Nonenzymatic h2o2 sensing using graphene-ag nanoparticle hybrid

Maryam Rezaei,1,* A. nekahi ,2 M.a. mohammadmirzaie ,3

1. Chemical and polymer engineering group, Yazd University, Yazd, Iran
2. Nanostructure coating institute, Yazd PayameNoor University, Yazd, Iran
3. Chemical and polymer engineering group, Yazd University, Yazd, Iran

Abstract

Introduction

there is a great demand for sensitive, reliable, low-cost and small electrochemical biosensors for detection of different kinds of biomarkers such as hydrogen peroxide. the sensitivity and selectivity of biosensors strongly depend on the modified electrode surface. these characteristics have been improved using graphene nanostructures with intrinsically high surface area and reactivity. graphene hybrids with other nanomaterials have shown improved electrochemical and sensing performance due to their catalytic activity. ag nps have been attracted as hybrid material for h2o2 sensing regarding electrocatalysis, anti-bacterial property and nontoxicity. the nps prevent the accumulation and agglomeration of graphene sheets [1-3]. the combination of extreme surface area and reactivity of graphene and catalytic characteristic of agnps can improve sensing performance of the electrode even in the nonenzymatic electrochemical sensors

Methods

2.1. graphene‒agnws hybrid go was prepared by modified hummers method [4]. agnps were obtained from acsnano. a mixture of graphene oxide (1.5 mg.ml-1) and nps (1 mg) was poured in an autoclave nd then was placed in an oven at 180 °c for 18 h. the produced aerogel was freeze dried at -80 °c. 2.2. electrochemical analysis sensor electrode was prepared using gf-agnps hybrid on ag paste. amperometric test and impedance spectroscopy were carried out in a 3-electrode system containing calomel reference electrode, an ag wire as counter electrode and hybrid working electrode. while the former was performed in 0.1 m ph 7 phosphate buffer solution (pbs) and the latter was done in k3fecn6.

Results

The hybrid morphology is depicted in the sem micrograph in fig. 1. it is obvious that a 3-d porous structure with an open network was formed in the hydrothermal synthesis of gf. this structure certainly provides a huge specific surface area and more active sites for electrolyte diffusion comparing graphene sheets. fig. 1 reveals that during hydrothermal synthesis of graphene foam, agnps were finely dispersed between different layers and cavities lead to a homogenous gf-agnps hybrid. fig. 1- sem of gf-agnps hybrid structure with fine distribution. the electrochemical impedance spectroscopy (eis) was applied to investigate the ion-transport behavior and electrical resistance of the electrodes, as shown in fig. 2. commonly, eis data of biosensing electrodes have revealed a semicircle indicative of the charge-transfer resistance on the electrode surface and a 45 ° line showing diffusion. as it can be seen in fig. 2, there is no semicircle and it is a sign of high conductivity of the electrode. fig. 2- eis spectra of gf-agnps hybrid electrode in pbs. the electrode was also used for h2o2 sensing, fig. 3. cv plots show that cathodic peak moved to more negative potentials by addition the concentration of h2o2. moreover, the cathodic peak current increased as a result of h2o2 electrochemical reaction on the electrode surface. therefore, hydrogen peroxide was sensed significantly by the electrode. fig. 3- cv of sensing different concentrations of h2o2.

Conclusion

In this research, gf-agnps hybrid was used for sensing h2o2. eis results confirmed high electrical conductivity of the electrode surface. in addition, cv analysis revealed high electrochemical performance in h2o2 sensing. the simple electrode can be used for biosensing applications.

Keywords

Nanobiosensor; ag nanoparticles (agnps); graphene; hybrid; hydrogen peroxide.