Modulated Triple‐Material Nano‐Heterostructures: Where Gold Influenced the Chemical Activity of Silver in Nanocrystals. Issue 33 (19th July 2018)

• Record Type: Journal Article
• Authors: Sahu, Puspanjali; Prusty, Gyanaranjan; Guria, Amit K.; Pradhan, Narayan
• Is Part Of: Small. Volume 14:Issue 33(2018)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2018-07-19
• Subjects: bimetallic‐binary alloy‐binary/ternary semiconductors -- diffusion -- heterostructures -- ion exchange; Nanotechnology -- Periodicals; Nanoparticles -- Periodicals; Microtechnology -- Periodicals; 620.5
• DOI: 10.1002/smll.201801598
• Languages: English
• ISSNs: 1613-6810

Abstract

Abstract: For efficient charge separations, multimaterial hetero‐nanostructures are being extensively studied as photocatalysts. While materials with one heterojunction are widely established, the chemistry of formation of multijunction heterostructures is not explored. This needs a more sophisticated approach and modulations. To achieve these, a generic multistep seed mediated growth following controlled ion diffusion and ion exchange is reported which successfully leads to triple‐material hetero‐nanostructures with bimetallic‐binary alloy‐binary/ternary semiconductors arrangements. Ag2 S nanocrystals are used as primary seeds for obtaining AuAg‐AuAgS bimetallic‐binary alloyed metal–semiconductor heterostructures via partial reduction of Ag(I) using Au(III) ions. These are again explored as secondary seeds for obtaining a series of triple‐materials heterostructures, AuAg‐AuAgS‐CdS (or ZnS or AgInS2 ), with introduction of different divalent and trivalent ions. Chemistry of each step of the gold ion–induced changes in the rate of diffusion and/or ion exchanges are investigated and the formation mechanism for these nearly monodisperse triple material heterostructures are proposed. Reactions without gold are also performed, and the change in the reaction chemistry and growth mechanism in presence of Au is also discussed. Abstract : Modulated triple material heterostructures of alloyed metal and binary‐ternary semiconductors are fabricated via Au(I) assisted controlled diffusion in seed Ag2 S nanocrystals. Using Zn(II), Cd(II), In(III), and Ga(III) precursors, triple material heterostructures are designed. Here, Au is found to suppress complete ion exchange, slow down diffusion of foreign ions, and retains with Ag(0) and Ag(I) in the heterostructure domains.