Preparation of polyoxometalate stabilized gold nanoparticles and composite assembly with graphene oxide: enhanced electrocatalytic performance

Abstract

Novel polyoxometalate stabilized gold nanoparticles (Au NPs) were prepared by a one-pot procedure in water at room temperature using Pressler-type tungstophosphate (NH₄)₁₄[NaP₅W₃₀O₁₁₀]·31H₂O (P₅W₃₀) as both a reducing and a stabilizing agent. The formation of P₅W₃₀ stabilized Au NPs (Au@P₅W₃₀ NPs) was verified by a comprehensive characterization involving UV-vis spectroscopy, IR spectroscopy, X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction analysis (XRD), dynamic light scattering (DLS) and zeta potential analysis. Afterwards, the composite films of (PDDA/Au@P₅W₃₀/PDDA/GO)₈ (PDDA: polydimethyldiallyl ammonium chloride; GO: graphene oxide) comprising Au@P₅W₃₀ NPs and GO were constructed on ITO-coated glass electrodes and quartz substrates based on a layer-by-layer (LBL) assembly. For comparison purposes, another three composite films of (PDDA/P₅W₃₀)₈, (PDDA/Au@P₅W₃₀)₈ and (PDDA/P₅W₃₀/PDDA/GO)₈ were also fabricated simultaneously on ITO-coated glass electrodes using the same fabrication method. The effects of the composition of four composite films on the electrocatalysis of H₂O₂ reduction were investigated. The results indicated that the tri-component composite film of (PDDA/Au@P₅W₃₀/PDDA/GO)₈ shows enhanced electrocatalytic activity towards the reduction of H₂O₂ due to the synergistic effect of tri-component Au NPs, P₅W₃₀ and GO, large number of active sites and good electron conducting ability originating from GO and the Au NPs.