Orangnic Molecule Functionalized Graphene Composites: Preparation And Photocatalysis

Reduced graphene oxide functionalized composites by TPACH₂OH andRu-bipyridyl complexes dye molecules were prepared by noncovalent interactions,characterized and using the composites as photocatalyst for water splitting. The contentsof the paper are listed as follows：（1） The suspension of reduced graphene oxide （RGO） was prepared by thereduction of graphite oxide （GO） under alkaline conditions.4-（N, N-diphenylamine）benzyl alcohol functionalized graphene （TPACH₂OH-RGO） were formed by stirring themixture of TPACH₂OH and RGO at room temperature. Density functional method（DFT） studies show that hydrogen bond is present between TPACH₂OH and RGO inTPACH₂OH-RGO. The structure and photoelectric properties of TPACH₂OH-RGOconjugate were investigated by using UV-vis, Raman, fluorescence, AFM, TEM andelectrochemical method. The TPACH₂OH-RGO conjugate was employed as aphotocatalyst for H₂generation from water under ultraviolet-visible light illumination.The experiment results indicate that electron transfer occurred from the excited-state ofTPACH₂OH to RGO. With ethanol as electron donor, when the mass ratio ofTPACH₂OH to RGO is4/3, the total amount of H₂evolved from the TPACH₂OH-RGOsystem at pH6after6h irradiation was35.0μmol, which is higher than that producedfrom the RGO （20.4μmol）.（2） Ru（bpy）₃functionalized GO （Ru（bpy）₃-GO） and RGO （Ru（bpy）₃-RGO） wereprepared, which have stronger absorption in the visible light spectrum. The sampleswere characterized using UV-vis, Raman, Fluorescence, AFM, TEM, XRD andPhotocurrent. As shown in above experiments, the ability about Ru（bpy）₃attached onthe surface of the RGO and electron/energy between them is higher than GO. Underultraviolet-visible and visible light irradiation, Ru（bpy）₃-RGO exhibit more efficientactivity for hydrogen evolution from water than RGO with EDTA as electron donor. Itis good for photogeneration of hydrogen from warter that the UV absorption limit of photocatalyst tends to bathochromic shift and the percent absorption of visible light isobviously increased by the coupling effect of RGO and Ru（bpy）₃. The mass ratio ofTPACH₂OH to RGO and pH influence hydrogen evolution when Ru（bpy）₃-RGOemployed as photocatalyst; Ru（bpy）₃-RGO modified by Pt nanoparticles can furtherimprove the photocatalytic activity. All these features demonstrated that organicsensitizers functionalized graphene provided a nice candidate as a photocatalyst for H₂generation from water under solar light irradiation.（3） Ru（dcbpy）₃-RGO/Pt, A novel dye-sensitized photocatalysis for photochemicalenergy conversion was prepared. The samples were characterized using DFT, UV-vis,Raman, Fluorescence, AFM, XRD and Electrochemical tests. The excellentelectron-accepting and electron-transporting properties of RGO facilitate the electronstransfer from excited Ru（dcbpy）₃to Pt catalyst, which promotes the photocatalyticactivity for hydrogen evolution by investigating Fluorescence, photoelectrochemicaland photo-splitting water experiments. Under ultraviolet-visible and visible lightirradiation, Ru（dcbpy）₃-RGO/Pt exhibit more efficient activity for hydrogen evolutionfrom water than Ru（dcbpy）₃/Pt with TEOA as electron donor rather than the simplepiling up of the amount of H₂evolved from Ru（dcbpy）₃/Pt and RGO, this further provedthe helpful effect of RGO on the photocatalytic hydrogen generation from water. Thetotal amount of H₂evolved from the Ru（dcbpy）₃-RGO/Pt system is related to the massratio of Ru（dcbpy）₃to RGO and pH and Ru（dcbpy）₃-RGO/Pt show high stability in thephotocatalytic reaction.