Synthesis of ZnS-CuS-Bi nanonail heterostructures and funnel mechanism of their photocatalytic activity

Abstract

Nanonail shaped ZnS-CuS-Bi three component nanoparticles are synthesized via a simple one-pot colloidal synthesis route by thermal decomposition of metal-thiolate precursors. A thiol serves as the sulfur source and a phase directing capping agent promotes selective anisotropic growth of the nanocrystals in a noncoordinating solvent. After the nucleation and growth of a CuS rod, reactive Cu ions serve as catalytic seeds for the nucleation and growth of ZnS and Bi at the CuS nanorod tips. Thereby the obtained ZnS-CuS-Bi nanocrystals form a chain of two semiconductors of decreasing band gap and a metallic Bi nanoparticle. The three components absorb light in different spectral regions enabling efficient light harvesting. Furthermore, the band edge alignment of ZnS and CuS promote photogenerated electron funneling towards the Bi catalyst particle, which promotes charge carrier separation, effectively channeling the catalytic activity. The photocatalytic performance is assessed at the example of the photodegradation of the organic dye Rhodamine B, and shows excellent performance rendering these nanonails as inexpensive, non-toxic and efficient photocatalyst to remedy environmental pollution.