalytic reduction of uranyl ions in water could happen over TiO2to givethe low-valence uranium oxide precipitate, which is easily to recover.It is well known that the surface morphology of metal oxides have a veryimportant impact on its photocatalytic properties. Therefore, the metal oxides withhigh-energy crystal facets dominated become a hot research topic for their potentialhigh performance in photocatalysis.The main work of this thesis is as follows:1、 Anatase TiO2nanocrystals with {101},{001} or {100} dominant facetswere controllable synthesized by facile hydrothermal methods and used for thephotocatalytic reduction of uranyl ions under UV radiation. It was found that thereduction ability based on the equal surface area of different anatase crystal facets canbe ranked as:{100}>{001}>{101}, which may be attributed to the surface atomicand electronic structure of different facets.2、Rod-shaped rutile TiO2nanocrystals with various aspect ratios (5、3、2) wereprepared by a two-step wet-chemical method using NaCl and NaClO4as the hydrolysis control agent and their photocatalytic performance for reducing uranyl ionsunder UV irradiation were investigated. The reduction ability based on the equalsurface area of rutile nanorods can be ranked as: R2> R1> R3. Synergistic effectbetween {111} and {110} facets would account for the difference in catalyticperformance of rutile TiO2nanorods.3、Hematite (α-Fe2O3) nanocrystals with {101},{001} or {104} dominantfacets were selectively synthesized via a facile hydrothermal process. The reductionability on different α-Fe2O3crystal facets per unit surface area of photocatalyticreduction of uranyl ions were investigated under visible-light radiation. It may beattributed to the unsaturated density of Fe atoms on the different crystal facets affectsthe activity difference photocatalytic reduction of uranyl.