Preparation Of Graphene Based Semiconductor Nanocomposites For Photocatalytic Reduction Of CO₂

The photocatalytic conversion of CO2into renewable hydrocarbon fuels is believed to beone of the best methods to overcome both the energy crisis and environmental problems. Todesign an efficient photocatalyst is a key factor in improving the photocatalytic activity.Graphene can be used as an ideal supporter to improve the photoelectric property ofsemiconductor nanomaterials, due to its unique electronic transmission capacity.Graphene-based semiconductor materials has become the focus of the world attention for itsphotocatalytic application. In this work, we try to prepare a series of graphene-basedsemiconductor photocatalysts, and research their photocatalytic activities of reduction CO2.The main contents are given as follows:Reduced graphene oxide (rGO)-TiO2nanotube composites were synthesized by a simpleone-pot hydrothermal method using graphite oxide and titanium dioxide as raw materials andgraphite oxide was prepared by modified Hummers method. The samples were characterizedby X-ray diffraction (XRD), Transmission scanning electron microscopy (TEM), Fouriertransform infrared spectra (FTIR), and UV-vis diffuse reflectance (DRS). The photocatalyticperformance were researched for the reduction of CO2under simulated sunlight irradiation.Characterization results indicate that: TiO2nanotubes are uniformly loaded on the surface ofrGO nanosheets; The introduction of rGO widens TiO2nanotube response range towards light.Experimental results show that: The photocatalytic activity of catalyst in the reduction of CO2is obvious enhanced after incorporating appropriate rGO and TiO2nanotube; Under theconditions of graphene oxide mass fraction5%and photocatalyst dosage1.5g/L, the activityof rGO-TiO2nanotube composite is four times as higher as that of TiO2nanotube; TherGO-TiO2nanotube composites possess excellent cycling property. A series of zinc oxide/reduced graphene oxide nanocomposites (ZnO-rGO) werefabricated by a facile one-step hydrothermal method. The composite materials werecharacterized by X-ray diffraction (XRD), Transmission scanning electron microscopy (TEM),Energy dispersive X-ray analysis (EDX), X-ray photoelectron Spectroscopy (XPS), nitrogenadsorption-desorption isotherms, photoluminescence spectra (PL) and UV-vis diffusereflectance (DRS). The photocatalytic performance of the ZnO-rGO composites wasinvestigated towards photoreduction of CO2to CH3OH. The yield of CH3OH on ZnO-rGOwas five times as higher as that on pure ZnO. The ZnO-rGO nanocomposites possess ecellentreusing and cycling property.Reduced graphene oxide-Bi2S3nanorod composites (rGO-Bi2S3nanorod) are synthesizedthrough a facile solvothermal approach using ethylene glycol as solvent and reducing agent.The obtained samples are characterized by powder X-ray diffraction (XRD), scanningelectron microscopy (SEM), transmission electron microscopy (TEM), Fourier transforminfrared spectra (FTIR), thermogravimetric analysis (TGA), and UV-visible diffusereflectance spectroscopy (DRS). The photocatalytic activities of the samples wereinvestigated by the reduction of CO2under visible light irradiation. The results indicate thatBi2S3nanorods with a diameter of30-40nm and a length of100-200nm are decorated on thesurface of graphene sheets optionally and rGO-Bi2S3nanorod exhibits an enhancedphotoreduction activity than pure Bi2S3nanorod.