Lateral charge propagation effects during the galvanic replacement of electrodeposited MTCNQ (M = Cu, Ag) microstructures with gold and its influence on catalyzed electron transfer reactions

• Isolated MTCNQ (M = Cu, Ag) clusters electrodeposited onto glassy carbon can be galvanically replaced with Au to create MTCNQ/Au composites.
• Lateral charge propagation effects occur which also facilitate decoration of the glassy carbon surface with gold nanoparticles.
• MTCNQ/Au composites are efficient heterogeneous catalysts for the reduction of ferricyanide with thiosulphate ions.
• There is a synergistic effect for CuTCNQ/Au compared to AgTCNQ/Au.

The galvanic replacement of isolated electrodeposited semiconducting CuTCNQ microstructures on a glassy carbon (GC) substrate with gold is investigated. It is found that anisotropic metal nanoparticles are formed which are not solely confined to the redox active sites on the semiconducting materials but are also observed on the GC substrate which occurs via a lateral charge propagation mechanism. We also demonstrate that this galvanic replacement approach can be used for the formation of isolated AgTCNQ/Au microwire composites which occurs via an analogous mechanism. The resultant MTCNQ/Au (M = Cu, Ag) composite materials are characterized by Raman, spectroscopy, X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and investigated for their catalytic properties for the reduction of ferricyanide ions with thiosulphate ions in aqueous solution. Significantly it is demonstrated that gold loading, nanoparticle shape and in particular the MTCNQ–Au interface are important factors that influence the reaction rate. It is shown that there is a synergistic effect at the CuTCNQ/Au composite when compared to AgTCNQ/Au at similar gold loadings.

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