Quantitative Measurement Technique for Anodic Corrosion of BDD Advanced Oxidation Electrodes.

Electrochemical advanced oxidation (EAO) systems are of significant interest due to their ability to treat a wide range of organic contaminants in water. Boron doped diamond (BDD) electrodes have found considerable use in EAO. Despite their popularity, no laboratory scale method exists to quantify anodic corrosion of BDD electrodes under EAO conditions; all are qualitative using techniques such as scanning electron microscopy, electrochemistry, and spectroscopy.

A Current Averaging Strategy for Maximizing Analyte and Minimizing Redox Interference Signals with Square Wave Voltammetry.

Square wave voltammetry (SWV) is commonly used in electroanalytical applications to enhance analyte faradaic signals and minimize nonfaradaic processes. However, little attention is given as to how best use SWV to minimize faradaic interference signals that arise from redox species present in solution that have redox potentials that convolute with that of the analyte. In conventional SWV, a series of current-time (-) transients are collected, and is averaged over a specified window of each transient (potentiostat dependent).

Simulation of the cyclic voltammetric response of an outer-sphere redox species with inclusion of electrical double layer structure and ohmic potential drop.

A finite-element model has been developed to simulate the cyclic voltammetric (CV) response of a planar electrode for a 1e outer-sphere redox process, which fully accounts for cell electrostatics, including ohmic potential drop, ion migration, and the structure of the potential-dependent electric double layer. Both reversible and quasi-reversible redox reactions are treated. The simulations compute the time-dependent electric potential and ion distributions across the entire cell during a voltammetric scan.

Electron Paramagnetic Resonance for the Detection of Electrochemically Generated Hydroxyl Radicals: Issues Associated with Electrochemical Oxidation of the Spin Trap.

For the detection of electrochemically produced hydroxyl radicals (HO) from the oxidation of water on a boron-doped diamond (BDD) electrode, electron paramagnetic resonance spectroscopy (EPR) in combination with spin trap labels is a popular technique. Here, we show that quantification of the concentration of HO from water oxidation via spin trap electrochemical (EC)-EPR is problematic. This is primarily due to the spin trap oxidizing at potentials less positive than water, resulting in the same spin trap-OH adduct as formed from the solution reaction of OH with the spin trap.

Electron Beam Transparent Boron Doped Diamond Electrodes for Combined Electrochemistry-Transmission Electron Microscopy.

The majority of carbon based transmission electron microscopy (TEM) platforms (grids) have a significant sp carbon component. Here, we report a top down fabrication technique for producing freestanding, robust, electron beam transparent and conductive sp carbon substrates from boron doped diamond (BDD) using an ion milling/polishing process. X-ray photoelectron spectroscopy and electrochemical measurements reveal the sp carbon character and advantageous electrochemical properties of a BDD electrode are retained during the milling process.

Finite Element Modeling of the Combined Faradaic and Electrostatic Contributions to the Voltammetric Response of Monolayer Redox Films.

The voltammetric response of electrodes coated with a redox-active monolayer is computed by finite element simulations based on a generalized model that couples the Butler-Volmer, Nernst-Planck, and Poisson equations. This model represents the most complete treatment of the voltammetric response of a redox film to date and is made accessible to the experimentalist via the use of finite element modeling and a COMSOL-generated report. The model yields a full description of the electric potential and charge distributions across the monolayer and bulk solution, including the potential distribution associated with ohmic resistance.

Versatile DIY Route for Incorporation of a Wide Range of Electrode Materials into Rotating Ring Disk Electrodes.

Rotating ring disk electrodes (RRDEs) are a powerful and versatile tool for mechanistically investigating electrochemical reactions at electrode surfaces, particularly in the area of electroanalysis and catalysis. Despite their importance, only limited electrode materials (typically glassy carbon, platinum, and gold) and combinations thereof are available commercially. In this work, we present a method employing three-dimensional (3D) printing in conjunction with machined brass components to produce housing, which can accommodate any electrode material in, .

Ultrafast transient absorption spectroelectrochemistry: femtosecond to nanosecond excited-state relaxation dynamics of the individual components of an anthraquinone redox couple.

Many photoactivated processes involve a change in oxidation state during the reaction pathway and formation of highly reactive photoactivated species. Isolating these reactive species and studying their early-stage femtosecond to nanosecond (fs-ns) photodynamics can be challenging. Here we introduce a combined ultrafast transient absorption-spectroelectrochemistry (TA-SEC) approach using freestanding boron doped diamond (BDD) mesh electrodes, which also extends the time domain of conventional spectrochemical measurements.

Miniaturized probe on polymer SU-8 with array of individually addressable microelectrodes for electrochemical analysis in neural and other biological tissues.

An SU-8 probe with an array of nine, individually addressable gold microband electrodes (100 μm long, 4 μm wide, separated by 4-μm gaps) was photolithographically fabricated and characterized for detection of low concentrations of chemicals in confined spaces and in vivo studies of biological tissues. The probe's shank (6 mm long, 100 μm wide, 100 μm thick) is flexible, but exhibits sufficient sharpness and rigidity to be inserted into soft tissue. Laser micromachining was used to define probe geometry by spatially revealing the underlying sacrificial aluminum layer, which was then etched to free the probes from a silicon wafer.

Lifting the lid on the potentiostat: a beginner's guide to understanding electrochemical circuitry and practical operation.

Students who undertake practical electrochemistry experiments for the first time will come face to face with the potentiostat. To many this is simply a box containing electronics which enables a potential to be applied between a working and reference electrode, and a current to flow between the working and counter electrode, both of which are outputted to the experimentalist. Given the broad generality of electrochemistry across many disciplines it is these days very common for students entering the field to have a minimal background in electronics.

Combined Voltammetric Measurement of pH and Free Chlorine Speciation Using a Micro-Spot sp Bonded Carbon-Boron Doped Diamond Electrode.

This work demonstrates the use of an sp-bonded carbon microspot boron doped diamond (BDD) electrode for voltammetric measurement of both pH and analyte concentration in a pH-dependent speciation process. In particular, the electrode was employed for the voltammetric detection of pH and hypochlorite (OCl) in unbuffered, aerated solutions over the pH range 4-10. Knowledge of both pH and [OCl] is essential for determination of free chlorine concentration.

Controlling palladium morphology in electrodeposition from nanoparticles to dendrites the use of mixed solvents.

By changing the mole fraction of water (χwater) in the solvent acetonitrile (MeCN), we report a simple procedure to control nanostructure morphology during electrodeposition. We focus on the electrodeposition of palladium (Pd) on electron beam transparent boron-doped diamond (BDD) electrodes. Three solutions are employed, MeCN rich (90% v/v MeCN, χwater = 0.

Electrochemical pH Mapping of the Gastrointestinal Tract in the Absence and Presence of Pharmacological Agents.

pH profiling of the upper gastrointestinal (GI) tract (of a mouse), using an electrochemical pH probe, in both the absence and presence of pharmacological agents aimed at altering acid/bicarbonate production, is reported. Three pH electrodes were first assessed for suitability using a GI tract biological mimic buffer solution containing 0.5% mucin.

Investigation of sp-Carbon Pattern Geometry in Boron-Doped Diamond Electrodes for the Electrochemical Quantification of Hypochlorite at High Concentrations.

An electrochemical sensor that contains patterned regions of sp-carbon in a boron-doped diamond (BDD) matrix is presented for the quantitative detection of hypochlorite (OCl) at high concentrations in the alkaline, chemically oxidizing environment associated with bleach. As BDD itself is unresponsive to OCl reduction within the solvent window, by using a laser micromachining process, it is possible to write robust electrochemically active regions of sp-carbon into the electrochemically inert sp-BDD electrode. In this work, four different laser patterned BDD electrodes are examined, and their response compared across a range of OCl concentrations (0.

Addressing the practicalities of anodic stripping voltammetry for heavy metal detection: a tutorial review.

Anodic Stripping Voltammetry (ASV) has the capability to detect heavy metals at sub ppb-level with portable and cheap instrumentation making it ideal for in the field (at the source) analysis, however, commercial activity is surprisingly limited. The more commonly used liquid mercury electrodes are now obsolete due to toxicity concerns, and replacements are all based around solid electrodes, which come with their own challenges. This tutorial review aims to discuss the experimental practicalities of ASV, providing a clear overview of the issues for consideration, which can serve as a guide for anyone wanting to undertake analytical ASV.

Boron Doped Diamond as a Low Biofouling Material in Aquatic Environments: Assessment of Biofilm Formation.

Boron doped diamond (BDD), given the robustness of the material, is becoming an electrode of choice for applications which require long-term electrochemical monitoring of analytes in aqueous environments. However, despite the extensive work in this area, there are no studies which directly assess the biofilm formation (biofouling) capabilities of the material, which is an essential consideration because biofouling often causes deterioration in the sensor performance. is one of the most prevalent bacterial pathogens linked to water-related diseases, with a strong capacity for forming biofilms on surfaces that are exposed to aquatic environments.

Enhancing Square Wave Voltammetry Measurements via Electrochemical Analysis of the Non-Faradaic Potential Window.

Square wave voltammetry (SWV) is most commonly used to enhance electroanalytical current signals of a redox analyte of interest. The SWV is typically recorded in a potential region where both non-faradaic and faradaic currents are collected; however, only data in the faradaic region are analyzed. In this article, we show how by collecting the full current-time ( i- t) data, arising from the SWV potential pulse sequence, and analyzing in the region of the potential scan where non-faradaic currents arise, further analytical information can be collected, over short time periods (typically seconds).

An sp Patterned Boron Doped Diamond Electrode for the Simultaneous Detection of Dissolved Oxygen and pH.

A hybrid sp-sp electrochemical sensor comprising patterned regions of nondiamond-carbon (sp) in a boron doped diamond (sp) matrix is described for the simultaneous voltammetric detection of dissolved oxygen (DO) and pH in buffered aqueous solutions. Using a laser micropatterning process it is possible to write mechanically robust regions of sp carbon into a BDD electrode. These regions both promote the electrocatalytic reduction of oxygen and facilitate the proton coupled electron transfer of quinone groups, integrated into the surface of the sp carbon.

Deconvoluting Surface-Bound Quinone Proton Coupled Electron Transfer in Unbuffered Solutions: Toward a Universal Voltammetric pH Electrode.

While quinone proton coupled electron transfer (PCET) under buffered conditions is well understood, the situation is more complicated in unbuffered aqueous solutions. With a view to producing a quinone-based voltammetric pH electrode that can function universally in both buffered and unbuffered solutions by following a two-electron (2e)/two-proton (2H) Nernstian pathway over a wide pH range, the voltammetric response of strongly electronically coupled surface-bound quinones, directly integrated into a boron-doped diamond (BDD) electrode, is investigated. A laser ablation process enables integration of quinones into the BDD electrode surface with a high p K (first protonation state) and with controllable, very low surface coverages (as low as 2 orders of magnitude below monolayer coverage).

Conductive diamond: synthesis, properties, and electrochemical applications.

Conductive diamond possesses unique features as compared to other solid electrodes, such as a wide electrochemical potential window, a low and stable background current, relatively rapid rates of electron-transfer for soluble redox systems without conventional pretreatment, long-term responses, stability, biocompatibility, and a rich surface chemistry. Conductive diamond microcrystalline and nanocrystalline films, structures and particles have been prepared using a variety of approaches. Given these highly desirable attributes, conductive diamond has found extensive use as an enabling electrode across a variety of fields encompassing chemical and biochemical sensing, environmental degradation, electrosynthesis, electrocatalysis, and energy storage and conversion.

Tracking Metal Electrodeposition Dynamics from Nucleation and Growth of a Single Atom to a Crystalline Nanoparticle.

In electrodeposition the key challenge is to obtain better control over nanostructure morphology. Currently, a lack of understanding exists concerning the initial stages of nucleation and growth, which ultimately impact the physicochemical properties of the resulting entities. Using identical location scanning transmission electron microscopy (STEM), with boron-doped diamond (BDD) serving as both an electron-transparent TEM substrate and electrode, we follow this process, from the formation of an individual metal atom through to a crystalline metal nanoparticle, under potential pulsed conditions.

Boron Doped Diamond: A Designer Electrode Material for the Twenty-First Century.

Boron doped diamond (BDD) is continuing to find numerous electrochemical applications across a diverse range of fields due to its unique properties, such as having a wide solvent window, low capacitance, and reduced resistance to fouling and mechanical robustness. In this review, we showcase the latest developments in the BDD electrochemical field. These are driven by a greater understanding of the relationship between material (surface) properties, required electrochemical performance, and improvements in synthetic growth/fabrication procedures, including material postprocessing.

Comparison of fast electron transfer kinetics at platinum, gold, glassy carbon and diamond electrodes using Fourier-transformed AC voltammetry and scanning electrochemical microscopy.

Heterogeneous electron transfer (ET) processes at electrode/electrolyte interfaces are of fundamental and applied importance and are extensively studied by a range of electrochemical techniques, all of which have various attributes but also limitations. The present study focuses on the one-electron oxidation of tetrathiafulvalene (TTF) and reduction of tetracyanoquinodimethane (TCNQ) in acetonitrile solution by two powerful electrochemical techniques: Fourier-transformed large amplitude alternating current voltammetry (FTACV); and scanning electrochemical microscopy (SECM), both of which are supported by detailed theoretical models. At conventional Pt, Au and glassy carbon (GC) electrode materials, the apparent (overall) charge transfer kinetic values determined by FTACV give standard ET rate constants, k, that are fast and close to the reversible limit.

Probing Electrode Heterogeneity Using Fourier-Transformed Alternating Current Voltammetry: Application to a Dual-Electrode Configuration.

Quantitative studies of electron transfer processes at electrode/electrolyte interfaces, originally developed for homogeneous liquid mercury or metallic electrodes, are difficult to adapt to the spatially heterogeneous nanostructured electrode materials that are now commonly used in modern electrochemistry. In this study, the impact of surface heterogeneity on Fourier-transformed alternating current voltammetry (FTACV) has been investigated theoretically under the simplest possible conditions where no overlap of diffusion layers occurs and where numerical simulations based on a 1D diffusion model are sufficient to describe the mass transport problem. Experimental data that meet these requirements can be obtained with the aqueous [Ru(NH)] redox process at a dual-electrode system comprised of electrically coupled but well-separated glassy carbon (GC) and boron-doped diamond (BDD) electrodes.