Unusual Electrochemical Properties of Low-Doped Boron-Doped Diamond Electrodes Containing sp2 Carbon

Generation of Rare Sugars by Electrochemical Oxidation of d-Glucose Using Boron-Doped Diamond Electrode

The electrochemical oxidation of biomass for the production of value-added chemicals represents a promising approach in the field of sustainable chemistry. In this study, we investigated the electrochemical conversion of d-glucose, a biomass-derived compound, using boron-doped diamond (BDD) electrodes under constant applied current (10 mA) or potentials (1.5-3.0 V vs Ag/AgCl). The reaction products were analyzed using high-performance liquid chromatography (HPLC) and liquid chromatography/mass spectrometry (LC/MS) measurements, employing both p-aminobenzoic acid ethyl ester (ABEE) and l-tryptophan amide labeling methods to enable characterization. The results demonstrated that the BDD electrodes achieved 95.9% d-glucose degradation and successfully generated various rare sugars, including d-arabinose (0.126 mmol/L), d-erythrose (0.0544 mmol/L), d-glyceraldehyde, and l-glyceraldehyde (combined 0.148 mmol/L). Under identical conditions, Pt electrodes as a control showed only 10.2% d-glucose degradation with significantly lower rare sugar yields. The applied potential significantly influenced the product distribution, with optimal rare sugar production observed at 2.5 V vs Ag/AgCl, reflecting a balance between glucose oxidation and product degradation. Mechanistic studies suggest that the formation of rare sugars involves a series of oxidation and decarboxylation reactions, facilitated by electrochemically generated active species. The superior performance of the BDD electrodes is attributed to their wide potential window, efficient generation of oxidizing species, and unique surface characteristics. This research provides new insights into the electrochemical transformation of biomass-derived compounds and demonstrates the potential for sustainable production of high-value rare sugars, opening avenues for applications in food science, pharmaceuticals, and green chemistry.

One-Step Solvothermal Synthesis of Carbon Dots for Rapid and Accurate Determination of Hemin Content

The development of sensitive and specific methods for the high-quality analysis of hemin-related drugs is significant in the pharmaceutical field. In this work, a simple and rapid method based on the fluorescent properties of carbon dots (CDs) was established for the determination of hemin in drugs. By taking melamine and ethylenediamine as the reaction materials, the fluorescent CDs were synthesized by a one-step solvothermal method, which can be used for the determination of hemin in drugs by the fluorescent inner filter effect. The as-prepared fluorescent CDs with rich functional groups on the surface displayed good water solubility, strong salt resistance, robust pH stability, and photobleaching resistance. Most importantly, the fluorescent excitation wavelength of fluorescent CDs was very close to the absorption wavelength of hemin, providing the evidence for the fluorescent inner filter effect. When the hemin concentration was in the range of 0.01-1 μM, there was a good linear relationship between the hemin content with the fluorescence intensity of CDs. The linear regression equation was (1 - F/F0) = 0.0897c + 0.0124, with a correlation coefficient (R2) of 0.9982 and a detection limit of 9 nM. This assay was successfully used to determine the content of hemin in the tablet, which displayed 97.9-105.5% of the labelled amount, with a relative standard deviation of less than 3%. The developed fluorescence method for the detection of hemin content displays the advantages of accurate, rapid, and high sensitivity, which could prove to be a useful tool for the determination of hemin supplement tablets.

Interlayer Affected Diamond Electrochemistry

Diamond electrochemistry is primarily influenced by quantities of sp3-carbon, surface terminations, and crystalline structure. In this work, a new dimension is introduced by investigating the effect of using substrate-interlayers for diamond growth. Boron and nitrogen co-doped nanocrystalline diamond (BNDD) films are grown on Si substrate without and with Ti and Ta as interlayers, named BNDD/Si, BNDD/Ti/Si, and BNDD/Ta/Ti/Si, respectively. After detailed characterization using microscopies, spectroscopies, electrochemical techniques, and density functional theory simulations, the relationship of composition, interfacial structure, charge transport, and electrochemical properties of the interface between diamond and metal is investigated. The BNDD/Ta/Ti/Si electrodes exhibit faster electron transfer processes than the other two diamond electrodes. The interlayer thus determines the intrinsic activity and reaction kinetics. The reduction in their barrier widths can be attributed to the formation of TaC, which facilitates carrier tunneling, and simultaneously increases the concentration of electrically active defects. As a case study, the BNDD/Ta/Ti/Si electrode is further employed to assemble a redox-electrolyte-based supercapacitor device with enhanced performance. In summary, the study not only sheds light on the intricate relationship between interlayer composition, charge transfer, and electrochemical performance but also demonstrates the potential of tailored interlayer design to unlock new capabilities in diamond-based electrochemical devices.

High-Temperature Optoelectronic Transport Behavior of n-TiO2 Nanoball-Stick/p-Lightly Boron-Doped Diamond Heterojunction

The n-TiO2 nanoballs-sticks (TiO2 NBSs) were successfully deposited on p-lightly boron-doped diamond (LBDD) substrates by the hydrothermal method. The temperature-dependent optoelectronic properties and carrier transport behavior of the n-TiO2 NBS/p-LBDD heterojunction were investigated. The photoluminescence (PL) of the heterojunction detected four distinct emission peaks at 402 nm, 410 nm, 429 nm, and 456 nm that have the potential to be applied in white-green light-emitting devices. The results of the I-V characteristic of the heterojunction exhibited excellent rectification characteristics and good thermal stability at all temperatures (RT-200 °C). The forward bias current increases gradually with the increase in external temperature. The temperature of 150 °C is ideal for the heterojunction to exhibit the best electrical performance with minimum turn-on voltage (0.4 V), the highest forward bias current (0.295 A ± 0.103 mA), and the largest rectification ratio (16.39 ± 0.005). It is transformed into a backward diode at 200 °C, which is attributed to a large number of carriers tunneling from the valence band (VB) of TiO2 to the conduction band (CB) of LBDD, forming an obvious reverse rectification effect. The carrier tunneling mechanism at different temperatures and voltages is analyzed in detail based on the schematic energy band structure and semiconductor theoretical model.

A Free-Standing Boron-Doped Diamond Grid Electrode for Fundamental Spectroelectrochemistry

Spectroelectrochemistry (SEC) is a powerful technique that enables a variety of redox properties to be studied, including formal potential (Eo), thermodynamic values (ΔG, ΔH, ΔS), diffusion coefficient (D), electron transfer stoichiometry (n), and others. SEC requires an electrode which light can pass through while maintaining sufficient electrical conductivity. This has been traditionally composed of metal or metal oxide films atop transparent substrates like glass, quartz, or metallic mesh. Robust electrode materials like boron-doped diamond (BDD) could help expand the environments in which SEC can be performed, but most designs are limited to thin films (∼100-200 nm) on transparent substrates less resilient than free-standing BDD. This work presents a free-standing BDD grid electrode (G-BDD) for fundamental SEC measurements, using the well-characterized Fe(CN)63-/4- redox couple as proof-of-concept. With a combination of cyclic voltammetry (CV), thin-layer SEC, and chronoabsorptometry, several of the redox properties mentioned above were calculated and compared. For Eo', n, and D, similar results were obtained when comparing the CV [Eo' = +0.279 (±0.002) V vs Ag/AgCl; n = 0.97; D = 4.1 × 10-6 cm2·s-1] and SEC [Eo' = +0.278 (±0.001) V vs Ag/AgCl; n = 0.91; D = 5.2 × 10-6 cm2·s-1] techniques. Both values align with what has been previously reported. To calculate D from the SEC data, modification of the classical equation used in chronoabsorptometry was required to accommodate the G-BDD electrode geometry. Overall, this work expands on the applicability of SEC techniques and BDD as a versatile electrode material.

Low-interference and sensitive electrochemical detection of glucose and lactate using boron-doped diamond electrode and electron mediator menadione

To minimize background interference in electrochemical enzymatic biosensors employing electron mediators, it is essential for the electrochemical oxidation of electroactive interfering species (ISs), such as ascorbic acid (AA), to proceed slowly, and for the redox reactions between electron mediators and ISs to occur at a low rate. In this study, we introduce a novel combination of a working electrode and an electron mediator that effectively mitigates interference effects. Compared to commonly used electrodes such as Au, glassy carbon, and indium tin oxide (ITO), boron-doped diamond (BDD) electrodes demonstrate significantly lower anodic current (i.e., lower background levels) in the presence of AA. Additionally, menadione (MD) exhibits notably slower reactivity with AA compared to other electron mediators such as Ru(NH3)63+, 4-amino-1-naphthol, and 1,4-naphthoquinone, primarily due to the lower formal potential of MD compared to AA. This synergistic combination of BDD electrode and MD is effectively applied in three biosensors: (i) glucose detection using electrochemical-enzymatic (EN) redox cycling, (ii) glucose detection using electrochemical-enzymatic-enzymatic (ENN) redox cycling, and (iii) lactate detection using ENN redox cycling. Our developed approach significantly outperforms the combination of ITO electrode and MD in minimizing IS interference. Glucose in artificial serum can be detected with detection limits of ~ 20 μM and ~ 3 μM in EN and ENN redox cycling, respectively. Furthermore, lactate in human serum can be detected with a detection limit of ~ 30 μM. This study demonstrates sensitive glucose and lactate detection with minimal interference, eliminating the need for (bio)chemical agents to remove interfering species.

Photoelectrocatalytic degradation of high-density polyethylene microplastics on TiO2-modified boron-doped diamond photoanode

Microplastic (MP) accumulation in the environment is accelerating rapidly, which has led to their effects on both the ecosystem and human life garnering much attention. This study is the first to examine the degradation of high-density polyethylene (HDPE) MPs via photoelectrocatalysis (PEC) using a TiO2-modified boron-doped diamond (BDD/TiO2) photoanode. This study was divided into three stages: (i) preparation of the photoanode through electrophoretic deposition of synthetic TiO2 nanoparticles on a BDD electrode; (ii) characterization of the modified photoanode using electrochemical, structural, and optical techniques; and (iii) degradation of HDPE MPs by electrochemical oxidation and photoelectrocatalysis on bare and modified BDD electrodes under dark and UV light conditions. The results indicate that the PEC technique degraded 89.91 ± 0.08% of HDPE MPs in a 10-h reaction and was more efficient at a lower current density (6.89 mA cm-1) with the BDD/TiO2 photoanode compared to electrochemical oxidation on bare BDD.

Electrochemical decarboxylation of acetic acid on boron-doped diamond and platinum-functionalised electrodes for pyrolysis-oil treatment

Electrochemical decarboxylation of acetic acid on boron-doped-diamond (BDD) electrodes was studied as a possible means to decrease the acidity of pyrolysis oil. It is shown that decarboxylation occurs without the competitive oxygen evolution reaction (OER) on BDD electrodes to form methanol and methyl acetate by consecutive reaction of hydroxyl radicals with acetic acid. The performance is little affected by the applied current density (and associated potential), concentration, and the pH of the solution. At current densities above 50 mA cm-2, faradaic efficiencies (FEs) of 90% towards the decarboxylation products are obtained, confirmed by in situ electrochemical mass spectrometry (ECMS) investigation showing only small amounts of oxygen formed by water oxidation. Using platinum-modified BDD electrodes, it is shown that selectivity to ethane, the Kolbe product, strongly depends on the shape and geometry of the platinum particles. Using nano-thorn-like Pt particles, a faradaic efficiency of approx. 40% towards ethane can be obtained, whereas 3D porous platinum nanoparticles showed high selectivity towards the OER. Using thin platinum layers, a high FE of >70% towards ethane was obtained, which is thickness-independent at layer thicknesses above 20 nm. Comparison with other substrates revealed that BDD is an ideal support for Pt functionalisation, giving advantages of stability and high-value-product formation (ethane and methanol). In short, this work provides guidelines for electrode fabrication in the context of the electrochemical upgrading of biomass feedstocks by acid decarboxylation.

Bridging Electrochemistry and Ultrahigh Vacuum: "Unburying" the Electrode-Electrolyte Interface

ConspectusElectrochemistry has a central role in addressing the societal issues of our time, including the United Nations' Sustainable Development Goals (SDGs) and beyond. At a more basic level, however, elucidating the nature of electrode-electrolyte interfaces is an ongoing challenge due to many reasons, but one obvious reason is the fact that the electrode-electrolyte interface is buried by a thick liquid electrolyte layer. This fact would seem to preclude, by default, the use of many traditional characterization techniques in ultrahigh vacuum surface science due to their incompatibility with liquids. However, combined UHV-EC (ultrahigh vacuum-electrochemistry) approaches are an active area of research and provide a means of bridging the liquid environment of electrochemistry to UHV-based techniques. In short, UHV-EC approaches are able to remove the bulk electrolyte layer by performing electrochemistry in the liquid environment of electrochemistry followed by sample removal (referred to as emersion), evacuation, and then transfer into vacuum for analysis.Through this Account, we highlight our group's activities using UHV-EC to bridge electrochemistry with UHV-based X-ray and ultraviolet photoelectron spectroscopy (XPS/UPS) and scanning tunneling microscopy (STM). We provide a background and overview of the UHV-EC setup, and through illustrative examples, we convey what sorts of insights and information can be obtained. One notable advance is the use of ferrocene-terminated self-assembled monolayers as a spectroscopic molecular probe, allowing the electrochemical response to be correlated with the potential-dependent electronic and chemical state of the electrode-monolayer-electrolyte interfacial region. With XPS/UPS, we have been able to probe changes in the oxidation state, valence structure, and also the so-called potential drop across the interfacial region. In related work, we have also spectroscopically probed changes in the surface composition and screening of the surface charge of oxygen-terminated boron-doped diamond electrodes emersed from high-pH solutions. Finally, we will give readers a glimpse into our recent progress regarding real-space visualizations of electrodes following electrochemistry and emersion using UHV-based STM. We begin by demonstrating the ability to visualize large-scale morphology changes, including electrochemically induced graphite exfoliation and the surface reconstruction of Au surfaces. Taking this further, we show that in certain instances atomically resolved specifically adsorbed anions on metal electrodes can be imaged. In all, we anticipate that this Account will stimulate readers to advance UHV-EC approaches further, as there is a need to improve our understanding concerning the guidelines that determine applicable electrochemical systems and how to exploit promising extensions to other UHV methods.

Boron-Doped Diamond Electrodes: Fundamentals for Electrochemical Applications

Boron-doped diamond (BDD) electrodes have emerged as next-generation electrode materials for various applications in electrochemistry such as electrochemical sensors, electrochemical organic synthesis, CO₂ reduction, ozone water generation, electrochemiluminescence, etc. An optimal BDD electrode design is necessary to realize these applications. The electrochemical properties of BDD electrodes are determined by important parameters such as (1) surface termination, (2) surface orientation, and (3) boron doping level.In this Account, we discuss how these parameters contribute to the function of BDD electrodes. First, control of the surface termination (hydrogen/oxygen) is described. The electrochemical conditions such as the solution pH and the application potential were studied precisely. It was confirmed that an acidic solution and the application of negative potential accelerate hydrogenation, and the mechanism behind this is discussed. For oxygenation, we directly observed changes in surface functional groups by in situ attenuated total reflection infrared spectroscopy and electrochemical X-ray photoelectron spectroscopy measurements.Next, the difference in surface orientation was examined. We prepared homoepitaxial single-crystal diamond electrodes comprising (100) and (111) facets with similar boron concentrations and resistivities and evaluated their electrochemical properties. Experimental results and theoretical calculations revealed that (100)-oriented single-crystal BDD has a wider space charge layer than (111)-oriented BDD, resulting in a slower response. Furthermore, isolated single-crystal microparticles of BDD with exposed (100) and (111) crystal facets were grown, and we studied the electrochemical properties of the respective facets by combination with hopping-mode scanning electrochemical cell microscopy.We also systematically investigated how the boron concentration and sp² species affect the electrochemical properties. The results showed that the appropriate composition (boron and sp² species level) is dependent on the application. The transmission electron microscopy images and electron energy loss spectra of highly boron-doped BDD are shown, and the relationship between the composition and electrochemical properties is discussed. Finally, we investigated in detail the effect of the sp² component on low-doped BDD. Surprisingly, although the sp² component is usually expected to induce a narrowing of the potential window and an increase in the charging current, low-doped BDD showed the opposite trend depending on the degree of sp² carbon.The results and discussion presented in this Account will hopefully promote a better understanding of the fundamentals of BDD electrodes and be useful for the optimal development of electrodes for future applications.

Epitaxial Self-Assembly of Interfaces of 2D Metal-Organic Frameworks for Electroanalytical Detection of Neurotransmitters

This paper identifies the electrochemical properties of individual facets of anisotropic layered conductive metal-organic frameworks (MOFs) based on M3(2,3,6,7,10,11-hexahydroxytriphenylene)2 (M3(HHTP)2) (M = Co, Ni). The electroanalytical advantages of each facet are then applied toward the electrochemical detection of neurochemicals. By employing epitaxially controlled deposition of M3(HHTP)2 MOFs on electrodes, the contribution of the basal plane ({001} facets) and edge sites ({100} facets) of these MOFs can be individually determined using electrochemical characterization techniques. Despite having a lower observed heterogeneous electron transfer rate constant, the {001} facets of the M3(HHTP)2 systems prove more selective and sensitive for the detection of dopamine than the {100} facets of the same MOF, with the limit of detection (LOD) of 9.9 ± 2 nM in phosphate-buffered saline and 214 ± 48 nM in a simulated cerebrospinal fluid. Langmuir isotherm studies accompanied by all-atom MD simulations suggested that the observed improvement in performance and selectivity is related to the adsorption characteristics of analytes on the basal plane versus edge sites of the MOF interfaces. This work establishes that the distinct crystallographic facets of 2D MOFs can be used to control the fundamental interactions between analyte and electrode, leading to tunable electrochemical properties by controlling their preferential orientation through self-assembly.

Degradation of Perfluorooctanoic Acid with Hydrated Electron by a Heterogeneous Catalytic System

Hydrated electron (e_aq^-)-induced reduction protocols have bright prospects for the decomposition of recalcitrant organic pollutants. However, traditional e_aq^- production involves homogeneous sulfite photolysis, which has a pH-dependent reaction activity and might have potential secondary pollution risks. In this study, a heterogeneous UV/diamond catalytic system was proposed to decompose of a typical persistent organic pollutant, perfluorooctanoic acid (PFOA). In contrast to the rate constant of the advanced reduction process (ARP) of a UV/SO₃^2-, the k_obs of PFOA decomposition in the UV/diamond system showed only minor pH dependence, ranging from 0.01823 ± 0.0014 min^-1 to 0.02208 ± 0.0013 min^-1 (pH 2 to pH 11). As suggested by the electron affinity (EA) and electron configuration of the diamond catalyst, the diamond catalyst yields facile energetic photogenerated electron emission into water without a high energy barrier after photoexcitation, thus inducing e_aq^- production. The impact of radical scavengers, electron spin resonance (ESR), and transient absorption (TA) measurements verified the formation of e_aq^- in the UV/diamond system. The investigation of diamond for ejection of energetic photoelectrons into a water matrix represents a new paradigm for ARPs and would facilitate future applications of heterogeneous catalytic processes for efficient recalcitrant pollutant removal by e_aq^-.

Advances in RF Glow Discharge Optical Emission Spectrometry Characterization of Intrinsic and Boron-Doped Diamond Coatings

Accurate determination of the effective doping range within diamond thin films is important for fine-tuning of electrical conductivity. Nevertheless, it is not easily attainable by the commonly adopted techniques. In this work, pulsed RF glow discharge optical emission spectrometry (GD-OES) combined with ultrafast sputtering (UFS) is applied for the first time to acquire elemental depth profiles of intrinsic diamond coatings and boron content bulk distribution in films. The GD-OES practical advances presented here enabled quick elemental profiling with noteworthy depth resolution and determination of the film interfaces. The erosion rates and layer thicknesses were measured using differential interferometric profiling (DIP), demonstrating a close correlation between the coating thickness and the carbon/hydrogen gas ratio. Moreover, DIP and the adopted semiquantification methodology revealed a nonhomogeneous bulk distribution of boron within the diamond crystalline structure, i.e., boron doping is both substitutional and interstitial within the diamond framework. DIP measurements also showed that effective boron doping is not linearly correlated to the increasing content introduced into the diamond coating. This is a finding well supported by X-ray diffraction (XRD) Rietveld refinement and X-ray photoelectron spectroscopy (XPS). This work demonstrates the advantage of applying advanced GD-OES operation modes due to its ease of use, affordability, accuracy, and high-speed depth profile analysis capability.

Study of Tribological Properties of Fullerenol and Nanodiamonds as Additives in Water-Based Lubricants for Amorphous Carbon (a-C) Coatings

The tribological performances of fullerenol and nanodiamonds (NDs) as additives in water-based lubricants for amorphous carbon (a-C) coatings are investigated to avoid disadvantage factors, such as chemical reactions and deformation of particles. The effects of size and additive amount on tribological properties of nanoparticles are studied by rigid nanoparticles within the dot size range. The results show that owing to its small particle size (1-2 nm), fullerenol cannot prevent direct contact of the friction pair at low concentration conditions. Only when the quantity of fullerenol increased to support the asperity contact loads in sufficient concentration did nano-bearings perform well in anti-friction and anti-wear effects. Unlike fullerenol, nanodiamond particles with a diameter of about 5-10 nm show friction-reducing effect based on the nano-bearing effects at ultra-low concentration (0.01 wt.%), whereas particles at higher concentration block the rolling movement, hence increasing the coefficient of friction (COF) and wear. As a result of the effect of difference in size, fullerenol provides a better overall lubrication, but it is hard to reach a friction coefficient as low as NDs even under the optimal conditions.

A Dual Approach of an Oil-Membrane Composite and Boron-Doped Diamond Electrode to Mitigate Biofluid Interferences

Electrochemical biosensors promise a simple method to measure analytes for both point-of-care diagnostics and continuous, wearable biomarker monitors. In a liquid environment, detecting the analyte of interest must compete with other solutes that impact the background current, such as redox-active molecules, conductivity changes in the biofluid, water electrolysis, and electrode fouling. Multiple methods exist to overcome a few of these challenges, but not a comprehensive solution. Presented here is a combined boron-doped diamond electrode and oil–membrane protection approach that broadly mitigates the impact of biofluid interferents without a biorecognition element. The oil–membrane blocks the majority of interferents in biofluids that are hydrophilic while permitting passage of important hydrophobic analytes such as hormones and drugs. The boron-doped diamond then suppresses water electrolysis current and maintains peak electrochemical performance due to the foulant-mitigation benefits of the oil–membrane protection. Results show up to a 365-fold reduction in detection limits using the boron-doped diamond electrode material alone compared with traditional gold in the buffer. Combining the boron-doped diamond material with the oil–membrane protection scheme maintained these detection limits while exposed to human serum for 18 h.

Phenolic water toxins: redox mechanism and method of their detection in water and wastewater

Phenolic pollutants are highly toxic and persistent in the environment. Their efficient detection is a pressing social demand. In this regard we introduce a novel ultrasensitive electroanalytical platform for the individual and synchronized detection of three phenolic isomers commonly known as hydroquinone (HQ), resorcinol (RC), and catechol (CC). The sensing device consists of a glassy carbon electrode (GCE) modified with functionalized carbon nanotubes (fCNTs) and gold-silver (Au-Ag NPs) bimetallic nanoparticles. The sandwiched scaffold represented as fCNTs/Au-Ag NPs/fCNTs/GCE efficiently senses HQ, RC, and CC with detection limits of 28.6 fM, 36.5 fM and 42.8 fM respectively. The designed sensor is more promising than reported sensors for phenolic toxins in the context of high sensitivity, selectivity, and rapid responsiveness. The designed sensor also shows the qualities of stability, reproducibility, reliability, and selective recognition capacity for target analytes in multiple real water samples. Moreover, computational calculations explain the function of the electrode modifier in facilitating charge transfer between the transducer and analytes.

Electrochemical sensing platform for the simultaneous femtomolar detection of amlodipine and atorvastatin drugs

The development of a proficient and ultra-high sensitive functionalized electrode for accurate analysis of drugs is a long-standing challenge. Herein, we report an electrochemical nanocomposite scaffold, comprising of silver nanoparticles integrated with functionalized carbon nanotubes (COOH-CNTs/Ag/NH₂-CNTs) for the simultaneous quantification of two widely used amlodipine (AM) and atorvastatin (AT) drugs. The sandwiched nanocomposite materials were thoroughly characterized morphologically and structurally. The nanocomposite COOH-CNTs/Ag/NH₂-CNTs immobilized over glassy carbon electrode catalyzed electron transfer reactions at the electrode–electrolyte interface and facilitated detection of targeted drugs, as revealed by the significant decrease in oxidation potentials at 879 mV and 1040 mV and improved current signals. Electrochemical characterization and testing show that the functionalized porous architecture with a large effective surface area is a promising scaffold for the sensing of a binary mixture of AM and AT with limits of detection in the femtomolar range (77.6 fM, and 83.2 fM, respectively). Besides, the specificity, stability, and reliability of the electrochemical sensing platform in simple and complex biological and pharmaceutical samples with high percentage recoveries highlight its scope for practical applications. Computational studies supported the experimental outcomes and offered insights about the role of modifier in facilitating electron transfer between transducer and analytes.

Development of an ultra-sensitive electrochemical platform for the simultaneous detection of two high blood pressure drugs.

Reversible Proton-Coupled Reduction of an Iron Nitrosyl Porphyrin within [DBU-H]+-Based Protic Ionic Liquid Nanodomains

The reduction of [Fe(OEP)(NO)] has been studied in the presence of aprotic room-temperature ionic liquids (RTIL) and protic (PIL) ionic liquids dissolved within a molecular solvent (MS). The cyclic voltammetric results showed the formation of RTIL nanodomains at low concentrations of the RTIL/PIL solutions. The pK_a values of the two PILs studied (i.e., trialkylammonium and [DBU-H]⁺-based ionic liquids) differed by four units in THF. While voltammetry in solutions containing all three RTILs showed similar potential shifts of the first reduction of [Fe(OEP)(NO)] to [Fe(OEP)(NO)]^- at low concentrations, significant differences were observed at higher concentrations for the ammonium PIL. The trialkylammonium cation had previously been shown to protonate the {FeNO}⁸ species at room temperature. Visible and infrared spectroelectrochemistry revealed that the [DBU-H]⁺-based PIL formed hydrogen bonds with [Fe(OEP)(NO)]^- rather than formally protonating it. Despite these differences, both PILs were able to efficiently reduce the nitrosyl species to the hydroxylamine complex, which could be further reduced to ammonia. On the voltammetric time scale and when the switching potential was positive of the Fe(II)/Fe(I) potential, the hydroxylamine complex was re-oxidized back to the NO complex via direct oxidation of the coordinated hydroxylamine at low scan rates or initial oxidation of the ferrous porphyrin at high scan rates. The results of this work show that, while [DBU-H]⁺ does not protonate electrochemically generated [Fe(OEP)(NO)]^-, it still plays an important role in efficiently reducing the nitroxyl ligand via a series of proton-coupled electron transfer steps to generate hydroxylamine and eventually ammonia. The overall reaction rates were independent of the PIL concentration, consistent with the nanodomain formation being important to the reduction process.

Assessment of the use of boron-doped diamond electrode for highly sensitive voltammetric determination of the azo-dye carmoisine E-122 in food and environmental matrices

A new protocol for the analysis of the azo-dye carmoisine (CMS) is presented by coupling differential pulse voltammetry (DPV) with a cathodically pretreated boron-doped diamond electrode (CPT-BDDE), in phosphate buffer solution (pH 2.0). The CMS presented diffusion-controlled oxidation and reduction peaks at +0.88 and -0.15 V vs Ag/AgCl, respectively. The effect of the pretreatment conditions, pH, and supporting electrolytes were evaluated to the voltammetric determination of CMS. Under optimized conditions, the differential pulse voltammetric signals for CMS were linear over the concentration range of 0.059-1.31 μmol L^-1 and 0.010-0.079 μmol L^-1 with limits of detection of 7.0 and 3.0 nmol L^-1, for the anodic and cathodic processes respectively. The method was precise for CMS determination (RSD < 5.0%) and selective against other dyes. The developed protocol was successfully applied in the analysis of CMS in surface water and foodstuffs with accurate results in comparison with those obtained using a validated spectrophotometric method.

Electrode Materials in Modern Organic Electrochemistry

The choice of electrode material is critical for achieving optimal yields and selectivity in synthetic organic electrochemistry. The material imparts significant influence on the kinetics and thermodynamics of electron transfer, and frequently defines the success or failure of a transformation. Electrode processes are complex and so the choice of a material is often empirical and the underlying mechanisms and rationale for success are unknown. In this review, we aim to highlight recent instances of electrode choice where rationale is offered, which should aid future reaction development.

A Review on Recent Advances in the Applications of Boron-Doped Diamond Electrochemical Sensors in Food Analysis

The usage of boron-doped diamond (BDD) material has found to be very attractive in modern electroanalytical methods and received massive consideration as perspective electrochemical sensor due to its outstanding (electro)chemical properties. These generally known facilities include large potential window, low background currents, ability to withstand extreme potentials and strong tendency to resist fouling compared to conventional carbon-based electrodes. As evidence of superiority of this material, couple of reviews describing the overview of various applications of BDD electrodes in the field of analytical and material chemistry has been reported in scientific literature during last decade. However, herein proposed review predominantly focuses on the most recent developments (from 2009 to 2020) dealing with the application of BDD as an advanced and environmental-friendly sensor platform in food analysis. The main method characteristics of analysis of various organic food components with different chemical properties, including additives, flavor and aroma components, phenolic compounds, flavonoids and pesticides in food matrices are described in more details. The importance of BDD surface termination, presence of sp² content and boron doping level on electrochemical sensing is discussed. Apart from this, a special attention is paid to the evaluation of main analytical characteristics of the BDD electrochemical sensor in single- and multi-analyte detection mode in food analysis. The recent achievements in the utilizing of BDD electrodes in amperometric detection coupled to flow injection analysis, batch injection analysis, and high-performance liquid chromatography are also commented. Moreover, actual trends in sample preparation techniques prior to electrochemical sensing in food analysis are referred.

Electro-organic synthesis - a 21st century technique

The severe limitations of fossil fuels and finite resources influence the scientific community to reconsider chemical synthesis and establish sustainable techniques. Several promising methods have emerged, and electro-organic conversion has attracted particular attention from international academia and industry as an environmentally benign and cost-effective technique. The easy application, precise control, and safe conversion of substrates with intermediates only accessible by this method reveal novel pathways in synthetic organic chemistry. The popularity of electricity as a reagent is accompanied by the feasible conversion of bio-based feedstocks to limit the carbon footprint. Several milestones have been achieved in electro-organic conversion at rapid frequency, which have opened up various perspectives for forthcoming processes.