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

•Electroless formation of Au nanoparticles to fabricate Au-GCE catalytic surface.•Utilization of Au-GCE catalyst towards electrochemical reduction of oxygen (ORR).•Mechanistic insights regarding the selective formation of H2O2 by ORR on Au-GCE.•Degradation of methylene blue by Electro-Fenton process by in-situ generating reactive oxidative species (ROS). 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 (ko) of 5.48 × 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 ×10−3 min-1. [Display omitted]