Tyramine Functionalized Graphene: Metal‐Free Electrochemical Non‐Enzymatic Biosensing of Hydrogen Peroxide

Abstract

We report here non‐enzymatic electrochemical biosensing of H2O2 using a highly stable, metal‐free, tyramine functionalized graphene (T‐GO) based electrocatalytic system. The surface functionalization of tyramine on graphene was carried out chemically. The obtained sheets were characterized by scanning electron microscopy (SEM), X‐ray diffraction (XRD) as well as X‐ray photoelectron (XP), Raman, FT‐IR and UV‐visible spectroscopy. More significantly, the combined results from morphological and structural studies show the formation of a few layers of graphene with effective large‐scale functionalization by tyramine. As a metal‐free electrocatalyst, the as‐synthesized T‐GO shown good electrocatalytic activity towards reduction of H2O2 with a sensitivity of 0.105 mM/cm2 confirmed by combined results from cyclic voltammetric (CV) and linear sweep voltammetric (LSV), and amperometric (i–t) measurements. The lower onset potential (−0.23 mV vs SCE), lower detection limit, wider concentration range (10 mM to 60 mM) with higher electrochemical current and potential stability demonstrated the potential of our non‐enzymatic and cost‐effective T‐GO based electrocatalytic system towards reduction of hydrogen peroxide.

Graphitic Carbon Nitride (g‐C3N4) Nanosheets as a Multipurpose Material for Detection of Amines and Solar‐Driven Hydrogen Production

“…Additionally, the O 1s spectrum of CN−KNa was further analyzed to reveal O atoms′ oxidation states (Figure S.2). The signal can be deconvoluted into three individual peaks at a binding energy of 530.9, 532.5, and 535.1 eV, which can be attributed to oxygen in the form of C=O, C−O, and C−OH bonds, respectively [37] . These results are in good agreement with the respective C 1s and N 1s XPS results that confirm the occurrence of oxygen‐containing functional groups on the CN−KNa sample.…”

“…Notably, a distinct peak at 401.3 eV was recognized from the N 1s XPS signal of CN−KNa. This weak peak point out the presence of sp 2 N atoms bonded with sp 2 hybridized C neighbours (NH−C=O), [37] which might be due to the carbonyl group‘s formation CN−KNa sample. Additionally, the O 1s spectrum of CN−KNa was further analyzed to reveal O atoms′ oxidation states (Figure S.2).…”

Enhanced Electrochemical NO2−Oxidation Reactions on Biomolecule Functionalised Graphene Oxide

“…The downfield shifting of (002) plane is due to the amine functionalization present in GT over GO and is in good agreement with earlier findings. [35] Moreover, the diffraction pattern shows a peak at 2θ = 26.7 corresponding to graphene like nature, hence, it confirms the formation of GO is of high purity and homogeneous functionalization of tyramine is done successfully. To support this analysis shown in Figure S3.…”

“…Superimposed FTIR spectra of GO and GT are shown in Figure 3(a) represents a peak at 3440 cm −1 corresponding to O−H stretching frequency for water molecules (adsorbed) and associated with carboxylic acid and hydroxyl functional groups. Then, the presence of other functional groups on the surface of GO are also confirmed, for example, C=O, C=C, C−O, and C−H bond stretching bands at 1715 cm −1 , 1640 cm −1 , 1105–1400 cm −1 and 2920 cm −1 respectively corresponding to carbon skeleton and oxidative functionalities available on the surface of GO [35,36] . Then, surface modification of GO with tyramine, whereas the intensities of hydroxyl (−OH) and carbonyl (C=O) stretching bands decreased, and the new amine‐based stretching bands is observed at 1580 cm −1 corresponding to tyramine functionalization.…”

“…Then, the presence of other functional groups on the surface of GO are also confirmed, for example, C=O, C=C, CÀ O, and CÀ H bond stretching bands at 1715 cm À 1 , 1640 cm À 1 , 1105-1400 cm À 1 and 2920 cm À 1 respectively corresponding to carbon skeleton and oxidative functionalities available on the surface of GO. [35,36] Then, surface modification of GO with tyramine, whereas the intensities of hydroxyl (À OH) and carbonyl (C=O) stretching bands decreased, and the new amine-based stretching bands is observed at 1580 cm À 1 corresponding to tyramine functionalization. Furthermore, Raman spectra for GO and GT which is a non-destructive method to describe the nature and structure of carbon based materials.…”