Transformation of zincblende nanoparticles into wurtzite microrods by a dissolution-regrowth process: An intergrowth homojunction with enhanced photocatalytic activity

We report the facile one-pot synthesis of a unique cadmium sulfide (CdS) intergrowth structure in the form of zincblende nanoparticle-decorated wurtzite microrods. The success of this preparation relies on a process involving both dissolution and regrowth. The growth of CdS crystals started from rapid generation of small zincblende nanoparticles, followed by dissolution of some nascent nanoparticles due to the strong alkalinity and relatively high reaction temperature. The resultant CdS monomers, capped by ethanediamine, nucleated again and went through further one-dimensional regrowth, leading to the formation of wurtzite microrods. This transformation gives rise to the generation of a novel intergrowth homojunction that consists of zincblende nanoparticle-decorated wurtzite microrods. Such a close contacted homojunction, having a type-II band alignment, shows an enhanced photocatalytic activity without loading any co-catalyst for solar hydrogen production in comparison to the use of either nanoparticles or microrods alone. This work not only enriches our knowledge on the fundamentals of homojunction formation, but also reveals an important fact that the intergrowth of a rationally designed junction structure shall bring about enhanced photocatalytic activity and thus deserves attention.