Growth–regime–controlled synthesis of CdS–Bi2S3 and Bi2S3 nanocrystals during the dissolution–recrystallization processes

Inorganic composite nanocrystals have been widely investigated due to their novel properties and potential applications. However, to date, more effort is needed to suppress the homogeneous nucleation and self–growth of the second–component nanocrystals. In our work, we have introduced Bi3+ ions which can react with the CdS mother nanocrystals (NCs) during the dissolution processes of the mother NCs. Subsequently, the nanocrystals which recrystallize on the surfaces of the CdS mother nanocrystals are Bi2S3 nanocrystals rather than the mother ones due to the lower solubility of Bi2S3. Therefore, it is effective to avoid separation between the CdS mother nanocrystals and the second–component Bi2S3 nanocrystals. During this dissolution–recrystallization process, the growth regime can be facilely controlled from the thermodynamic control to the kinetic domination through adding more Bi3+ ions or changing the heating method from an oil bath to a microwave field. Consequently, the obtained CdS–Bi2S3 composite nanostructures can evolve from core–shell to tangentially–bonded structures in the oil bath, while tangentially–bonded CdS–Bi2S3 composite NCs and nest–shaped Bi2S3 NCs can be achieved in the microwave field.