Study On The Synthesis And Photocatalytic Performance Of The Ag₂CO₃-Based Composite Photocatalyst

The traditional type of photocatalysts such as TiO2 and ZnO mostly belong to the UV light response, which can not use 50～60% of visible light in sunlight energy. Thus the utilization of the solar energy is very low. It has abroad application value by researching and developing the high photocatalytic activity and high stability for the visible light response of the catalytic materials in environmental processing and energy conversion. Silver based semiconductor has a good visible light response performance. However, its photocorrosion which can lead to its poor stability and other shortcomings. Aiming at the characteristics of the silver based semiconductor, this paper systematically researched. Firstly, proposing use the Ag2CO3 with the wide band gap of TiO2 for coupling, which their band were matched, to improve the photoproduction electronic-hole separation, then prepared the high catalytic activity Ag2CO3/TiO2 heterojunction composite photocatalyst. Secondly, using the Ag2CO3 with narrow band gap AgX(Cl, Br, I) coupling forms the heterojunction can greatly improve the photocatalytic performance. Finally, with the graphene oxide(GO) and graphene(GR) excellent electronic conduction performance, the GO/Ag2CO3 and GR/Ag2CO3 were designed. The main research contents were shown following.1.Using TiO2 as a raw material, the Ag2CO3/TiO2 heterojunction composite photocatalyst synthesized by a simple precipitation and researched the photocatalytic activity under both UV and visible light irradiation in photocatalytic degradation of methyl orange (MO). The results showed that the photocatalytic activity of the Ag2CO3/TiO2 heterojunction composite photocatalyst obvious higher than that of pure Ag2CO3 and TiO2. The band structure calculation showed that Ag2CO3 and TiO2 had a matching potential can form the heterojunction structure, which can increase the separation efficiency of the e-/h+ pairs and restrain the recombination of e-/h+ pairs, therefore, resulting the photocatalytic activity and broadening the spectral response of TiO2.2.Researching the modification of Ag2CO3 by forming the heterojunction with the semiconductor coupling, the AgX(Cl, Br, I)/Ag2CO3 heterojunction composite photocatalysts synthesized by the coprecipitation methods. XRD, SEM, TEM, XPS and UV-vis DRS were applied to characterize these prepared products. The photocatalytic degradation of MO and stability test had been investigated. Results showed that the AgX(Cl, Br, I)/Ag2CO3 heterojunction composite photocatalysts showed extremely a high photocatalytic activity and stability. Lastly, discussing the mechanism of the AgX(Cl, Br, I)/Ag2CO3 heterojunction composite photocatalysts improve the photocatalvtic activity.3.Researching the modification of Ag2CO3 by graphene oxide (GO) and graphene (GR) doping, the GO/Ag2CO3 and GR/Ag2CO3 composite photocatalysts synthesized by a ultrasound deposition method. The influence of different dosages of GO and GR on the photocatalytic activity of composite photocatalysts were studied. Results showed that the composite photocatalysts showed extremely a high photocatalytic activity. Because GR had the excellent performance of large specific surface area, good electronic conductivity, stability and so on, it could effectively promote the separation efficiency of the e-/h+pairs, therefore, enhancing the photocatalytic activity of Ag2CO3.The above findings for the development of the new type and high efficiency visible light silver based semiconductor photocatalyst has certain theoretical guidance.