BiVO₄/r Go Composite Preparation And Its Photocatalytic Performance Of CO₂ Reduction

Global warming caused by CO₂ emission is one of the severe challenges that humanity faces today,and that need to be solved to realize sustainable development in China and the rest of the world.Since the long-time use of fossil fuels as a primary energy source is unavoidable,CO₂ capture from large point source emitters and conversion of CO₂ into energy and useful chemicals provide an efficient solution to mitigate carbon emission.Photocatalysis,developed in recent years,is a green low-carbon technology that directly uses solar light to reduce CO₂.Developing efficient photocatalysts is the essence of photocatalytic technology,and semiconductor/carbon composites have attracted great attention due to their potential application in photoreduction of CO2.Bismuth vanadate?BiVO₄?has attracted extensive attention due to its narrow bandgap and high photocatalytic activity under visible light irradiation.In this paper,Bi?NO?₃·5H₂O and NH₄VO₃ were used as bismuth and vanadium source,respectively,and micro-nanostructured BiVO4 and BiVO4/rGO composites with a diversity of morphologies were successfully prepared by different hydrothermal processes.The morphology and microstructure of as-synthesized catalysts were characterized with the aid of various techniques,such as Fourier transform infrared spectroscopy?FTIR?,Raman spectrum,X-ray diffraction?XRD?,X-ray fluorescence spectroscopy?XRF?,transmission electron microscopy?TEM?,scanning electron microscope?SEM?and UV-vis diffuse reflectance spectra?UV-vis/DRS?.Photocatalytic activities of the obtained BiVO₄ and BiVO₄/rGO composites for reduction of CO₂ under Ultraviolet-visible light irradiation were evaluated by monitoring the formation of methanol.Coral-like BiVO₄ and BiVO₄/rGO composites was prepared by using the microwave-assisted hydrothermal method,and the photocatalytic performance of the composites on CO2reduction shows that the optimum mass ratio of graphene was 3%.When the xenon lamp power was 600 W,the methanol yield was 501.84?mol/L after 6 h,which was 82.97%higher than that of pure BiVO_4.Granulated and rod-like BiVO4,BiVO4/rGO composites were prepared with hexadecyl trimethyl ammonium bromide?CTAB?used as surfactant and without surfactant,respectively.The photocatalytic activity of the as-synthesized samples shows that the optimum mass ratio of graphene was 3%.When the xenon lamp power was 600W,the methanol yields were 536.64?mol/L and 513.12?mol/L after 6 h,which was 74.81%and73.58%higher than pure BiVO4,respectively.CO₂ can be selectively reduced to methanol by the as-synthesized micro-nanostructured BiVO4 and BiVO4/rGO composites with a diversity of morphologies.The yield of methanol was significantly increased when BiVO₄ was doped with graphene,and the optimal amount of graphene was 3 wt%,regardless of what the morphology of the composite you obtained.The enhanced photocatalytic performance of BiVO₄/rGO composites could be assigned to narrowing bandgap of BiVO₄ and increased charge separation efficiency and adsorption sites due to the presence of graphene in the composites.However,graphene may cover BiVO₄active catalytic sites,the photocatalytic activity of BiVO₄/rGO decreased when too much graphene was combined with BiVO₄.