Theoretical Study On The Electronic Structure And Photocatalytic Performance Of Two-Dimensional SiC Heterostructure

The preparation of clean energy by semiconductor photocatalysis technology is a research hotspot at present,and the continuous maturity of semiconductor photocatalysis technology plays an outstanding role in relieving energy pressure and restraining environmental pollution.In this paper,the electronic structure and photocatalytic mechanism of g-SiC/MoSSe and g-SiCAVSSe heterostructures are studied by first-principles calculation.The structural stability of the two heterostructures was studied through different methods.Their electronic structures,light absorption properties and photocatalytic mechanism were accurately described by using HSE06 hybrid functional.Firstly,we studied the g-SiC/MoSSe heterostructure through formation energy,phonon dispersion spectrum and AIMD simulation to ensure the geometric stability.The calculation results of electronic structure show that the g-SiC/MoSSe heterostructure exhibits the semiconductor property of indirect band gap with a type Ⅱ band alignment.The band gap value is 1.91 eV which is smaller than the g-SiC and MoSSe monolayers.Layered aggregation of photogenerated electrons and holes at the interface of g-SiC/MoSSe heterostructure plays an important role in improving carrier mobility,inhibiting recombination of photogenerated electrons and holes and enhancing photocatalytic efficiency.The absorption spectrum shows that the light absorption coefficient of g-SiC/MoSSe heterostructure in visible region reached 6.2×105·cm-1.In addition,the photocatalytic performance of g-SiC/MoSSe heterostructure was tested under different pH(0-7),and the photocatalytic performance of g-SiC/MoSSe heterostructure all met the requirements of photolysis of water.In a word,g-SiC/MoSSe heterostructure can be used as a potential high-efficiency photocatalyst with great application prospect in visible light region.Secondly,the g-SiC/WSSe heterostructure was also studied in detail.The geometric structure of g-SiC/WSSe heterostructure is also stable.The electronic structures of g-SiC/WSSe heterostructure indicated that it is an indirect band gap semiconductor with type Ⅱ band alignment.The type Ⅱ band alignment and indirect band gap can inhibit the recombination of photo-generated carriers in the process of migration.The band gap value of g-SiC/WSSe heterostructure is 1.61 eV which is also smaller than the g-SiC and WSSe monolayer.The g-SiC/WSSe heterostructure possess a strong absorption coefficient reached 4.8 × 105·cm-1 in ultraviolet light.The photocatalytic performance of g-SiC/WSSe heterostructure was different under different pH medium.The condition of hydrogen production by photocatalytic water decomposition was met at pH=0,but it does not meet the requirements of photocatalytic water decomposition under weak acid conditions(pH=3).In conclusion,g-SiC/WSSe heterostructure can be used as a good photocatalyst to effectively decompose water under ultraviolet light.