Fabrication and electrochemical response of pristine graphene ultramicroelectrodes

Ultramicroelectrodes (UMEs) are electrochemical working electrodes with at least one dimension less than 25 μm. Here, we demonstrate a method to fabricate pristine (contamination and doping-free) monolayer graphene UMEs characterise its properties. Graphene is particularly sensitive both contamination from device fabrication doping the substrate, these effects detrimental accurate measurements of fundamental properties as well electrode applications. We UME design steps which ensure that electro-active surface never comes into contact contaminants such process polymers solvents, has well-defined area due self-aligned fabrication, shield converse side highly inert dielectric hexagonal boron nitride (h-BN). Cyclic voltammetry demonstrates expected steady-state behaviour for in hemispherical diffusion regime. The reduction IrCl62− weak KCl electrolytes was employed investigate electron transfer characteristics reproducibility measurements. Values standard rate constant, k0 coefficient, α were measured be 3.04 ± 0.78 × 10−3 cm s−1 0.272 0.024 respectively. These values consistent reduced charge substrate. This further confirmed by Raman spectroscopy before after