| Recently,energy depletion and environmental pollution are two major problems that human development needs to be solved urgently.Looking for green clean energy and developing efficient pollution control technology has attracted the attention from all over the world.Semiconductor photocatalysts are one of the most effective ways to solve environmental and energy problems due to their low cost,non-toxic,wide range of sources and no secondary pollution and have been widely used.However,large-scale application of photocatalyst still has many problems,including two aspects:(1)low solar energy utilization,(2)low quantum efficiency.Therefore,the search for new semiconductor photocatalytic materials with excellent performance has become the most important topic in the field of photocatalysis.Fullerenes and their composite nanomaterials have broad application prospects due to their unique geometrical structure and special electronic properties in the field of semiconductor photocatalysis.In this paper,the electronic structure and optical properties of fullerene/semiconductor nanocomposites have been studied based on the first-principles of density functional theory.The results are as follows:(1)The photocatalytic activity and stability of four kinds of fullerenes(C20,Li@C20,C26 and Li@C26)have been investigated.The result shows that the fullerene/Ag3PO4(100)nanocomposites have smaller bandgap(1.92,2.04,0.78 and 0.66 eV)than the pure Ag3PO4,thus extending the absorption spectrum covering the entire visible region,and even in the infrared region.The type-?,staggered,band alignment existing between the C26(Li?C26)and Ag3PO4(100)surface can promote the separation of photoinduced carriers,thus enhancing the photocatalytic activity.As Li atom is embedded in C20(C26),the Li donating an electron to C20(C26)and enhances intermolecular electrostatic interactions compared to pristine C20(C26).As a sensitizer,C26 is expected to arise in other fullerene,Ag3PO4 semiconductor nanocomposites.These findings provide a theoretical basis for developing highly efficient Ag3PO4-based or fullerene-based photocatalysts.(2)Taking molybdenum disulfide as an example,the effect of interfacial interaction on the electronic structure and optical properties of two-dimensional transition metal sulfide/fullerene have been systematically studied.The analysis shows that the molybdenum disulfide/fullerene heterojunction has a small bandgap(1.75,0.41 and 0.85 eV),thus extending the absorption spectrum covering the entire visible region.The type-?,staggered,band alignment existing between monolayer MoS2 and C20 can promote the separation of photoinduced carriers,thus enhancing the photocatalytic activity,and MoS2/C20 composites also have the ability to oxidize water to produce oxygen or oxidize organic matter.These findings provide a theoretical basis for developing highly efficient MoS2-based or fullerene-based photocatalysts.(3)The electronic structure and photoactivity of monolayer two-dimensional materials WS2(MoS2)have been investigated by non-covalent functionalized small fullerenes B12 and C20.It is unveiled that the fullerene can act as a sensitizer in monolayer WS2(MoS2)to improve the photoactivity.Compared to pure monolayers,the heterostructures have smaller band gap(1.31,1.45 and 0.93 eV),which is in favor of enhancing the visible light absorption.The type-?,staggered,band alignment is formed between WS2(MoS2)and fullerene with the latter possessing the higher electron affinity,resulting into the robust separation of photoexcited charge carriers between them.It is expected that B12 and C20 act as a sensitizer in other fullerene-semiconductor heterostructures.This strongly suggests possible applications in photocatalysis.Our results provide novel insight into the understanding of the effect of heterostructures,which will help not only in understanding the mechanism of photocatalysis but also in designing new heterostructures for photocatalytic reactions. |
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