Facile and green synthesis of graphene oxide by electrical exfoliation of pencil graphite and gold nanoparticle for non-enzymatic simultaneous sensing of ascorbic acid, dopamine and uric acid

Abstract

Pencil graphite is electrochemically exfoliated to obtain few layered graphene oxide (GO) in hydrochloric acid (HCl, HGO), sodium hydroxide (NaOH, NGO) and phosphate buffer saline (PBS, pH 7.4, PGO) media at a constant potential (+7.0 V) without ionic 10 liquid for the first time. Thus, obtained graphene oxide is deposited (by drop casting and electro reduction) onto a glassy carbon electrode (GCE). Following this, gold nanoparticles (AuNP) are electro deposited to form GO-AuNP composite for simultaneous discrimination of dopamine (DA), ascorbic acid (AA) and uric acid (UA) at pH 7.4. Cyclic voltammetry (CV) and differential pulse voltammetry (DPV) techniques reveal well separated oxidation peaks for DA, AA and UA. The sensor surfaces are characterized by Ultraviolet Visible (UV-Vis), Photoluminescence (PL), X-ray diffraction (XRD), Fourier transform Infrared (FTIR), contact angle goniometry (CA) and scanning 15 electron microscopy (SEM) techniques. DA, AA and UA are studied individually to evaluate the dynamic ranges and lowest detection limits of the sensor by the DPV method. Concentrations of DA, AA and UA in real samples viz., dopamine injection, vitamin C tablets and human urine samples are evaluated.

New‐Generation Graphene from Electrochemical Approaches: Production and Applications

“…Graphite anode was detached into 2D fl akes in sodium hydroxide (NaOH) solution by applying a DC potential +7 V, however, the main product was graphene oxide and the overall yield was rather low. [ 29 ] It has been reported that nucleophilic O 2 2− ions, generated from the reaction of H 2 O 2 with hydroxyl ions (HO − ), play an important role in opening graphite edges, breaking the weak interaction between graphene sheets. Exfoliation in a mixed electrolyte (NaOH/H 2 O 2 /H 2 O) led to a high yield (95%) of 3-6 layers of graphene.…”

Au-IDA microelectrodes modified with Au-doped graphene oxide for the simultaneous determination of uric acid and ascorbic acid in urine samples

“…The detection and quantification of UA and AA have been performed by differential pulse voltammetry (DPV) with an electrochemical sensor based on graphene oxide modified with gold nanoparticles, achieving limit of detection (LOD) of 20 M and 200 M, respectively [22]. However, the LOD obtained for AA should be improved due to the fact that levels of AA in plasma for healthy people are usually lower [7,8] and the detection of concentrations lower than 20 M is also interesting [8,23].…”

Self‐powered polymer–metal oxide hybrid solar cell for non‐enzymatic potentiometric sensing of bilirubin

“…At this time, the blocking layer NZP maximizes the photo processes and enhances the oxidation by injecting the electrons concurrently in the conduction band, which in turn increases the OCP potential. This potential is quite closer to oxygen evolution reaction of metal oxides and, hence, kinetically drives the reaction E sp = 303[BL] + 0.452 (Imran, Manikandan, & Dharuman, ). That is, BR oxidation generates electrons which is biased to cathode (n‐Al–ZnO), whereas the holes biased to p‐PANI/PVA and sustains the detection voltage at 0.832 V. Activities of bilirubin reactions at the solar‐powered sensor surfaces depend on the solution pH, and therefore, effect of solution pHs on the catalytic activity is examined, Figure a.…”