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The electrochemical oxidation of hydroxide ions using boron-doped diamond (BDD) electrodes in weak basic solutions was examined. Using simple linear sweep voltammetry (LSV), a well-shaped peak originating from the oxidation of hydroxide ions involving a CE mechanism was observed at ∼1.30 V versus a Ag/AgCl reference electrode in 20 mM H3PO4 solutions with hydroxide ion concentrations ranging from 0.1 to 10 mM. Compared to a NaOH solution with the same hydroxide ion concentration, the peak current in the phosphate solution was found to be higher due to the buffering capability of the phosphate solution, which maintains the hydroxide ion concentration, making it possible to provide more hydroxide ions to the surface of the electrode. The peak was found to depend not only on the hydroxide ion concentration, but also on the phosphate concentration, confirming that the origin of the peak was due to oxidation of the hydroxide ions enhanced by the buffering capability of the weak basic solution. These results further promote the use of BDD electrodes for measuring hydroxide ion concentration, and offer the possibility of directly measuring the buffer capacity of a solution.

We have developed a new method for fabricating all-diamond microelectrodes. The process comprises three steps: masking the tip of an electrode by electroplating with chromium, depositing undoped diamond, which acts as an insulator on the sides of the electrode, and removing the chromium mask to expose the tip of the electrode. The active area of the electrode can be easily controlled in combination only with a conventional electroplating technique.

It is well known that “diamond” has ultra-high hardness and low electrical conductivity. However, introducing dopants such as boron into the diamond lattice during growth can increase its conductiv...

Natural products have played a significant role not only in discovery of drugs but also in development of organic chemistry by providing the synthetic challenges. Inspired by biosynthesis where enzymes catalyze a multi-step reaction, we have investigated the natural product synthesis utilizing electrochemical reactions as the key step. Electrochemical organic synthesis, so-called electro-organic synthesis, enables to control the reactivity of substrates simply by tuning electrolysis conditions. In this Personal Account, we overview the recent progress of our research projects about natural product synthesis, in which anodic oxidation of phenol compounds affords the important frameworks such as diaryl ether, spirodienone, and spiroisoxazoline.

Nanodiamonds (NDs) are a type of biocompatible nanomaterial with easily modified surfaces and are considered as promising candidates in biomedicine. In this work, the inhibition of tumor cell migration by carboxylated nanodiamonds (cNDs) was investigated. AFM-based single cell adhesion and F-actin staining experiments demonstrated that cNDs treatment could enhance cell adhesion and impair assembly of the cytoskeleton. The mechanism analysis of the regulatory protein expression level also proved that cNDs could inhibit the migration of Hela cells by preventing the epithelial-mesenchymal transition (EMT) process through the transforming growth factor β (TGF-β) signaling pathway. The in vivo pulmonary metastasis model also showed that cNDs effectively reduced the metastasis of murine B16 melanoma cells. In summary, cNDs have been demonstrated to inhibit cancer cell migration in vitro and decrease tumor metastasis in vivo. Therefore, cNDs might have potential utility for specific cancer treatment.

The coercivity of magnetic nanoparticles is enhanced by the exchange coupling effect at the interface of ferrimagnetic and antiferromagnetic self-assembled monolayers. Antiferromagnetic Co3O4 nanocubes were regularly stacked on an ordered monolayer of ferrimagnetic Fe3O4 nanocubes by layer-by-layer manipulation using evaporation-driven self-assembly. The ordered arrangements of the ferrimagnetic and antiferromagnetic nanocubes are effective for the enhancement of the ferromagnetic character. published

We report the development of a micro total analysis system (μTAS) based on electrochemical measurements and dielectrophoretic sorting for screening of NAD(P)-dependent oxidoreductases. In this system, the activity of enzymes immobilized on microbeads, together with their encoding DNA, can be measured with a boron-doped diamond (BDD) electrode in each compartment (∼30 nL) of the microfluidic system. The 30 nL droplets containing microbead-displayed genes of enzymes with higher activity can then be recovered by dielectrophoretic sorting. Previously, we developed the NAD(P)H-measuring device containing the BDD electrode for high-throughput measurement of the activity of NAD(P)-dependent oxidoreductases. In this study, we fabricated an encapsulating device and a droplet-sorting device for nanoliter-size droplets, for the first time, and then combined these three devices to construct a μTAS for directed evolution of NAD(P)-dependent oxidoreductases. We confirmed that this system works by proof-of-principle experiments and successfully applied this system for screening of randomized libraries of NAD-dependent dehydrogenases.

Unexpected phenomena displayed by low-boron-doped diamond (BDD) electrodes are disclosed in the present work. Generally, the presence of sp

The electrochemical nitrate reduction by using boron-doped diamond (BDD) and copper modified boron-doped diamond (Cu-BDD) electrodes was investigated at various potentials. Nitrate reduction efficiency and the products distribution was strongly dependent on the applied potential for both electrodes. The highest nitrate reduction efficiency of 77% was obtained at −2.0 V (vs. Ag/AgCl) by using Cu-BDD. Compared with BDD electrode, nitrate reduction on Cu-BDD electrode occurred at more positive potential. Copper oxides formed on BDD surface efficiently promoted enhanced conductivity of electrode to promote electrons transfer during nitrate reduction process. Meanwhile, the catalytic ability of copper was also conductive to the nitrate transformation. Therefore, the developed Cu-BDD would be a promising approach for efficient nitrate removal from groundwater.

High concentrations of CO2 in the atmosphere may cause climate and environmental changes. Therefore, various research has been extensively performed to reduce CO2 by converting CO2 directly into hydrocarbons. In this research, CO2 electrochemical reduction was studied using boron-doped diamond (BDD) modified with copper nanoparticles to improve BDD electrodes’ catalytic properties. The deposition was performed by chronoamperometry technique at a potential of -0.6 V (vs. Ag/AgCl) and characterized using SEM, EDS, XPS, and cyclic voltammetry (CV). CO2 electrochemical reduction on BDD and Cu-BDD was carried out at -1.5 V (vs. Ag/AgCl) for 60 minutes. The products were analyzed using HPLC and GC. The product was mainly formic acid with a concentration of 11.33 mg/L and 33% faradaic efficiency on a Cu-BDD electrode.

Electrochemical surface oxidation in acidic solutions was investigated on a boron-doped diamond film electrode, fabricated on a silicon prism, using attenuated total reflection infrared spectroscopy. At positive potentials above +1.3 V (reversible hydrogen electrode, RHE), the bands of surface oxygen species appear at 1745 and 1250 cm–1. Since these bands exhibit no isotope shift in deuterium solution, they are assigned to the C═O and C–O stretching modes, respectively. These bands have the maximum intensity at +3.3 V (RHE) and reversibly disappear around +0.9 V (RHE) in the potential step to the negative direction. The potentials at which the bands appear and disappear are identical to those of the anodic and cathodic peaks of the cyclic voltammogram, respectively.

The electrochemical nitrate reduction by using boron-doped diamond (BDD) and copper (Cu) electrodes was investigated at various potentials. Product selectivity of nitrate reduction was strongly dependent on the applied potential for both electrodes. The highest selectivity of nitrogen gas production was obtained at −2.0 V (vs. Ag/AgCl) by using a BDD electrode with a faradaic efficiency as high as 45.2%. Compared with Cu electrode, nitrate reduction on BDD electrode occurred at more positive potential, and the production of nitrogen gas was larger. The transformation of surface-adsorbed nitrate into molecular nitrogen would be accelerated on BDD electrode with hindering nitrite production. In addition, low concentration of surface-adsorbed hydrogen on the BDD would also retard the ammonia generation, leading to increase in the selectivity of nitrogen gas formation. Meanwhile, BDD electrode could hinder the hydrogen evolution reaction, which enhanced the efficiency for nitrate reduction and decreased energy consumption. BDD electrode has excellent stability to remain better performance for reducing nitrate during electrolysis without any variation of surface morphology or chemical components.

Transmission electron microscopy (TEM) coupled with electron energy loss spectroscopy (EELS), and first principles calculations of EEL spectra were utilized to elucidate the relationship between the microscopic structure and the electrochemical properties of heavily boron-doped diamond (h-BDD). The electrochemical properties of h-BDD containing 1 at.% and 3 at.% boron are very different. TEM observations showed that 1 at.% h-BDD consists of small densely packed diamond crystallites, while 3 at.% h-BDD contains small voids and a graphite phase partly along the grain boundaries. The EEL spectrum of the grain interior in 1 at.% h-BDD and comparison of this with a theoretical spectrum shows that the boron atoms are mostly dispersed as single isolated substitutional atoms on diamond lattice sites in the grain interior and that only a small amount of sp2-bonded carbon is present. In contrast, in the grain interior of 3 at.% h-BDD, the boron atoms are mostly associated with nearest neighbor boron pairs, and consequently sp2-bonded carbon is formed. Thus, the local structure has a significant effect on the amount of sp2-bonded carbon. The quite different electrochemical properties of the samples are ascribed to the amount of sp2-bonding arising from the different local structures.

This study is among the first to systematically study the electrochemical reduction of nitrate on boron-doped diamond (BDD) films with different surface terminations and boron-doping levels. The highest nitrate reduction efficiency was 48% and the highest selectivity in the production of nitrogen gas was 44.5%, which were achieved using a BDD electrode with a hydrogen-terminated surface and a B/C ratio of 1.0%. C-H bonds served as the anchor points for attracting NO3- anions close to the electrode surface, and thus accelerating the formation of NO3-(ads). Compared to oxygen termination, hydrogen-terminated BDD exhibited higher electrochemical reactivity for reducing nitrate, resulting from the formation of shallow acceptor states and small interfacial band bending. The hydrophobicity of the hydrogen-terminated BDD inhibited water electrolysis and the subsequent adsorption of atomic hydrogen, leading to increased selectivity in the production of nitrogen gas. A BDD electrode with a boron-doping level of 1.0% increased the density of acceptor states, thereby enhancing the conductivity and promoting the formation of C-H bonds after the cathodic reduction pretreatment leading to the direct reduction of nitrate.

The study of CO

The long-term durability of boron-doped diamond electrodes (BDD) used continuously in the electrochemical conversion of CO2 to formic acid was investigated. Although the Faradaic efficiency (FE) for the production of formic acid decreased with increasing electrolysis time, the FE was easily recovered by electrochemical oxidation of the BDD electrodes in H2SO4, Na2SO4 or K2SO4 solutions. For practical application, the long-term production of formic acid using BDD electrodes can be successfully accomplished just by successive polarity reversal of plus and minus terminals. Furthermore, at a current density of −20 mA cm–2, the rate of production reached 328 μmol h–1 cm–2, which is the highest value ever obtained using plate electrodes. Consequently, we found that BDD electrodes are ideal for industrial application of CO2 reduction.

In this paper we report on a study of the electrochemical behavior of lamotrigine (LTG) using boron-doped diamond (BDD) electrodes. Cyclic voltammetry of LTG in a phosphate buffer solution exhibited an oxidation signal at ca. +1.4 V (vs. Ag/AgCl). A reduction signal at −0.5 to −1.0 V (vs. Ag/AgCl) was observed only after oxidation of LTG. The oxidation signal was due to polymerization of LTG adsorbed on the BDD electrode, while the reduction signal was a consequence of a process involving the reduction of the azo group in the LTG-oxidized product. Continuous measurements of LTG aiming at in vivo monitoring were successfully investigated and an optimized chronoamperometry technique, in which the BDD microelectrode was clamped to the LTG oxidation potential (+1.4 V) for 2 s, then to the LTG reduction potential (−0.6 V) for 2 s, was implemented. The limits of detection (S/N = 3) were estimated to be 29 nM and 130 nM for the oxidation and reduction of LTG, respectively. The use of this chronoamperometry technique enables a high temporal resolution of 4 s for LTG measurements. BDD microelectrodes, therefore, are the ideal electrodes for performing continuous in vivo measurements of LTG.

Controlled surface functionalization of electrode materials is an important technique in various fields such as analytical chemistry, molecular electronics, and molecular recognition in biological systems. In this work, we report the control decoration of boron-doped diamond (BDD) electrodes by electrochemically driven copper(I)-catalyzed Huisgen 1,3-dipolar cycloaddition of alkyne and azide (e−CLICK) in which the catalyst is produced by electroreduction of copper(II) species. As the e−CLICK strategy enabled to tune the produced amount of the copper(I) catalyst electrochemically, the alkyne-terminated BDD electrodes were decorated with azide-terminated ferrocene in a controlled manner.

We report on the first observation of the production of C2/C3 species from the electrochemical reduction of CO2 at the surfaces of copper-modified boron-doped diamond (Cu-BDD) electrodes in aqueous media at room temperature and ambient pressure. The product distribution is dependent on the amount of deposited Cu and the applied potential. At low potential, −1.0 V (vs. Ag/AgCl), ethanol was observed as the main product with acetaldehyde and acetone as side products. The highest faradaic efficiencies obtained for ethanol, acetaldehyde and acetone were 42.4%, 13.7% and 7%, respectively. The Cu particles on the surfaces of the BDD electrodes remained stable, showing insignificant differences after the CO2 electroreduction process under these particular conditions. The efficiency dropped with increasing Cu deposition time and at high reduction potentials. Moreover, we present comparisons with a Cu plate and Cu-modified glassy carbon as working electrodes under the same conditions, which explains the specific behavior of the CO2 reduction process on the Cu-BDD electrode.

A Series of [Fe-II(L)(2)](BF4)(2) compounds were structurally and physically characterized (L = 2,6-bis(2-methylthiazol-4-yl)pyridine). A crystal structure phase transformation from dihydtate compound 1 to anhydrous compound 3 through partially hydrated compounds 2 and 2' upon dehydration was found. Compounds 1 and 3 exhibited a gradual spin crossover (SCO) conversion, whereas compounds 2 and 2' demonstrated two-step and one-step abrupt SCO transitions, respectively. An X-ray single-crystal structural analysis revealed that one-dimensional and two-dimensional Fe cation networks linked by π stacking and sulfur-sulfur interactions. Were formed in 1 and 3, respectively. A thermodynamic analysis of the magnetic susceptibility for 1, 2', and 3 suggests that the enthalpy differences may govern SCO transition behaviors in the polymorphic compounds 2' and 3. A structural comparison between 1 and 3 indicates that the SCO behavior variations and crystal structure transformation in the present [Fe-II(L)(2)](BF4)(2) compounds can be interpreted by the relationship between the lattice enthalpies mainly arising froth Coulomb interactions between the Fe cations and BF4 anions as in typical ionic crystals.

Boron-doped diamond (BDD) electrodes are being increasingly investigated for application to electrochemical CO2 reduction. Previous, studies have mainly focused on microcrystalline (MC) BDD electrodes. In our study, we present an analysis of electrochemical CO2 reduction using sub-microcrystalline (SMC) BDD electrodes with different boron doping concentrations (0.28%, 0.11% and 0.03%). Unlike the microcrystalline case, these synthetic SMC BDD films with high sp2-bonded carbon do not show a boron-concentration dependence in terms of the activity of CO2 reduction to form formic acid (HCOOH). All the electrodes enabled efficient CO2 reduction at close to the maximum Faradaic efficiency for HCOOH in the range of 70% to 80%. From our observations, it is suggested that the sp2-bonded carbon should be crucial for the CO2 reduction. The results are hoped to enable a relaxation on the restrictions on the use of BDD electrodes towards industrial CO2 reduction application.

The enormous demand for medical diagnostics has encouraged the fabrication of high- performance sensing platforms for the detection of glucose. Nonenzymatic glucose sensors are coming ever closer to being used in practical applications. Bimetallic catalysts have been shown to be superior to single metal catalysts in that they have greater activity and selectivity. Here, we demonstrate the preparation, characterization, and electrocatalytic characteristics of a new bimetallic Pt/Au nanocatalyst. This nanocatalyst can easily be synthesized by electrodeposition by sequentially depositing Au and Pt on the surface of a boron-doped diamond (BDD) electrode. We characterized the nanocatalyst by scanning electron microscopy (SEM), X-ray diffraction (XRD), and voltammetry. The morphology and composition of the nanocatalyst can be easily controlled by adjusting the electrodeposition process and the molar ratio between the Pt and Au precursors. The electrocatalytic characteristics of a Pt/Au/BDD electrode for the nonenzymatic oxidation of glucose were systematically investigated by cyclic voltammetry. The electrode exhibits higher catalytic activity for glucose oxidation than Pt/BDD and Au/BDD electrodes. The best catalytic activity and stability was obtained with a Pt:Au molar ratio of 50:50. Moreover, the presence of Au can significantly enhance the long-term stability and poisoning tolerance during the electro-oxidation of glucose. Measurements of glucose using the Pt/Au/BDD electrode were linear in the range from 0.01 to 7.5mM, with a detection limit of 0.0077mM glucose. The proposed electrode performs selective electrochemical analysis of glucose in the presence of common interfering species (e.g., acetaminophen, uric and ascorbic acids), avoiding the generation of overlapping signals from such species.

The carbon-based electrode has been widely used for electrochemical analysis and synthesis. It is relatively inert for hydrogen evolution in the negative potential range, which is suitable for CO2 electrochemical reduction. In improving the catalytic activity, a modification of metal particles is commonly used on its surface. Various metal particles have been reported with multiple modification methods, including electrochemical and physical methods. In this report, the utilization of different metal particles, including metal oxide, metal hydroxide, and metal complexes, which are modified on carbon-based electrodes for CO2 electrochemical reduction application is specifically reviewed. This review is expected to provide comprehensive information on related topics.

The electrochemical CO2 reduction on boron-doped diamond (BDD) electrodes in an aqueous solution with fine bubbles was studied. The overpotential decreased and the production of carbon monoxide was promoted in the CO2 reduction with fine bubbles compared to that without fine bubbles. It is suggested that fine bubbles in solution could facilitate the mass transport and also act as the catalyst for producing carbon monoxide. Potential-dependent in-situ attenuated total reflectance-infrared (ATR-IR) measurements confirmed the catalytic activity, showing that in solutions with CO2 fine bubbles the CO2•– intermediate or the CO2 molecules themselves become stabilized near the electrode and these can be adsorbed on the electrode surface more easily compared to using solutions without CO2 fine bubbles. The reported work is a first step in understanding the effects of fine bubbles in CO2 reduction reactions.

The progression of corrosion in polycrystalline boron-doped diamond (BDD) thin film electrode is explored as the electrode undergoes high-current density anodic treatments with organic compounds. Micro-Raman spectroscopy and spectral mapping indicate that anodic corrosion is initiated by the conversion of sp3 diamond to amorphous sp2 carbon at the surface, which are then removed after longer anodic treatment. Polarized Raman analysis reveals that corrosion-induced changes on the surface are specific to (100)-grain facets and (111)-grain edges. X-ray photoelectron spectroscopic measurements suggest that carbonyl groups consequently form on these specific sites and act as an intermediate toward the etching of the surface. This process exposes and subsequently removes the subsurface boron atoms, thus reducing the doping density. The observed crystal grain orientation dependence of the corrosion process provides new insights toward a better understanding of degradation in BDD electrodes.

Real-time recording of the kinetics of systemically administered drugs in in vivo microenvironments may accelerate the development of effective medical therapies. However, conventional methods require considerable analyte quantities, have low sampling rates and do not address how drug kinetics correlate with target function over time. Here, we describe the development and application of a drug-sensing system consisting of a glass microelectrode and a microsensor composed of boron-doped diamond with a tip of around 40 μm in diameter. We show that, in the guinea pig cochlea, the system can measure—simultaneously and in real time—changes in the concentration of bumetanide (a diuretic that is ototoxic but applicable to epilepsy treatment) and the endocochlear potential underlying hearing. In the rat brain, we tracked the kinetics of the drug and the local field potentials representing neuronal activity. We also show that the actions of the antiepileptic drug lamotrigine and the anticancer reagent doxorubicin can be monitored in vivo. Our microsensing system offers the potential to detect pharmacological and physiological responses that might otherwise remain undetected. A system consisting of a glass microelectrode and a boron-doped diamond microsensor can simultaneously track, in rat brains and in the guinea pig cochlea, the local real-time kinetics of injected drugs and the resulting electrophysiological activity.

The electrochemical oxidation behavior of hydroxide ions at the surface of boron-doped diamond (BDD) electrodes is presented. The hydroxide ion oxidation behavior was found to be affected by the surface conditions of the BDD electrode. Over the NaOH concentration range of 0.5-10 mM, a well-defined voltammetric wave attributed to hydroxide ion oxidation was observed at ∼1.25 V versus a Ag/AgCl reference electrode when using an anodically oxidized BDD (AO-BDD) electrode, while it was observed at around ∼1.15 V when a cathodically reduced BDD (CR-BDD) electrode was used. Although the hydroxide ion oxidation profiles were slightly different for the AO-BDD and CR-BDD electrodes, the peak currents was each found to have linear relationships with the NaOH concentration over the same range.

A novel neutral heteroleptic FeIII complex from two kinds of π-extended tridentate ligands was designed and prepared. The π-ligands formed a three-dimensional purely pi-stacking interaction network. The present complex proved to be the first neutral spin-crossover (SCO) FeIII complex with a N3O3 coordination sphere exhibiting an abrupt SCO transition with a thermal hysteresis of 10 K and the light-induced excited spin-state trapping effect.

The electrochemical reduction of carbon dioxide in aqueous solutions using boron-doped diamond (BDD) electrodes was investigated at ambient pressure and temperature. We discuss the effects of the alkali-metal (AM) cations, K+, Na+, Rb+ and Cs+, on the faradaic efficiency (FE) for the formation of formic acid. An FE of 71% was achieved in the case of a 0.075 M Rb+ solution neutralized to pH 6.2 by the addition of HCl. In the case of a Cs+ solution neutralized to pH 6.2, the highest FE was obtained with the more dilute concentration of 0.02 M. Of the four different solutions examined, the lowest FE was observed for the Na+ solution. Moreover, we found that the productivity for the production of formic acid is higher at higher current densities.

Cyclohexadienone derivatives possessing α- d -glucopyranosyl moiety were designed and synthesized using chemical oxidation or electrochemical oxidation with boron-doped diamond electrode in the final stage. In the chiral induction studies, catalytic hydrogenation provided high diastereoselectivity (dr ratio: > 9:1). Conformational analyses of the C-glucoside structures were performed by NOE experiments and force field calculations, and supported the observed regio-selectivity.

Electrolytic cells for electrochemical oxygen demand (ECOD) measurements based on total electrolytic decomposition at a boron-doped diamond (BDD) electrode were developed for rapid measurement of organic pollutants at low concentrations. Using improved electrolytic cells designed for efficient mass transfer, the ECOD for 10 μM potassium hydrogen phthalate (theoretical ECOD: 2.3 mg-O2 L-1) was determined in a relatively short electrolysis time. Thus, ECOD measurements using these cells would be useful for estimating organic water pollution in industrial waste and lake water.

This themed issue includes a collection of articles on nanocarbons.

Since a boron-doped diamond (BDD) exhibits excellent electrode properties such as wide potential window, low back-ground current, and high physical and chemical durability, it has been studied as an electrode material for various electrochemical applications. The electrochemical behavior of BDD depends on the surface termination, which can be easily converted by chemical reactions. Fluorine termination has attracted interest because it exhibits unique surface properties such as high hydrophobicity and a low coefficient of friction, and the electrochemical properties also drastically change. However, so far, it has not been elucidated why fluorinated BDD exhibits specific electrochemical properties. In this article, fluorine-terminated BDD was fabricated by a fluorine-containing plasma treatment, and the electrochemical properties were systematically investigated. Together with experiments, we have calculated the interfacial structures and electronic states of hydrogenated, oxygenated, and fluorinated BDD electrodes. As a result, fluorinated BDD showed lower electrochemical reactivity than hydrogenated and oxygenated BDD. Especially, electron transfer between anionic compound and fluorinated BDD was significantly suppressed. Considered together with theoretical calculations, this reactivity could be attributed to the larger interfacial band bending in fluorinated BDD and electrostatic interactions between BDD and redox species.

Carbon-based materials are regarded as an environmentally benign alternative to the conventional metal electrode used in electrochemistry from the viewpoint of sustainable chemistry. Among various carbon electrode materials, boron-doped diamond (BDD) exhibits superior electrochemical properties. However, it is still uncertain how surface chemical species of BDD influence the electrochemical performance, because of the difficulty in characterizing the surface species. Here, we have developed in situ spectroscopic measurement systems on BDD electrodes, i.e., in situ attenuated total reflection infrared spectroscopy (ATR-IR) and electrochemical X-ray photoelectron spectroscopy (EC-XPS). ATR-IR studies at a controlled electrode potential confirmed selective surface hydroxylation. EC-XPS studies confirmed deprotonation of C–OH groups at the BDD/electrolyte interface. These findings should be important not only for better understanding of BDD’s fundamentals but also for a variety of applications.

Ceria was deposited onto boron doped polycrystalline diamond (BDD) cathodes, through electrochemically induced precipitation from nitrate-based solutions. The deposits were characterized using SEM-EDS, HRTEM, XRD and XPS. The morphology, thickness and composition of ceria films, which besides CeO2 contained Ce(OH)(3) when prepared at very negative potential, were controlled by tuning the deposition parameters. Thin Ce(OH)(3)-free ceria films allowed CO2 electrochemical reduction at overpotentials below 50 mV, yielding formic acid with faradaic yield higher than 40% and stable performance for many hours. Ceria seemed to act as a co-catalyst that activated CO2 for reduction at the H-terminated BDD surface, because comparable results were not obtained with ceria-coated glassy carbon electrodes.

Boron-doped diamond (BDD) was modified with neighbor-paired metals; NiCu and NiMn for application in urea oxidation. The modification was conducted by a series processes, including wet chemical seeding, electrochemical overgrowth of the seeds, annealing, as well as refresh and activation techniques. Characterization was performed by using SEM and XPS showed that the method successfully deposit NiCu and NiMn on the BDD surface. However, pairing nickel with copper gave more synergic effect in lowering overpotential Ni to be Ni(OH)2 as active electrocatalyst than pairing nickel with manganese.

Nitrate contamination in groundwater requires efficient remediation to prevent adverse environmental impacts. This study illustrates the improvement in nitrate reduction process using copper modified BDD (Cu-BDD) with higher stability after annealing treatment. The highest values for nitrate reduction and the selectivity of nitrogen gas were about 71% and 45%, respectively, which were obtained using annealed Cu-BDD electrode. Annealing process promoted the homogeneity of copper oxides that consolidated the electrodeposited copper oxides on the surface of Cu-BDD to enhance the stability of electrode. Meanwhile, annealed Cu-BDD exhibited higher conductivity to facilitate nitrate reduction initiating at a more positive potential. Furthermore, cuprous ions and metallic Cu were formed during the annealing treatment, and had active chemical reaction with nitrate and excellent catalytic capability for the reaction, which efficiently enhanced either the nitrate reduction efficiency or the selectivity of nitrogen gas. The findings advance the current understanding on the enhancement of electrochemical stability and nitrate reduction performance using Cu-BDD after the annealing treatment, and also offer a promising technology for remediation of nitrate-contaminated groundwater.

The electrochemical reduction behavior of hypochlorite ions (ClO−) and hypochlorous acid (HClO) at the surface of boron-doped diamond electrodes is presented. The ClO− reduction behavior is strongly affected by the dissolved oxygen through homogeneous oxygen recovery reaction between ClO− and H2O2 as ORR product. As for HClO reduction, one-electron mechanism which is a peculiar characteristic of boron-doped diamond electrodes, was observed. Keywords: Boron-doped diamond, Free chlorine, Electrochemical sensor, Oxygen reduction reaction

The progression of influenza varies according to age and the presence of an underlying disease; appropriate treatment is therefore required to prevent severe disease. Anti-influenza therapy, such as with neuraminidase inhibitors, is effective, but diagnosis at an early phase of infection before viral propagation is critical. Here, we show that several dozen plaque-forming units (pfu) of influenza virus (IFV) can be detected using a boron-doped diamond (BDD) electrode terminated with a sialic acid-mimic peptide. The peptide was used instead of the sialyloligosaccharide receptor, which is the common receptor of influenza A and B viruses required during the early phase of infection, to capture IFV particles. The peptide, which was previously identified by phage-display technology, was immobilized by click chemistry on the BDD electrode, which has excellent electrochemical characteristics such as low background current and weak adsorption of biomolecules. Electrochemical impedance spectroscopy revealed that H1N1 and H3N2 IFVs were detectable in the range of 20-500 pfu by using the peptide-terminated BDD electrode. Our results demonstrate that the BDD device integrated with the receptor-mimic peptide has high sensitivity for detection of a low number of virus particles in the early phase of infection.