The electrochemical performance of graphene modified electrodes: An analytical perspective† Dale A. C. Brownson, Christopher W. Foster and Craig E. Banks * Received 20th December 2011, Accepted 17th February 2012 DOI: 10.1039/c2an16279b We explore the use of graphene modified electrodes towards the electroanalytical sensing of various analytes, namely dopamine hydrochloride, uric acid, acetaminophen and p-benzoquinone via cyclic voltammetry. In line with literature methodologies and to investigate the full-implications of employing graphene in this electrochemical context, we modify electrode substrates that exhibit either fast or slow electron transfer kinetics (edge- or basal- plane pyrolytic graphite electrodes respectively) with well characterised commercially available graphene that has not been chemically treated, is free from surfactants and as a result of its fabrication has an extremely low oxygen content, allowing the true electroanalytical applicability of graphene to be properly de-convoluted and determined. In comparison to the unmodified underlying electrode substrates (constructed from graphite), we find that graphene exhibits a reduced analytical performance in terms of sensitivity, linearity and observed detection limits towards each of the various analytes studied within. Owing to graphene’s structural composition, low proportion of edge plane sites and consequent slow heterogeneous electron transfer rates, there appears to be no advantages, for the analytes studied here, of employing graphene in this electroanalytical context. Introduction Graphene continues to receive a substantial degree of interest from a plethora of scientific disciplines, 1,2 and consequently global efforts to investigate and exploit graphene’s unique and exceptional properties have resulted in numerous advantageous and innovative applications being realised for the first time. 2,3 Of particular interest is the exploration of graphene’s electro- chemical properties and resultant applications, 4–8 where it has been reported to exhibit wide potential applicability as an effective electrode material within the fabrication of various analytical and energy related devices. 4–8 Most notably, graphene has been reported to be utilised as an enhanced sensor substrate in terms of the improved electroana- lytical monitoring of various substances, which is of substantial interest and importance depending upon the variable toxicity and nature of the analyte studied. 4–6 Owing to its reported advantageous properties, graphene has thus been utilised in the development and exploration of fast, sensitive and reliable detection methods for a range of target analytes, for instance towards the detection of ascorbic acid, 9 glucose, 10 hydrazine, 11 hydrogen peroxide 12 and nitric oxide, 13 where upon comparison to the performance of the more traditional noble metal and various other fullerene based alternatives, graphene is currently portrayed as a highly beneficial and superior electrode material. 4–6 Considering such reports, future electrochemical prospects for graphene appear promising; note however, reports have emerged indicating that a tentative approach must be employed when utilising graphene. 14–16 For example we have previously shown that surfactants, which are routinely incorporated into the fabrication of commercially available graphene to reduce the likelihood of the graphene sheets coalescing, both beneficially and detrimentally interfere and significantly contribute towards the observed electrochemical response of graphene towards the sensing of different analytes. 14,15 Such work indicated for the first time that appropriate control experiments need to be employed before the beneficial electrochemistry of graphene can be correctly reported and are thus required in order to sufficiently de-convolute the true performance of graphene. In this paper we explore the analytical perspectives of gra- phene modified electrodes utilising commercially available gra- phene which is well characterised, completely free from surfactants and has not been purposely oxidised or treated. We compare and critically contrast the electroanalytical perfor- mance of graphene modified edge- and basal- plane pyrolytic graphite electrodes (EPPG and BPPG respectively) constructed Faculty of Science and Engineering, School of Science and the Environment, Division of Chemistry and Environmental Science, Manchester Metropolitan University, Chester Street, Manchester M1 5GD, Lancs, UK. E-mail: c.banks@mmu.ac.uk; Web: www. craigbanksresearch.com. Fax: ++(0)1612476831; Tel: ++(0)1612471196 † Electronic supplementary information (ESI) available. See DOI: 10.1039/c2an16279b This journal is ª The Royal Society of Chemistry 2012 Analyst, 2012, 137, 1815–1823 | 1815 Dynamic Article Links C < Analyst Cite this: Analyst, 2012, 137, 1815 www.rsc.org/analyst PAPER