Electrochemical ascorbic acid sensor based on DMF-exfoliated graphene

Abstract

This paper describes the electron transfer properties of graphene nano-sheets (GNSs) immobilised on pyrolysed photoresist film (PPF) electrodes. The former are produced by the dispersion and exfoliation of graphite in dimethylformamide, and they are characterised using transmission electron microscopy, scanning electron microscopy and Raman spectroscopy. Cyclic voltammetry and electrochemical impedance spectroscopy are used to quantify the effect of the GNSs on electrochemical surface area and on electron transfer kinetics. Compelling evidence is reported in relation to the importance of edgeplane sites and defects in the promotion of electron transfer at carbon nanostructures. A novel ascorbic acid (vitamin C) sensor is presented based on the PPF/GNS system, which is effective in the range 0.4 to 6.0 mM, with a 0.12 mM detection limit. The selectivity of the sensor is demonstrated using a commercially available vitamin C supplement. This is the first report of the electrochemical properties of graphene nano-sheets produced using liquid-phase exfoliation, and it will serve as an important benchmark in the development of inexpensive graphene-based electrodes with high surface area and electro-catalytic activity.

Scalable production of large quantities of defect-free few-layer graphene by shear exfoliation in liquids

“…However, such methodologies just shift the rate-limiting step from exfoliation to intercalation, limiting the potential for scale-up. What would be more useful would be if untreated layered crystals 4 could be exfoliated in liquids using only shear mixing. This would allow the application of the well-known strategies for the scale-up of shear mixing processes that are commonly used in industry.…”

“…1 Some important classes of applications, such as printed electronics, conductive coatings and composite fillers, will require industrial-scale production of defect-free graphene in a processable form. For example, graphene is likely to be used as a low-cost electrode material in applications such as solar cells, 2 batteries 3 and sensors 4 . Such electrodes will almost certainly be produced by solution-coating and so will require large quantities of graphene in the form of liquid suspensions, inks or dispersions 1 .…”

Few-layer graphene sheets with embedded gold nanoparticles for electrochemical analysis of adenine

“…Linear sweep voltammetry analysis was conducted using an Autolab 302N potentiostat/galvanostat (Eco Chemie, Utrecht, The Netherlands) connected to a three-electrode cell and controlled by Nova 1.8 software. The surface area of the working electrode was 0.07 cm 2 ; as a counter, we used a platinum electrode with a larger area (approximately 2 cm 2 ). The reference was an Ag/AgCl electrode.…”

“…[1][2][3] As a result of its large surface area and the high mobility of its charge carriers (200,000 cm 2 /V/sec), 4 graphene enhances the electron transfer process. In addition, its two-dimensional structure is an extremely attractive support for the attachment of metal nanoparticles.…”

Progress in Imidazolium Ionic Liquids Assisted Fabrication of Carbon Nanotube and Graphene Polymer Composites

“…The second methodology is to directly exfoliate graphite into less defective (or defect-free) single-or few-layer graphene sheets in suitable solvents by means of ultrasonic energy, microwave irradiation or other techniques. It has been reported that the solvent-exfoliated graphene dispersions can be produced by direct exfoliation of graphite in organic solvents such as DMF [86,91,92], NMP [93,94], ODCB [95] and surfactant/water solutions [96] or supercritical fluids [97]. However, the maximum concentration of graphene sheets achieved is still low (<1 mg·mL −1 ) and can only increases to 2 mg·mL −1 by a low-power sonication regime over long time frames (460 h) [94].…”