CdS Nanostructures Self-assembled in the Non-limiting/limiting Condition

Author:Yang Xian De

Supervisor:meng da wei wang yong qian

Database:Doctor

Degree Year:2019

Download:6

Pages:210

Size:19894K

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With the development of industrial civilization,traditional energy is constantly consumed,which resulting in energy crisis.What’s more,the waste discharge also caused pollution of water resources.Therefore,energy crisis and water pollution have become urgent problems to be solved for us.When Japanese scientists found that TiO2can split water to produce H2 and O2 under illumination condition,that makes photocatalytic technology has an important application prospect in the field of solving new kinds of energy and dealing with water pollution.And that promptes more and more research scholars to devote themselves to the development and application of photocatalytic materials.Among them,cadmium sulfide(CdS)as an important direct band gapⅡ-Ⅵsemiconductor material,has cubic zinc-blende phase(2.36 eV)and hexagonal wurtzite phase(2.32 eV)structures.CdS is an important photoelectric material because its absorption in visible light and excellent photoelectric conversion characteristic,and that makes CdS has a widely used in solar cells,light-emitting diodes,sensors,and photoelectric cataltsis.Based on the above research,this paper takes CdS as the research object and studies its application with controllabled assembly under non-limiting and limiting conditions.Firstly,CdS nanostructures with different morphologies were synthesized via hydrothermal method or mixed solvent thermal method through selecting different raw materials,surfactants and other auxiliaries under non-limting condition.And then,their growth mechanisms and photocatalytic degradation of simulation organic pollutants methylene blue were also analyzed.Secondly,in order to improve the photocatalytic performance of CdS,metal ion doping and incorporation with other semiconductors were used to study the modification of CdS.In addition,TiO2 can only absorb ultraviolet light but almost has no absorption of visible light due to its wide band gap.Thus,CdS is also used as a visible photosensitive material to combine with TiO2 to make TiO2 has absorption in visible light and improve the photocatalytic property of TiO2.Finally,combined with the good prospect applications of artificial biomimetic nanochannels in biological molecules,proteins,nucleic acids and ions,CdS nanostructures was controllable self-assembly in limiting condition using AAO nanochannels as artificial biomimetic nanochannels.And then functionalized modifications corresponding biological probes were modified on the surface of CdS to form limited self-assembly detection system with high specificity,high sensitivity.The main research works of this paper are carried out as follows:(1)Flower-like CdS nanostructure with cubic phase was synthesized via hydrothermal method using cadmium chloride,thiurea,ethylenediamine and sodium SDBS as raw materials.When the Cd source was turned into cadmium nitrate,the phase structure of flower-like CdS was mixed phase containing cubic phase and hexagonal phase.The photocatalytic property of mixed phase flower-like CdS was better than that of cubic phase CdS according to UV-Vis,PL results and photocatalytic degradation of methylene blue.(2)Flower-like CdS nanostructure with hexagonal phase was synthesized via hydrothermal method using cadmium nitrate,thiourea and SDBS as raw materials.The morphology of CdS was flower-like structure when SDBS was added,but the morphology of CdS was branch-like without SDBS from FESEM results.The growth mechanism of flower-like CdS was discussed based on the FESEM results.And the photocatalytic performance of branch-like CdS was better than that of flower-like CdS.(3)CdS hollow sphere nanostructures with hexagonal phase was prepared by water/ethylene glycol mixed solvent thermal method using cadmium chloride,sodium thiosulfate and oxialic acid as raw materials.FESEM results showed that the amount of sodium thiosulfate and oxialic acid had significant regulatory effects on the morphology of CdS hollow sphere.On this basis,the growth mechanism of CdS hollow sphere was analyzed.The photocatalytic degradation of methylene blue showed that CdS hollow sphere had good photocatalytic degradation property.(4)Sphere-like CdS with hexagonal phase was synthesized by water/n-butanol mixed solvent thermal method using cadmium chloride,thioacetamide and SDS as raw materials.It is found that the proportion of water:n-butanol affects the surface roughness,while the SDS concentration affects the size of sphere-like CdS from FESEM results.Photocatalytic result showed that sphere-like CdS had good photocatalytic degradation performance for methylene blue.(5)Fishbone-like CdS with hexagonal phase was prepared via hydrothermal method using cadmium chloride and thiourea as raw materials.After different kinds of surfactant such as cationic surfactant CTAB,anionic surfactant SDS,neutral surfactant PEG 2000 was added,it is found that the morphology of CdS was irregular sphere-like structure when surfactant was CTAB,when surfactant was SDS the morphology of CdS was flower-like structure,and the morphology of CdS was irregular branch-like structure while surfactant was PEG 2000.Based on the above results,the growth mechanism of different morphologies was analyzed.Photocatalytic experiment results showed that irregular sphere-like CdS had better photocatalytic degradation performance for methylene blue than that of other morphologies of CdS.(6)Ce3+,Zn2+and Cu2+ions doped CdS nanostructures were synthesized via hydrothermal method in one step using cadmium nitrate,cerium nitrate,zinc nitrate,cupric nitrate and thiourea as raw materials.The influences of metal ion types and concentrations on their morphologies and optical properties were investigated.It is found that metal ion doping can reduce the band gap of CdS according to UV-Vis results,and doping Cu2+can significantly improve the optical performance of CdS,which leading to provide a better photocatalytic degradation property for methylene blue.And the mechanism of ion doping how to improve the photocatalytic property of CdS was also analyzed.(7)Ⅱtype heterojunction composite structure of flower-like CdS/CuS was prepared by hydrothermal method in one step using cadmium nitrate,cupric nitrate and thiourea as raw materials.It is found that the adding order of raw materials affects the morphology of CdS/CuS.UV-Vis results showed that CdS/CuS composite structure had a wide response range of visible light.The photocatalytic H2 evolution results showed that the H2 production rate of CdS/CuS composite structure was higher than that of pure CdS,indicating that the photocatalytic property can be improved by incorporation with other semiconductors.The photocatalytic mechanism of CdS/CuS composite structure was also analyzed.(8)TiO2 NTs was synthesized by anodic oxidation process under titanium sheet substrate,and then CdS nanoparticles were deposited on the surface of TiO2 NTs by SILAR method to form CdS/TiO2 NTs composite structure.UV-Vis results showed that CdS/TiO2 NTs had obvious absorption in visible light due to the component of CdS,which improving the photocatalytic performance of TiO2 NTs.Based on this,the photocatalytic mechanism of CdS/TiO2 NTs composite structure was also explored.(9)AAO template with pore diameter of 110150 nm or 160200 nm was dipped into mixed solution containing cadmium nitrate,thiourea,hexamethylenetetramine via solution impregnation method.The pore diameter of AAO template on flower-like CdS nanostructure self-assembled in limiting condition was discissed.FESEM results showed that AAO template with pore diameter of 160200 nm is suitable for flower-like CdS nanostructure self-assembled in limiting condition.(10)PDA solution was firstly pumped into AAO nanochannels with pore diameter of 4070 nm,and then cadmium nitrate and sodium sulfide solutions were pumped alternately in order to study the assembly density of 0-D CdS nanoparticles in AAO nanochannels under different conditions.On this basis,the-COOH was modified on the surface of CdS and then CEA monoclonal antibody was grafted,which applied to the detection of CEA.The results of I-V curves showed that this system had a good detection on CEA,and the determination rang from 0.1 ng/mL to 100 ng/mL.(11)PDA was firstly pumped into AAO nanochannels with pore diameter of80100 nm,and then AAO template was embedded between two electrolytic chambers with cadmium nitrate and sodium sulfide solutions.CdS nanostructures self-assembled in AAO nanochannels at different conditions was discussed while ions were directional move under electric field.According to this method,CdS nanostructures were self-assembled in AAO nanochannels with pore diameter of 2030 nm,and then L-/D-cysteine was modified and applied to the chiral response transport of bovine serum protein(BSA).At last,theoretical model calculation was used to verify the rationality of the experimental results.