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Herein we review the use of electrochemical point-of-care SPE-based sensor technologies towards the detection of vital, established biomarkers related to cardiac injury, cancer diagnostics and acute inflammatory conditions.

Screen-printed electrodes (SPEs) are ubiquitous within the field of electrochemistry and are commonplace within the arsenal of electrochemists. Their popularity stems from their reproducibility, versatility, and extremely low-cost production, allowing their utilization as single-shot electrodes and thus removing the need for tedious electrode pretreatments. Many SPE studies have explored changing the working electrode composition and/or size to benefit the researcher's specific applications. In this paper, we explore a critical parameter of SPEs that is often overlooked; namely, we explore changing the length of the SPE connections. We provide evidence of resistance changes through altering the connection length to the working electrode through theoretical calculations, multimeter measurements, and electrochemical impedance spectroscopy (EIS). We demonstrate that changing the physical length of SPE connections gives rise to more accurate heterogeneous electrode kinetics, which cannot be overcome simply through IR compensation. Significant improvements are observed when utilized as the basis of electrochemical sensing platforms for sodium nitrite, β-nicotinamide adenine dinucleotide (NADH), and lead (II). This work has a significant impact upon the field of SPEs and highlights the need for researchers to characterize and define their specific electrode performance. Without such fundamental characterization as the length and resistance of the SPE used, direct comparisons between two different systems for similar applications are obsolete. We therefore suggest that, when using SPEs in the future, experimentalists report the length of the working electrode connection alongside the measured resistance (multimeter or EIS) to facilitate this standardization across the field.

2D hexagonal boron nitride (2D-hBN) is a lesser utilised material than other 2D counterparts in electrochemistry due to initial reports of it being non-conductive. As we will demonstrate in this review, this common misconception is being challenged, and researchers are starting to utilise 2D-hBN in the field of electrochemistry, particularly as the basis of electroanalytical sensing platforms. In this critical review, we overview the use of 2D-hBN as an electroanalytical sensing platform summarising recent developments and trends and highlight future developments of this interesting, often overlooked, 2D material.

Monolayer hexagonal-boron nitride films (2D-hBN) are typically reported within the literature to be electrochemically inactive due to their considerable band gap (ca. 5.2–5.8 eV). It is demonstrated herein that introducing physical linear defects (PLDs) upon the basal plane surface of 2D-hBN gives rise to electrochemically useful signatures. The reason for this transformation from insulator to semiconductor (inferred from physicochemical and computational characterisation) is likely due to full hydrogenation and oxygen passivation of the boron and/or nitrogen at edge sites. This results in a decrease in the band gap (from ca. 6.11 to 2.36/2.84 eV; theoretical calculated values, for the fully hydrogenated oxygen passivation at the N or B respectively). The 2D-hBN films are shown to be tailored through the introduction of PLDs, with the electrochemical behaviour dependent upon the surface coverage of edge plane-sites/defects, which is correlated with electrochemical performance towards redox probes (hexaammineruthenium(III) chloride and Fe2+/3+) and the hydrogen evolution reaction. This manuscript de-convolutes, for the first time, the fundamental electron transfer properties of 2D-hBN, demonstrating that through implementation of PLDs, one can beneficially tailor the electrochemical properties of this nanomaterial.

In 2020, the new European Drinking Water Directive will be updated to include new drinking-water safety parameters. These will introduce reduced thresholds for the presence of heavy metals, pesticides and other contaminants in domestic drinking water. The aim of these reduced thresholds is to impose a higher level of consumer protection as well as provide guidance for effective monitoring, planning and water management. An example of a newly proposed threshold is the concentration of lead ions (Pb2+) within drinking water, which has been reduced from 10 to 5 parts per billion (ppb). The strict timeframe for water suppliers to meet the new thresholds has created an impetus to develop in situ detection techniques to quantify the levels of chemical contamination on-site in drinking water, allowing them to make prompt interventions. This review explores and discusses the current advances related to electrochemical methods, electrode materials and modifications that have the potential to be the foundations of a new generation of portable electrochemical sensors towards trace-level ion in situ heavy metal sensors.

We report the electroanalytical properties of graphene and graphite paste electrodes comprising varying lateral flake sizes. The fabricated electrodes are first electrochemically validated using a standard redox probe prior to the influence of their heterogeneous electron transfer (HET) kinetics/flake sizes being explored towards sensing applications. Electrochemical analysis is employed using a range of relevant biomolecules and prominent drugs of abuse. It is inferred that smaller lateral flake sizes result in an increased number of edge plane sites ‘available’ upon the electrode surface, leading to greater sensitivity and Limit of Detection (LOD) values. Calibration plots show an improvement in LODs from 0.7 to 0.19 μM and sensitivity from 0.023 to 0.038 A M−1 for the detection of ascorbic acid and LODs from 3.43 to 1.3 μM and sensitivities from 0.009 to 0.025 A M−1 for the detection of β-nicotinamide adenine dinucleotide (NADH) when comparing ‘typical’ (12.2 μm) and ‘small’ (0.5 μm) lateral flake sizes. In the case of uric acid, the reported sensitivity and LOD with typical sizes is 0.046 A M−1 and 1.42 μM, in comparison to 0.168 A M−1 and 0.85 μM with smaller flakes, with dopamine also supporting these findings. In terms of the drugs of abuse considered, methamphetamine exhibits an improved LOD from 0.82 to 0.65 μg mL−1 and sensitivity from 0.15 to 0.25 A μg mL−1 when comparing typical and small flakes respectively. However, cocaine and 3,4-methylenedioxymethamphetamine (MDMA) exhibit variable results, likely due to complex oxidation mechanisms and each paste electrode's specific heterogeneous surface nature. This work demonstrates the sensing capabilities of graphene and graphite paste electrodes comprising varying lateral flake sizes. It is inferred that smaller lateral flake sizes give rise to improved electroanalytical responses and enhanced graphitic based electrochemical sensors; which is important to consider when designing and optimising carbon based electrochemical sensor devices and likely has wider implications in the energy sector when utilising such electrodes.

Robust, reliable, and affordable analytical techniques are essential for screening and monitoring food and water safety from contaminants, pathogens, and allergens that might be harmful upon consumption. Recent advances in decentralised, miniaturised, and rapid tests for health and environmental monitoring can provide an alternative solution to the classic laboratory-based analytical techniques currently utilised. Electrochemical biosensors offer a promising option as portable sensing platforms to expedite the transition from laboratory benchtop to on-site analysis. A plethora of electroanalytical sensor platforms have been produced for the detection of small molecules, proteins, and microorganisms vital to ensuring food and drink safety. These utilise various recognition systems, from direct electrochemical redox processes to biological recognition elements such as antibodies, enzymes, and aptamers; however, further exploration needs to be carried out, with many systems requiring validation against standard benchtop laboratory-based techniques to offer increased confidence in the sensing platforms. This short review demonstrates that electroanalytical biosensors already offer a sensitive, fast, and low-cost sensor platform for food and drink safety monitoring. With continued research into the development of these sensors, increased confidence in the safety of food and drink products for manufacturers, policy makers, and end users will result.

© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim We demonstrate that polylactic acid (PLA)/graphene additive manufactured (3D-printed) electrodes (Gr/AMEs) electrodeposited with Ni−Fe (oxy)hydroxide can efficiently catalyse the oxygen evolution reaction (OER). X-ray photoelectron spectroscopy (XPS) depth profiling combined with Atomic Force Microscopy (AFM) and Tip Enhanced Raman Spectroscopy (TERS) deduced the composition and depth of the Ni−Fe (oxy)hydroxide layer. The composition of the resulting electrocatalytic surfaces are tailored through altering the concentrations of nickel and iron within the electrodeposited solutions, which give rise to optimised AMEs OER performance (within 0.1 M KOH). The optimal OER performance was observed from a Ni−Fe (oxy)hydroxide with a 10 % content of Fe, which displayed an OER onset potential and overpotential of+1.47 V (vs. RHE) and 519 mV, respectively. These values arecomparable to that of polycrystalline Iridium (+ 1.43 V (vs. RHE) and ca. 413 mV), as well as being significantly less electropositive than a bare/unmodified AME. This work is essential for those designing, fabricating and modulating additive manufactured electrodes.

Mono-, few-, and multilayer graphene is explored towards the electrochemical Hydrogen Evolution Reaction (HER). Careful physicochemical characterisation is undertaken during electrochemical perturbation revealing that the integrity of graphene is structurally compromised. Electrochemical perturbation, in the form of electrochemical potential scanning (linear sweep voltammetry), as induced when exploring the HER using monolayer graphene, creates defects upon the basal plane surface that increases the coverage of edge plane sites/defects resulting in an increase in the electrochemical reversibility of the HER process. This process of improved HER performance occurs up to a threshold, where substantial break-up of the basal sheet occurs, after which the electrochemical response decreases; this is due to the destruction of the sheet integrity and lack of electrical conductive pathways. Importantly, the severity of these changes is structurally dependent on the graphene variant utilised. This work indicates that multilayer graphene has more potential as an electrochemical platform for the HER, rather than that of mono- and few-layer graphene. There is huge potential for this knowledge to be usefully exploited within the energy sector and beyond.

The origin of electron transfer at Chemical Vapour Deposition (CVD) grown monolayer graphene using a polymer-free transfer methodology is explored through the selective electrodeposition of Molybdenum (di)oxide (MoO2). The electrochemical decoration of CVD monolayer graphene with MoO2 is shown to originate from the edge plane like- sites/defects. Edge plane decoration of MoO2 nanowires upon monolayer graphene is observed via electrochemical deposition over short time periods only (ca. −0.6 V for 1 second (vs. Ag/AgCl)). At more electrochemically negative potentials (ca. −1.0 V) or longer deposition times, a large MoO2 film is created/deposited on the graphene sheet, originating and expanding from the original nucleation points at edge plane like- sites/defects/wrinkles. Nanowire fabrication along the edge plane like- sites/defects of graphene is confirmed with Cyclic Voltammetry, Scanning Electron Microscopy (SEM), Atomic Force Microscopy (AFM) and Raman Spectroscopy. Monitoring the electrochemical response towards [Ru(NH3)6]3+/2+ and comparing the heterogeneous electron transfer (HET) kinetics at CVD grown monolayer graphene prior and post nanowire fabrication reveals key understandings into the fundamental electrochemical properties of carbon materials. The HET kinetics ($${{\boldsymbol{k}}}_{{\boldsymbol{obs}}}^{{\bf{0}}}$$ k obs 0 ) at MoO2 nanowire decorated monolayer graphene sheets, when edge plane like- sites/defects have been coated/blocked with MoO2, are significantly reduced in comparison to the unmodified graphene alternative. Interestingly, MoO2 nucleation originates on the edge plane like- sites/defects of the graphene sheets, where the basal plane sites remain unaltered until the available edge plane like- sites/defects have been fully utilised; after which MoO2 deposition propagates towards and onto the basal planes, eventually covering the entire surface of the monolayer graphene surface. In such instances, there is no longer an observable electrochemical response. This work demonstrates the distinct electron transfer properties of edge and basal plane sites on CVD grown monolayer graphene, inferring favourable electrochemical reactivity at edge plane like- sites/defects and clarifying the origin of graphene electro-activity.

Correction for ‘Imaging the reactivity and width of graphene's boundary region’ by Huda S. AlSalem et al., Chem. Commun., 2020, 56, 9612–9615, DOI: 10.1039/D0CC02675A.

This paper reports the detection of the inflammatory and sepsis-related biomarker, interleukin-6 (IL-6), in human blood plasma using functionalized screen-printed electrodes (SPEs) in conjunction with a thermal detection methodology, termed heat-transfer method (HTM). SPEs are functionalized with antibodies specific for IL-6 through electrodeposition of a diazonium linking group and N'-ethylcarbodiimide hydrochloride (EDC) coupling, which was tracked through the use of cyclic voltammetry and Raman spectroscopy. The functionalized SPEs are mounted inside an additively manufactured flow cell and connected to the HTM device. We demonstrate the ability to detect IL-6 at clinically relevant concentrations in PBS buffer (pH = 7.4) with no significant interference from the similarly sized sepsis-related biomarker procalcitonin (PCT). The limit of detection (3σ) of the system is calculated to correspond to 3.4 ± 0.2 pg mL-1 with a working range spanning the physiologically relevant concentration levels in both healthy individuals and patients with sepsis, indicating the sensitivity of the sensor is suitable for the application. Further experiments helped provide a proof-of-application through the detection of IL-6 in blood plasma with no significant interference observed from PCT or the constituents of the medium. Due to the selectivity, sensitivity, straightforward operation, and low cost of production, this sensor platform has the potential for use as a traffic light sensor for the multidetection of inflammatory biomarkers for the diagnosis of sepsis and other conditions in which the rapid testing of blood biomarkers has vital clinical application.

We present the fabrication of platinum (Pt⁰) nanoparticle (ca. 3 nm average diameter) decorated vertically aligned graphene (VG) screen-printed electrodes (Pt/VG-SPE) and explore their physicochemical characteristics and electrocatalytic activity towards the hydrogen evolution reaction (HER) in acidic media (0.5 M H₂SO₄). The Pt/VG-SPEs exhibit remarkable HER activity with an overpotential (recorded at −10 mA cm−²) and Tafel value of 47 mV (vs. RHE) and 27 mV dec−¹. These values demonstrate the Pt/VG-SPEs as significantly more electrocatalytic than a bare/unmodified VG-SPE (789 mV (vs. RHE) and 97 mV dec−¹). The uniform coverage of Pt⁰ nanoparticles (ca. 3 nm) upon the VG-SPE support results in a low loading of Pt⁰ nanoparticles (ca. 4 µg cm−²), yet yields comparable HER activity to optimal Pt based catalysts reported in the literature, with the advantages of being comparatively cheap, highly reproducible and tailorable platforms for HER catalysis. In order to test any potential dissolution of Pt⁰ from the Pt/VG-SPE surface, which is a key consideration for any HER catalyst, we additively manufactured (AM) a bespoke electrochemical flow cell that allowed for the electrolyte to be collected at regular intervals and analysed via inductively coupled plasma optical emission spectroscopy (ICP-OES). The AM electrochemical cell can be rapidly tailored to a plethora of geometries making it compatible with any size/shape of electrochemical platform. This work presents a novel and highly competitive HER platform and a novel AM technique for exploring the extent of Pt⁰ nanoparticle dissolution upon the electrode surface, making it an essential study for those seeking to test the stability/catalyst discharge of their given electrochemical platforms.

The reactivity of graphene at its boundary region has been imaged using non-linear spectroscopy to address the controversy whether the terraces of graphene or its edges are more reactive. Graphene was functionalised with phenyl groups, and we subsequently scanned our vibrational sum-frequency generation setup from the functionalised graphene terraces across the edges. A greater phenyl signal is clearly observed at the edges, showing evidence of increased reactivity in the boundary region. We estimate an upper limit of 1 mm for the width of the CVD graphene boundary region.

The electrochemical response of different morphologies (microstructures) of vertically aligned graphene (VG) configurations is reported. Electrochemical properties are analysed using the outer-sphere redox probes Ru(NH3)62+/3+ (RuHex) and N,N,N′,N′-tetramethyl-p-phenylenediamine (TMPD), with performances de-convoluted via accompanying physicochemical characterisation (Raman, TEM, SEM, AFM and XPS). The VG electrodes are fabricated using an electron cyclotron resonance chemical vapour deposition (ECR-CVD) methodology, creating vertical graphene with a range of differing heights, spacing and edge plane like-sites/defects (supported upon underlying SiO2/Si). We correlate the electrochemical reactivity/response of these novel VG configurations with the level of edge plane sites (%-edge) comprising their structure and calculate corresponding heterogeneous electron transfer (HET) rates, k0. Taller VG structures with more condensed layer stacking (hence a larger global coverage of exposed edge plane sites) are shown to exhibit improved HET kinetics, supporting the claims that edge plane sites are the predominant source of electron transfer in carbon materials. A measured k0eff of ca. 4.00 × 10−3 cm s−1 (corresponding to an exposed surface coverage of active edge plane like-sites/defects (% θedge) of 1.00%) was evident for the tallest and most closely stacked VG sample, with the inverse case true, where a VG electrode possessing large inter-aligned-graphene spacing and small flake heights exhibited only 0.08% of % θedge and a k0eff value one order of magnitude slower at ca. 3.05 × 10−4 cm s−1. Control experiments are provided with conventional CVD (horizontal) grown graphene and the edge plane of highly ordered pyrolytic graphite (EPPG of HOPG), demonstrating that the novel VG electrodes exhibit ca. 3× faster k0 than horizontal CVD graphene. EPPG exhibited the fastest HET kinetics, exhibiting ca. 2× larger k0 than the best VG. These results are of significance to those working in the field of 2D-carbon electrochemistry and materials scientists, providing evidence that the macroscale electrochemical response of carbon-based electrodes is dependent on the edge plane content and showing that a range of structural configurations can be employed for tailored properties and applications. D. A. C. Brownson acknowledges funding from the Ramsay Memorial Fellowships Trust. Funding from the Engineering and Physical Science Research Council (Reference: EP/N001877/1), a British Council Institutional Grant Link (No. 172726574) and Innovate UK (KTP Reference: 11606) is acknowledged.

Additively manufactured (AM) supercapacitor platforms are fabricated from bespoke filaments, which are comprised of electro-conductive graphene (20 wt%) incorporated polylactic acid (80 wt%), via fused deposition modeling and denoted as G/AMEs. The G/AMEs are shown to be capable of acting as a template for the electrodeposition of metals/metal oxides, in particular MoO2 nanowires (MoO2-G/AMEs), which are subsequently explored as a capacitor within 1 m H2SO4, 1-butyl-3-methylimidazolium hexafluorophosphate, and 1-butyl-3-methylimidazolium tetrafluoroborate. Optimization of the MoO2-G/AMEs demonstrates capacitance up to 1212 F g–1 when used in a symmetric arrangement. The material science described herein represents a significant enhancement in unlocking AMs potential as a valid manufacturing route for device level capacitance architectures.

This short article overviews the use of screen-printed electrodes (SPEs) in the field of electroanalysis and compares their application against traditional laboratory based analytical techniques. Electroanalysis coupled with SPEs can offer low-cost, precise, sensitive, rapid, quantitative information and laboratory equivalent results. The combined use of SPEs and electroanalysis reduces the need of sample transportation and preparation to a centralised laboratory allowing experimentalists to perform the measurements where they are needed the most. We first introduce the basic concepts and principles of analytical techniques to the reader, with particular attention to electroanalysis, and then discuss the application of SPEs to common analytical targets such as food, environmental, forensics, cancer biomarkers and pathogenic monitoring and sensing.

© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim Mono-, few- and multi- layer graphene is explored towards the electrochemical Oxygen Evolution Reaction (OER). Raman mapping characterisation is performed, revealing that the structure of basal plane graphene is damaged due to the electrochemical perturbation of the OER. Electrochemical perturbation, in the form of electrochemical potential scanning (linear sweep voltammetry), and a thorough comparison of the OER at different scan rates and chronoamperometry tests at different voltages, create active edge plane sites/defects upon the basal plane graphene surface in the case of the mono- and few- layer graphene electrodes. The electrochemical performance gradually decreases with consecutive OER scans upon a given graphene electrode, with the process damaging the basal plane graphene sheet, after which there is a loss in the electrochemical signal due to a loss in electrically conductive pathways. Importantly, the severity of these changes is dependent on the potential and chosen scan rate that is applied to the graphene electrode. In contrast, however, multilayer graphene's initial performance towards the OER process improves after the first few scans, which is likely due to an increase in the coverage of edge plane sites/defects and its underlying layers maintaining electrical contact. This work indicates the importance of the scan rate and potential limits applied to graphene electrodes in addition to the relationship between the number of layers and structural integrity. This new knowledge is of fundamental importance to be advantageously applied within the energy sector and beyond.

Monolayer hexagonal-boron nitride films (2D-hBN) are typically reported within the literature to be electrochemically inactive due to their considerable band gap (

Herein, we report the fabrication and application of Li‐ion anodes for utilisation within Li‐ion batteries, which are fabricated via additive manufacturing/3D printing (fused deposition modelling) using a bespoke graphene/polylactic acid (PLA) filament, where the graphene content can be readily tailored and controlled over the range 1–40 wt. %. We demonstrate that a graphene content of 20 wt. % exhibits sufficient conductivity and critically, effective 3D printability for the rapid manufacturing of 3D printed freestanding anodes (3DAs); simplifying the components of the Li‐ion battery negating the need for a copper current collector. The 3DAs are physicochemically and electrochemically characterised and possess sufficient conductivity for electrochemical studies. Critically, it is found that if the 3DAs are used in Li‐ion batteries the specific capacity is very poor but can be significantly improved through the use of a chemical pre‐treatment. Such treatment induces an increased porosity, which results in a 200‐fold increase (after anode stabilisation) of the specific capacity (ca. 500 mAh g−1 at a current density of 40 mA g−1). This work significantly enhances the field of additive manufacturing/3D printed graphene based energy storage devices demonstrating that useful 3D printable batteries can be realised.

The constant and persistent synthesis and abuse of new psychoactive substances have sparked the requirement for rapid, on-site, sensitive analytical protocols for their sensing and quantification. Mephedrone (4-MMC) is currently one of the most popular legal highs among recreational drug abusers and imposes a serious public health problem. In this paper, the electrochemical sensing of two metabolites of 4-MMC, namely, nor-mephedrone (4-methylcathinone, 4-MC) and dihydromephedrone (4-methylephedrine, 4-MMC-R), utilizing screen-printed graphite electrodes is performed. The accessible linear ranges by cyclic voltammetry were found to correspond to 40–300 μg mL–1 for 4-MC in both phosphate buffer solution (PBS, pH 7.0) and spiked diluted human urine, whereas in the case of 4-MMC-R, the linearity ranges are 15–300 μg mL–1 (PBS, pH 3.0) and 25–300 μg mL–1 (spiked diluted human urine). To maximize the assay sensitivity, differential pulse voltammetry (DPV) was performed toward the sensing of 4-MC, which exhibited a linear response over the range 10–250 and 10–300 μg mL–1 in PBS pH 7.0 and spiked diluted human urine, respectively. However, 4-MMC-R demonstrated slightly higher sensitivity over the range 5–300 μg mL–1 in both PBS pH 3.0 and spiked diluted human urine. Using DPV, the limits of detection (3σ) were calculated and found to correspond to ca. 3.97 and 3.64 μg mL–1 for 4-MC and 4-MMC-R (PBS, pH 7.0 and 3.0), respectively, and ca. 6.34 and 3.87 μg mL–1 for 4-MC and 4-MMC-R (spiked diluted human urine), respectively. The potential interference of adulterants’ metabolites commonly found in NPS street samples was also explored (at both pH 7.0 and 3.0). The electrochemical approach reported herein provides a novel laboratory tool for the identification and quantification of synthetic cathinone metabolites and has potential for the basis of a portable analytical sensor for their fast, cheap, reliable, and accessible determination in the field.

Currently there is a global interest in the application of 2D materials such as graphene, graphene oxide (GO), reduced graphene oxide (rGO), 2D hexagonal boron nitride (2D-hBN), MoSe2, MoS2, WSe2, antimonene and phosphorene within electrochemical applications. Some of those applications range from their use as sensors and energy storage/generation devices, including its use as an electrochemical supercapacitor, lithium/sodium ion batteries and as anodes and cathodes within fuel cells, to name just a few. This global interest is due to the unique beneficial properties of the 2D materials over traditional electrochemical materials. As a result, there is a need to fundamentally understand how these 2D materials behave as electrodes at the single layer scale within electrochemical systems, and develop enhanced 2D materials into useful 3D structures, e.g. as 3D printed structures/electrodes. The discovery and/or confirmation of the fundamental electrochemical properties of these 2D materials could enable its application in several areas, such as additive manufacturing, electronics, and energy storage/generation for electrochemical sensor platforms. There is a huge potential for this knowledge to be usefully exploited within sensing and energy sectors and beyond. This thesis reports the electrochemistry of graphene and other 2D nanomaterials from a fundamental point of view with thorough physicochemical characterisation and resultant electrochemical applicability of using 2D materials as electrodes. Chapter 1 gives an overview of the fundamental concepts of electrochemistry and 2D materials related to this thesis. Chapter 2 details relevant experimental information used in this thesis. 8 Chapter 3 compares methods to determine the electroactive area of CVD grown graphene, which is important and novel contribution to those experimentalist using this and other electrode materials in order to benchmark their electrode platform. Chapter 4 demonstrates the origin of electron transfer properties of edge and basal plane sites on true graphene (polymer-free transferred and single layer). Chapters 5 and 6 study, for the first time, the applicability and structural integrity of CVD graphene sheets towards the water splitting reactions depending on the number of layers, scan rate and voltage applied towards energy applications, indicating that mono- and few-layer CVD graphene are not suitable electrode materials towards the HER and the OER. Such work is of fundamental importance when graphene surfaces are use either “as is” or as the basis of catalyst as used in the HER/OER (Chapter 5 and 6 respectively). Chapter 7 explores the introduction of physical linear defects (PLDs) on the surface of monolayer hexagonal-boron nitride films (2D-hBN), in order change from an insulator to a semiconductor material, tailoring its electrochemical properties. Physicochemical, computational and electrochemical characterisation techniques are applied to identify/explain the change in the electrochemical response from the change in surface morphology. 2D-hBN typically is considered an electrochemical insulator, however this thesis reports that through implementation of physical defects (simple surface modifications) the bandgap changes from ca. 6.11 eV to ca. 2.36 eV, giving rise to electrochemically useful signatures towards RuHex, Fe+2/+3 and the HER.. Chapter 8 explores the use of different lateral flake sizes of graphitic powders in paste electrodes, applying the knowledge from Chapter 4, to obtain enhanced sensor devices by using smaller lateral flake sizes graphitic materials. 9 Lastly, chapter 9 explores the additive manufacturing of Graphene/PLA composites, namely thin films, 3D printable filaments and 3D printed electrodes, demonstrating that useful low cost 3D printable electrode can be manufactured and applied towards electroanalytical applications.

An electrochemical method for the determination of Taxifolin (Tx) in peanut oil samples using screen-printed electrodes (SPEs) is reported for the first time. The different electroanalytical parameters such as scan rate, supporting electrolyte, pH and accumulation step were optimized. Interference studies were also explored for the determination of Tx in presence of daidzein, quercetin, trans-resveratrol and caffeic acid. The method developed for the Tx determination exhibits a linear response in the concentration range from 0.05 to 1 μM and a limit of detection of 0.021 μM. The electrochemical detection method proposed provides a novel, quick, low-cost, reliable and portable method for the in-situ quality control for monitoring the protected designation of origin of the “Córdoba, Argentina, Peanuts”. Fil: Pierini, Gastón Dario. Universidad Nacional de Río Cuarto. Instituto para el Desarrollo Agroindustrial y de la Salud. - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto para el Desarrollo Agroindustrial y de la Salud; Argentina. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Departamento de Química; Argentina Fil: Maccio, Sabrina Antonella. Universidad Nacional de Río Cuarto. Instituto para el Desarrollo Agroindustrial y de la Salud. - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto para el Desarrollo Agroindustrial y de la Salud; Argentina. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Departamento de Química; Argentina Fil: Robledo, Sebastian Noel. Universidad Nacional de Río Cuarto. Instituto para el Desarrollo Agroindustrial y de la Salud. - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto para el Desarrollo Agroindustrial y de la Salud; Argentina. Universidad Nacional de Río Cuarto. Facultad de Ingeniería. Departamento de Tecnología Química; Argentina Fil: García Miranda Ferrari, Alejandro. Manchester Metropolitan University; Reino Unido Fil: Banks, Craig E.. Manchester Metropolitan University; Reino Unido Fil: Fernandez, Hector. Universidad Nacional de Río Cuarto. Instituto para el Desarrollo Agroindustrial y de la Salud. - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto para el Desarrollo Agroindustrial y de la Salud; Argentina. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Departamento de Química; Argentina Fil: Zon, María Alicia. Universidad Nacional de Río Cuarto. Instituto para el Desarrollo Agroindustrial y de la Salud. - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto para el Desarrollo Agroindustrial y de la Salud; Argentina. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Departamento de Química; Argentina

Screen-printed electrochemical sensing platforms, due to their scales of economy and high reproducibility, can provide a useful approach to translate laboratory-based electrochemistry into the field. An important factor when utilising screen-printed electrodes (SPEs) is the determination of their real electrochemical surface area, which allows for the benchmarking of these SPEs and is an important parameter in quality control. In this paper, we consider the use of cyclic voltammetry and chronocoulometry to allow for the determination of the real electrochemical area of screen-printed electrochemical sensing platforms, highlighting to experimentalists the various parameters that need to be diligently considered and controlled in order to obtain useful measurements of the real electroactive area.

In this work, mass-fabricated stainless-steel pins are used as low-cost electrodes in a batch injection analysis (BIA) system with electrochemical detection (BIA-ED). The system consists of a polypropylene container including a potentiostatic three-electrode configuration cell designed using a pin coated with carbon ink as working electrode and two bare pins as counter and reference electrodes. These pins are directly punched into the bottom of the container and connected to the potentiostat using a commercial female connection. The system shows good precision for measurements performed employing the same or different electrochemical cells (RSD 7.2 and 8.9% respectively). The platform is applied to the determination of epinephrine in a pharmaceutical real sample showing accurate results. As a proof-of-concept, the feasibility of constructing a multiplexed BIA-ED system based on pins is evaluated by incorporating eight pin-based working electrodes in the container. The electroanalytical platform is completed with one reference and one auxiliary pin electrodes that are shared for all the eight working electrodes. It demonstrates the versatility that pins can provide to the construction of different electroanalytical systems. Moreover, the system is designed in such a way that an eight-channel micropipette can be employed for injections, making the system simpler and faster., This work has been supported by the CTQ2014-58826-R project from the Spanish Ministry of Economy and Competitiveness (MINECO).