Electroless deposition of gold nanoparticles on a glassy carbon surface to attain methylene blue degradation via oxygen reduction reactions

A glassy carbon electrode (GCE) surface was modified with gold nanoparticles (Au NPs) via electroless deposition method. It was observed that a pristine GCE surface does not deposit Au NPs through an electroless process. However, while a GCE surface is electrochemically pretreated then sites having negative charges are generated which enables Au (III) particles to be deposited on its surface. The X-ray photoelectron spectroscopy and scanning electron microscopy were used to characterize the electrode surface. It was found that Au NPs are deposited on the GCE surface (Au-GCE) having flower like shapes. The resultant surface was employed to execute electrocatalytic oxygen reduction reactions (ORR). By analyzing hydrodynamic voltammograms, it was confirmed that ORR undergoes a 2e(-) transfer pathway and H2O2 is generated on the Au-GCE surface having a standard rate constant (k(0)) of 5.48 x 10(-9) cm s(-1) at +0.05 V vs. Ag/AgCl (sat. KCl) in 0.1 M H2SO4. The in-situ generated H2O2 can degrade methylene blue (MB) via Electro-Fenton process. The MB degradation was found to match well with the 1st order kinetic model with a homogeneous rate constant of 4.36 x10(-3) min(-1). (C) 2020 Elsevier Ltd. All rights reserved.