DOI: 10.1002/elan.201300363 Electroanalytical Performance of a Freestanding Three-Dimensional Graphene Foam Electrode Luiz C. S. Figueiredo-Filho, [a] Dale A. C. Brownson, [b] Orlando Fatibello-Filho, [a] and Craig E. Banks* [b] 1 Introduction The design and synthesis of analytical sensing systems is of global interest and thus research into fabricating new- generation analytical sensors is a highly diverse and dy- namic field [1, 2]. As a result of this immense interest a plethora of sensing devices are continually being devel- oped, with applications being realised in the fields of clin- ical, industrial and environmental analysis [3]. Of particu- lar interest are electrochemically derived sensors which attract attention due to their ability to convert chemical information into an electrical signal and through careful design can give rise to sensitive, selective, experimentally simple and low cost sensors [1–3]. In order to enhance the analytical capabilities of elec- trochemical based sensors, electrochemists are continu- ously searching for new electrode materials that possess both improved and advantageous properties in compari- son to the more traditional and commonly employed elec- trode materials, namely noble metals and graphite [4]. In- terest in carbon based electrode materials has thrived in recent years with the emergence of carbon nanomaterials offering beneficial electrochemical properties and result- ing in numerous opportunities to design and implement improved and novel sensors [5]. One particular nanoma- terial that is no exception to this trend is graphene, which is potentially one of the world)s thinnest electrode materi- als, with its two-dimensional (2D) lattice comprising a monolayer of hexagonally configured sp 2 hybridised carbon atoms [2]. Graphene is reported to possess a unique array of spectacular physical, chemical and ther- mal properties [2, 5–7] and as a result has been widely ex- plored as an electrode material [2, 8]. Significant attention has focused on the exploration and exploitation of gra- phene as an enhanced sensor substrate, where it has been reported to exhibit beneficial electroanalytical perform- ances towards, for example, the sensing of cadmium, dop- amine, hydrogen peroxide and serotonin, to name just a few [5, 6, 9–11]. The application of graphene within electrochemistry has clear potential to revolutionise this field [2]. Howev- er, there are certain experimental challenges that need to be overcome before graphene can be effectively utilised as an electrode material: first there is the problem of how to electrically wire/connect to such a material and usually approaches involve a top-down fabrication method; the second important consideration is how to reduce the ag- gregation of graphene sheets back to their lowest energy confirmation, that is, graphite, due to the strong p p in- teractions between the graphene sheets [2, 12]. One ex- perimental answer to these problems is to introduce the concept of a 3D graphene structure, such as a 3D gra- phene foam which possesses a porous macrostructure with microscopic graphene features [12]. Such graphene Abstract : The electroanalytical performance of a free- standing three-dimensional (3D) quasi-graphene macro- structure is evaluated and benchmarked towards model analytes in aqueous solutions. Due to the freestanding 3D graphene foam exhibiting near-super-hydrophobicity and consequently giving rise to poor voltammetric signatures in aqueous solutions (Brownson et al., J. Mater. Chem. A, 2013, 1, 5962), we explore a (washing) pretreatment pro- cedure to reduce the hydrophobic behaviour of the 3D graphene macrostructure in order to try and allow its ef- fective application in such cases. Herein, the electrochem- ical properties and resultant electroanalytical perfor- mance of the pretreated 3D graphene foam (3D-GF) is critically explored and compared to a freestanding 3D re- ticulated vitreous carbon (3D-RVC) foam alternative to- wards the sensing of a range of important analytes via cyclic voltammetry in aqueous solutions; namely, uric acid (UA), acetaminophen (AP) and dopamine hydro- chloride (DA). It is found that the 3D-RVC exhibits im- proved electroanalytical characteristics with larger linear ranges and lower limit of detections achievable over that of the 3D-GF towards the target analytes. This work pro- vides a vital insight into electroanalysis using 3D gra- phene and carbon foams. Keywords: Graphene electrochemistry · Three-dimensional electrode · Free-standing graphene foam · Electron transfer · Sensing [a] L. C. S. Figueiredo-Filho, + O. Fatibello-Filho Departamento de Química, Universidade Federal de S¼o Carlos, S¼o Carlos - SP, Brazil, P.O. Box 676, 13560-970 [b] D. A. C. Brownson, C. E. Banks 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 tel: ++ (0)1612471196; fax: ++ (0)1612476831 Website: www.craigbanksresearch.com *e-mail: c.banks@mmu.ac.uk [ + ] Visiting student Special Issue GRAPHENE www.electroanalysis.wiley-vch.de  2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim Electroanalysis 2014, 26, 93 – 102 93 Full Paper