Synthesis And Photocatalytic Performance Of Transition Metal Oxides/2D G-C₃N₄

Semiconductor photocatalysis has great advantages in solving the energy crisis.The core of photocatalysis is photocatalyst.Graphitic carbon nitride?g-C₃N₄?with low cost,high efficiency and stability have attracted much attention,has been widely used in visible photocatalytic hydrogen production.The interlayer van der Waals force of g-C₃N₄ is weak,which has the potential to form graphene-type nanosheets with unusual physical and chemical properties.Two-dimensional graphitic carbon nitride?2D g-C₃N₄?nanosheets have attracted great attention due to their potential applications in the fields of electronics,sensors,catalysts and energy storage.Compared with the bulk g-C₃N₄,2D g-C₃N₄ has a higher specific surface area,a more suitable band gap,the improved electron transfer ability along the plane direction and the increased life of photo-generated carriers due to quantum confinement effect.Herein,the paper focuses on improving the activity of 2D g-C₃N₄ by combining morphology control and semiconductor composite method.That is,coupling the 2D g-C₃N₄ with Ta₂O₅ nanorods,Nb₂O₅ nanoflowers,V₂O₅ nanosheets respectively to construct 1D/2D,3D/2D and 2D/2D composites to enhance its photocatalytic performance.The specific research results are as follows:?1?Ta₂O₅ nanorod was synthesized by a simple hydrothermal method.Then,Ta₂O₅ nanorods and g-C₃N₄ materials are linked together by calcining method to prepare a novel Ta₂O₅/2D g-C₃N₄ composite with 1D/2D structure.The chemical composition,structural information,microstructure and optical properties of the synthesiszed photocatalysts were analyzed by XRD,FT-IR,XPS and so on.Under the visible light irridation,the Ta₂O₅/2D g-C₃N₄?13.6%?presented a high H₂ evolution rate about 1.9×10⁴?mol g^-1 h^-1 with external quantum efficiency?EQE?of 12.48%at?=420 nm.?2?Nanoflower-like Nb₂O₅ material was synthesized by hydrothermal method.Then,2D g-C₃N₄-based composites were prepared by calcining method.A small amount of Nb₂O₅ nanoflower can significantly accelerate the exfoliation of g-C₃N₄.The chemical state of elements,microstructure and grain morphology of the samples were analyzed by XRD,XPS,TEM,ESR and others.The Nb₂O₅/2D g-C₃N₄?10.4%?composites presented a high H₂ evolution rate about 2.1×10⁴?mol g^-1 h^-1 with EQE of14.75%at?=420 nm and a superior turnover frequency?TOF?of 146.9 h^-1.?3?The two-dimensional V₂O₅ nanosheet was obtained by exfoliating commercial bulk V₂O₅ materials by gas phase stripping method.Then a simple calcining method was used to prepare two-dimensional composite photocatalytic materials.The crystal structure,microstructure and photoelectric property of samples were analyzed by XRD,DRS,TEM,ESR and so on.2D/2D hybrids with a facile calcination method show the tight interfaces and a novel all-solid-state Z-scheme junction.The tight contact interface of 2D/2D in the composite is beneficial to shorten the transmission distance of the photo-generated carrier and promote its separation.Besides,the V₂O₅ nanosheet/2D g-C₃N₄ Z-scheme nanostructured hybrids present a high H₂ evolution rate².3×10⁴?mol g^-1 h^-1,EQE of 19.38%at?=420 nm.