Preparation And Application Of BiVO₄/Graphene Composites

Photocatalytic technology of semiconductor material has good prospects in the field of environmental protection. Bismuth Vanadate is a narrow-band-based semiconductor material which has high catalytic performance. As it has small surface area and its hole-electron pairs can be easily compounded, its photocatalytic properties have much room for improvement. Graphene is a two-dimensional material with strong conductivity, zero band gap and high specific surface area. BiVO4 composites with graphene to prepare composite materials which can improve the photocatalytic properties of BiVO4 and generate synergies. In this paper, butterfly-shaped flakes BiVO4/graphene composites and chip stacked BiVO4/graphene composites was prepared by hydrothermal method and microwave method. And through a variety of characterizations, polymorphs, appearance, elements, bandgap and the photocatalytic activity of composite materials and pure substances were researched. In this paper, main research contents and conclusions were as follows:1. BiVO4/graphene composite material by hydrothermal method and its application. In this part, different composite material were prepared by different proportions of graphite oxide and BiVO4, and photocatalytic properties of each kind of composite materials were researched, finally the best one was chose to characterize. The experimental results show that GB40 (40mg GO:lmmol BiVO4) is the optimal one. In this kind of composite material, BiVO4 is butterfly-type sheet, and the aspect ratio is between 2.5-3.0, the longest side is about 70-150 nm. 100mg of BiVO4/graphene composite was used to photocatalytic reduce 100 mL of 10 mg/L Cr (VI) solution. When illumination time is 150 min, Cr (VI) has been removed 95.6%, which is about 2.5 times if BiVO4 was used. In the application of photocatalytic reduction of CO2, after lighting 10h, ethanol yield reached 57.8 μmol/L by BiVO4/GN catalyzed, which is 27.3% higher than pure BiVO4.2. BiVO4/graphene composite material by microwave method and its application. The optimal reaction time, material ratio, add order of reaction materials and their photocatalytic properties were researched by experiment. Experimental results show when the microwave reaction time was 15min, the material ratio was GB30 (30mg GO:lmmol BiVO4), Bi(NO3)3·5H2O was added in the first, the composite material with a stable crystal form and high catalytic activity could be prepared. The BiVO4 in the composite material was piled by slices which the thickness is 20-25nm.100Omg of BiVO4/graphene composite was used to photocatalytic reduce 100 mL of 10 mg/L Cr (VI) solution. When illumination time is 150 min, Cr (VI) has been removed 90.32%, which is about 2.5 times if BiVO4 was used.