Amino-substituted naphthalene sulfonic acid/graphene composite as metal -free catalysts for oxygen reduction reactions

T Getachew,S Admassie,F Addis,T Beyene,S Mehretie

doi:10.4314/bcse.v33i2.16

Abstract

Composites of reduced graphene oxide (rGO) and conducting polymers synthesized from 8-amino-2-naphthalene sulfonic acid (8-ANSA), 5-amino-1-naphthalene sulfonic acid (5-ANSA), 2-amino-1-naphthalene sulfonic acid (2-ANSA), and 4-amino-1-naphthalene sulfonic (4-ANSA) were prepared for use as an electrocatalyst in oxygen reduction reaction (ORR). The electrocatalytic activities were examined in oxygen saturated 0.1 M KOH solution using cyclic and linear sweep voltammetry. The best performing polymer composite was found to be GC/poly(8-ANSA)/rGO, with an enhanced electrocatalytic activity over the rGO only and poly(8-ANSA) only films. More than 100 mV positive shift in the onset potential and 1.6 times increase in current density were observed. The catalytic activity of 2-ANSA, 4-ANSA, 5-ANSA, and 8-ANSA was also validated by density functional theory (DFT). Our calculations predict a much better catalytic activity for 8-ANSA than that of 2-ANSA, 4-ANSA, and 5-ANSA. KEY WORDS : Poly(amino naphthalene sulfonic acid), Reduced graphene oxide, Oxygen reduction reaction, Electrocatalyst Bull. Chem. Soc. Ethiop. 2019 , 33(2), 359-372. DOI: https://dx.doi.org/10.4314/bcse.v33i2.16

Highlights

Oxygen reduction reaction (ORR) is one of the most important reactions in a fuel cell, metal-air batteries, chloroalkali electrolyzer, metal corrosion, sensors, industrial electrolytic process and electro-organic reactions [1,2,3]
Composite films of amino-substituted naphthalene sulfonic acid based polymers and graphene layers were synthesized for metal-free electrocatalyst for oxygen reduction reaction in alkaline media
We applied quantum mechanical (QM) calculations to evaluate the catalytic activity of poly(8amino-2-naphthalene sulfonic acid), poly(2-amino-1-naphthalene sulfonic acid, poly(5-amino-1naphthalene sulfonic acid), and poly(4-amino-1-naphthalene sulfonic acid)

Summary

INTRODUCTION

Oxygen reduction reaction (ORR) is one of the most important reactions in a fuel cell, metal-air batteries, chloroalkali electrolyzer, metal corrosion, sensors, industrial electrolytic process and electro-organic reactions [1,2,3]. Reduced graphene oxide (rGO) sheet shows low dispersibility in solvents and tends to restack as a graphite-like structure due to the removal of most of the oxygen functionalities. Composite films of amino-substituted naphthalene sulfonic acid based polymers and graphene layers were synthesized for metal-free electrocatalyst for oxygen reduction reaction in alkaline media. To the best of our knowledge, graphene oxide composited with amino substituted naphthalene sulfonic acids have never been prepared and examined for electrocatalysis in the oxygen reduction reaction. Amino-substituted naphthalene sulfonic acid/graphene composite as metal-free catalysts 361 electrode (GC) or on polymer modified GC (GC/poly(ANSA)) and was left to dry slowly in air. The natural bond orbital (NBO) analysis [28,29] was used to explore the charges on the atoms before and after the adsorption of the molecular oxygen on the dimers

RESULTS AND DISCUSSION

C8 C10

CONCLUSION