Fabrication and Characterisation of Graphene and its use in Formation of Graphene Ring Microelectrodes (GRiMEs)

摘要

We report the fabrication, characterisation and use of graphene for the fabrication of Graphene Ring Microelectrodes (GRiMEs). Graphene was fabricated using a modified Hummers method and optimised hydrazine-thermal reduction procedure. So-formed graphene was characterised using measurement of light transmittance, sheet resistivity, droplet contact angle and AFM. GRiMEs were formed by dip coating fibre optics with GO followed by reduction to graphene. The behavior of the so-formed GRiMEs was studied using the probe redox system ferricyanide and electrode thicknesses assessed by physical methods using AFM operating in contact, lateral force and current sensing modes. Using 220 μm dia. fibre optics, ring electrode thicknesses ranging from 73.8 nm - 18 nm were obtained. The fabricated GRiMEs are highly reliable (ⅰ-ⅴ response invariant over ＞300 scans), the microring design allowing for efficient use of electrochemically active graphene edge sites. Further, the associated nA scale currents neatly obviate issues relating to the high resistivity of undoped graphene. Thus, the use of graphene in ring microelectrodes improves the reliability of existing microelectrode designs and expands the range of use of graphene-based electrochemical devices.