Shape and surface structure-dependent electrocatalytic activity of Au nanoparticles

Abstract

We describe the shape and surface structure-dependent electrocatalytic activity of chemically synthesized Au nanoparticles of polyhedral, elongated and peanut-like shapes. Au nanoparticles were synthesized by eco-friendly wet chemical route using NADH as a reducing agent. Polyhedral Au nanoparticles were obtained in equimolar solution of Au(III) complex and NADH, involving the disproportionation of in situ generated Au(I) complex. Silver ions felicitate the disproportionation and yields elongated Au nanoparticles. The direct reduction of Au(III) complex to Au(0) in the presence of excess of NADH (1:≥1.5) yields peanut-like Au nanoparticles. The nanoparticles were self-assembled on a sol–gel derived thiol containing silicate network to investigate their electrocatalytic activity. The electrocatalytic performance of the nanoparticles, toward glucose as model system, was examined in neutral and alkaline solution. Shape and surface structure controls the electrocatalytic activity. The polyhedral nanoparticles have pronounced electrocatalytic activity toward glucose and the nanoparticle-based electrode respond linearly from 0.5 to 11 mM. The high electrocatalytic activity of polyhedral nanoparticle is ascribed to its surface structure and morphology. The electrocatalytic activity of elongated and peanut-like nanoparticles is significantly less with respect to the polyhedral nanoparticles. The catalytically active Au(1 1 1) facet of elongated and peanut-like nanoparticles are blocked by the in situ generated AgCl or NAD⁺ during the synthesis.