Hexanediamine Monolayer Electrografted at Glassy Carbon Electrodes Enhances Oxygen Reduction Reaction in Aqueous Neutral Media

Hairul Hisham Hamzah,Najahtul Najihah Ahmad Kamal,Turgut Sönmez,Meor Faisal Meor Zulkifli,Shazarizul Haziq Mohd Samsuri,Marta Meneghello,Mohamad Nurul Azmi Mohamad Taib,Saiful Arifin Shafiee

doi:10.1149/1945-7111/abcb77

Abstract

This study presents for the first time the electrocatalytic behaviour of hexanediamine (HDA) monolayer electrografted at glassy carbon (GC) electrodes that enhanced oxygen reduction reaction (ORR) in aqueous neutral media. HDA modified GC electrodes gave a higher current density than platinum bare electrodes based on the cyclic voltammograms (CV), although a ∼0.21 V vs. Ag/AgCl higher onset potential was observed at −0.1 mA cm-2. Electrochemical impedance spectra (EIS) showed that the electrocatalytic reaction on HDA monolayer film towards dissolved oxygen molecules is controlled by diffusion and charge transfer processes. From the scan rate studies and the Laviron equation, it was found that the ORR on this modified electrode proceeded via a fast four-electrons transfer.

Highlights

Electrografting consists of an electrochemical reaction that allows organic layers to bind to a solid conducting surface
Bartlett et al have shown that a stable attachment of engineered enzymes to maleimide-modified multi-walled carbon nanotube (MWCNT) electrodes can be achieved through the electrografting of a primary amine, such as hexanediamine (HDA).[5,10,11]
After the Boc removal, we found that HDA films grafted at GC electrodes remarkably exhibit electrocatalytic activities toward the oxygen reduction reaction (ORR) in 0.1 M potassium chloride (KCl) and phosphate buffer solutions, even in the absence of immobilized enzymes or redox mediators

Summary

Introduction

Electrografting consists of an electrochemical reaction that allows organic layers to bind to a solid conducting surface. After the Boc removal, we found that HDA films grafted at GC electrodes remarkably exhibit electrocatalytic activities toward the ORR in 0.1 M potassium chloride (KCl) and phosphate buffer (pH 7) solutions, even in the absence of immobilized enzymes or redox mediators. This makes the findings reported to be significantly novel in terms of ORR studied in aerated O2 solutions using electrografted primary amines. They were let to dry before conducting the electrochemical characterization

Objectives

Results

Conclusion