Soft Chemical Synthesis And Photocatalytic Properties Of Bi₁₂TiO₂₀and Its Composites

With environmental pollution and energy crisis becoming more and more serious,the technology of using solar energy to deal with sewage has received widespread attention.The semiconductor photocatalysts have the advantages of direct utilization of solar energy,strong degradation ability and environment friendliness.As a new type of visible-light-driven catalytic material,the bismuth titanate based photocatalysts have become a hot spot in the field of photocatalysis.In this paper,a series of Bii2TiO20-based photocatalytic composites were prepared by a soft chemical route,and their photocatalytic properties were investigated in detail.The main contents include:1.Bi12TiO20 was prepared and characterized and its photocatalytic properties were investigated.The pure Bi12TiO20 powders were synthesized by an improved sol-gel method.The prepared samples are cubic phase and the average particle is about 200 nm.Rhodamine B(RhB)could be degraded over the Bi12TiO20 samples under visible light irradiation,and almost complete degradation was achieved within 360min.Compared with P25,the catalytic performance of Bi12TiO20 was significantly improved with excellent cyclability.The photocatalytic mechanism of Bi12TiO20 was revealed by analyzing the band edge position and the active species from the radical trapping test.2.The Bii2TiO20/GO composites were prepared,and the enhanced photocatalytic properties were investigated.In order to improve the quantum efficiency,graphene oxide was introduced to prepare the Bi12TiO20/GO composite photocatalyst,and the optimal loading of GO was explored.The Bii2TiO20/10%GO sample has the highest photocatalytic activity and can completely degrade RhB within 240min under visible light irradiation without at the cost of the cyclic performance.The introduction of GO can help the electron transfer in the hybridization system and promote the separation of carriers to boost the photocatalytic performance.3.The Bi12TiO20/g-C3N4 composites and the Z-scheme mechanism were studied.The g-C3N4 nanosheets were first prepared and then Bi12TiO20/g-C3N4 composites were constructed.The optimal ratio of Bi12TiO20 to g-C3N4 was also explored.The 0.5BTO/CN sample shows the highest photocatalytic activity.In the degradation experiment,RhB was thoroughly degraded within 120min,and the photocatalytic efficiency of 0.5BTO/CN is improved by 4.9 times than that of the pure phase Bii2TiO20.The main active species in photocatalytic degradation were verified as ·OH and ·O2-.The carriers transport in this composite system follows the Z-scheme mechanism,which can effectively separate photo-generated carriers,and thus the photocatalytic performance was greatly improved.