Fabrication Of Semiconductor Nanocrystal Composites And Application In Photoelectrocatalysis And Heavy-Metal Adsorption

Semiconductor nanomaterials can be used to produce new energy(hydrogen)and solve environmental pollution problems as they have the proper band structure,large specific surface area and unique surface effect.However,in practical applications,single semiconductor nanomaterial may not meet our needs,or the performance is not good enough.In this paper,the composite structures of semiconductor nanomaterials are designed to improve the performance of the materials and make up for the defects of single material.The main results obtained are described as follows:1.Silicon carbide(SiC)nanocrystals with surface autocatalytic effect can be used for electrochemical hydrogen production.The energy to produce oxygen is higher than that of hydrogen,so SiC nanocrystals can not produce oxygen by itself.In the composite structure of 3C-SiC nanocrystals and zinc oxide(ZnO),ZnO nanowires will produce holes when illuminated by Xe light.The photogenerated holes can be efficiently transferred to 3C-SiC nanocrystals,so that SiC nanocrystals with surface autocatalytic effect can be used for electrochemical oxygen production.2.Graphene oxide(GO)is a good adsorbent for heavy-metal ions because the oxygen functional groups offer active adsorption sites.The adsorption capacity can be improved by increasing the amount of the oxygen functional groups.However,small-size GO with dense oxygen-containing groups increase the water solubility making separation difficult,and a possible solution is to produce a cluster which can coordinate with small GO.Such design can retain the adsorption capacity of the oxygen-containing groups and make the composites easily to be removed from the solution.Finally brainyoungite is chosen as the cluster connected with GO and the composites meet the requirement.The Cu2+ adsorption capacity of the composite is as high as 1724.1 mg/g.3.Photoluminescence(PL)of GO is quite common and the main range is in the blue-green range.The PL of the brianyoungite-graphene oxide coordination composites is quite different and the main range is in the deep-red range with a quantum yield of about 1%.The PL can be attributed to the optical transition in the disorder-induced localized states.The deep-red photoluminescence may be useful in infrared optoelectronic devices and solar energy exploitation.4.Tungsten sulfide(WS2)can be used in electrochemical hydrogen evolution reaction(HER).The catalytic properties mainly depend on the number of the edge sites.The composite of WS2 and WO3 ·H2O is synthesized by in situ oxidation of tungsten sulfide.In acidic conditions,the proton can be injected into WO3 · H2O and further transferred to the active site of WS2.Therefore,the HER property of the composite is improved.The performance of indium oxide(In2O3)in photoelectrochemical oxygen evolution reaction depends on the proportion of different crystal facets.In2O3 microparticles with different area ratio of the {001} to{111} surface have different photocurrent curves.The results show that holes will accumulate on the {001} facets and the photoelectrochemical performance is proportional to the proportion of {001} facets.Phosphorene will react with oxygen and vapour in the air.This leads to the corrosion of phosphorene and limits the application of phosphorene.In this paper,hydrogenation and then phosphorization is used to mend the surface of the phosphorene which improves the in-air stabitity and the hole mobility.