Fabrication Of SnS₂ Semiconducting Materials And Their Photocatalytic Property

At present,photocatalysis has been widely studied as an effective way to directly convert solar energy into chemical energy.However,due to the composition of the solar spectrum,it is very necessary to develop photocatalysts with visible light response.Since SnS2 has a narrow band gap energy(1.91-2.35 eV)and better performance than CdS(such as low toxicity,good chemical stability,and thermal stability),this makes it to be an attractive visible light-responsive photocatalyst.In this paper,SnS2 nanosheets with different sizes were synthesized by a simple hydrothermal method.The growth mechanism and photocatalytic properties of the SnS2 nanosheets were systematically studied.The effects of reaction condition on the crystallinity,morphology,photoresponse and carrier separation ability of the as-synthesized samples were investigated in detail.The main research contents and experimental results are summarized as follows:1.Using thiourea(CS(NH2)2)as sulfur source,regular hexagonal nanoplates of SnS2 single crystals with exposed {001} crystal facets were synthesized by changing the molar ratio of SC(NH2)2/SnC14 in the hydrothermal reaction solution,and the effect of hydrothermal reaction conditions on the composition,crystallinity,and morphology of SnS2-x products were investigated.It was found that the SnS2-6 regular hexagonal nanosheets hydrothermally synthesized from SnCl4 solutions with SC(NH2)2/SnCl4 molar ratios 6:1 have higher crystallinity and more ordered morphology than the irregular nanosheets,thereby exhibiting optimal visible light responsive hydrogen production activity.By adjusting the synthesis time and characterizing the properties of SnS2-6,the possible growth mechanism of hexagonal nanosheets was proposed.The current research results provide guidance for the controlled synthesis of MS2 series photocatalysts with highly efficient photocatalytic hydrogen production activity.2.The hydrogen production conditions for the SnS2 nanosheets synthesized in the previous chapter were optimized.The experimental results showed that SnS2-6 has the highest hydrogen production activity of 356 ?mol h-1(3 mg)reported in the visible light(??420 rm).with AQY of 9.43%at 420 nm monochromatic light.At the same time,combining various characterization methods,we explored the reasons for the differences in the hydrogen production activity of samples obtained under different reaction conditions.In addition,the catalytic mechanism of the high hydrogen production activity of the SnS2 nanosheets was investigated and speculated,providing guidance for the optimization of hydrogen production conditions for other sulfides.3.Change the sulfur source and use thioacetamide(TAA)to obtain hexagonal SnS2 nanosheets(labeled as SnS2-a)with smaller size,and apply the SnS2-a product to photocatalytic reduction of CO2.The characterization parameters of SnS2-a and the above SnS2-6 large-scale nanosheets(labeled SnS2-b)synthesized from CS(NH2)2 as sulfur source were comparatively analyzed,and the relationship between the structures and properties of SnS2 with different sizes was explored,providing guidance for the controlled synthesis of different size MS2 photocatalysts.