利用Cd(OH)_2选择性包覆与光分解腐蚀缩小CdS纳米微粒的尺寸分布的研究

提出结合Ｃｄ（ＯＨ）２ 选择性包覆与光分解腐蚀法缩小ＣｄＳ纳米微粒的尺寸分布， 并通过对ＣｄＳ纳米微粒发射光谱的研究证实了这一设计思想． 以多聚磷酸钠（ＨＭＰ）为稳定剂合成ＣｄＳ纳米微粒， 再通过Ｃｄ２＋ 与ＯＨ－ 的选择性包覆在大粒径的ＣｄＳ纳米微粒表面形成一层Ｃｄ（ＯＨ）２， 然后溶液置于日光下辐照处理， 数天后， 未经包覆的小粒径ＣｄＳ纳米微粒被日光腐蚀分解， 溶液中只剩下被Ｃｄ（ＯＨ）２ 包覆的大粒径ＣｄＳ纳米微粒， 这样即可达到缩小ＣｄＳ纳米微粒尺寸分布的目的．

STUDY ON NARROWING THE SIZE DISTRIBUTION OF CdS NANOPARTICLES BY UTILIZING Cd(OH) _2 SELECTIVE COATED AND PHOTOCORROSION

In this paper, a new idea was presented for narrowing the size distribution of CdS nanoparticles by utilizing Cd(OH) 2 selective coated and photocorrosion. At first, CdS nanoparticles were synthesized by wet chemical method. Sodium Hexametaphosphate(HMP) was used as stabilizing agent. Then, a layer of Cd(OH) 2 was deposited on the surface of CdS nanoparticles. According to the theory of curve interface growth kine tics , Cd(OH) 2 prior to grow on the surface of the bigger diameter CdS nanoparticles. So, controlling the amount of OH - and Cd 2+ , the bigger CdS nanoparticles can be selective coated by a layer of Cd(OH) 2. At last, the whole colloid was irradiated by sunlight. CdS nanoparticles can be decomposed under irradiating of sunlight on the condition of oxygen. But Cd(OH) 2, which deposited on the surface of CdS nanoparticles, can prevent the CdS contacting with the oxygen in the water. So, after several days, those uncoated smaller CdS nanoparticles were photocorroded. Only those coated bigger CdS nanoparticles were still in the colloid. Then, the narrowed size distribution of CdS nanoparticles was gained. This idea was confirmed by the study of PL spectrum of CdS nanopaticles. After selective coated by Cd(OH) 2, the CdS nanoparticles' PL spectrum appears two peaks. The peak of high energy comes from the emission of bandedge of coated bigger CdS nanoparticles. The peak of low energy comes from the emission of surface state of uncoated smaller nanoparticles. During the irradiating by sunlight, the peak of the emission of surface state is disappearing gradully. But the peak of the emission of bandedge is still existent.