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Phase shuttling of Pb3O4 leads to the reconstructed β-PbO2 phase and significantly enhances the electrochemical ozone production (EOP) through water oxidation.

We report a chemical inactivation/redox reactivation process (IAP) based on the surface-confined rhodium–porphyrinic catalyst on a multi-walled carbon nanotube surface which presents an excellent and stable electron transfer. We used a chronoamperometric method with mathematical models and digital simulation to investigate the IAP at the catalytic metallic site. We present a mechanistic analysis of the non-catalytic and catalytic responses exhibited by this complex enabling a deep understanding of the thermodynamic and kinetic parameters that govern the IAP. These studies support a mechanism for glucose oxidation that proceeds through a complex EC′CECE scheme with catalytic steps similar to the ones reported for hydrogenases. The overall mechanism was detailed based on both electrochemical experiments and experimentally validated models. The high activity of this catalyst allows us to integrate this molecular nanomaterial in a fully molecular fuel cell together with phthalocyanine cobalt at the cathode. The resulting fuel cell reaches 0.3 mW cm−2 with a possible regeneration of initial performance.

Developing new strategies to advance the fundamental understanding of electrochemistry is crucial to mitigating multiple contemporary technological challenges. In this regard, magnetoelectrochemistry offers many strategic advantages in controlling and understanding electrochemical reactions that might be tricky to regulate in conventional electrochemical fields. However, the topic is highly interdisciplinary, combining concepts from electrochemistry, hydrodynamics, and magnetism with experimental outcomes that are sometimes unexpected. In this Review, we survey recent advances in using a magnetic field in different electrochemical applications organized by the effect of the generated forces on fundamental electrochemical principles and focus on how the magnetic field leads to the observed results. Finally, we discuss the challenges that remain to be addressed to establish robust applications capable of meeting present needs. Ministry of Education (MOE) National Research Foundation (NRF) Published version The authors thank and acknowledge support from the Singapore Ministry of Education Tier 2 Grant (MOE-T2EP10220-0001), Tier 1 Grant (RG62/21). This research was also supported by the National Research Foundation, Prime Minister’s Office, Singapore, under its Campus for Research Excellence and Technological Enterprise (CREATE) program.

Carbon-supported metal nanoparticles are widely used as electrocatalysts in polymer electrolyte membrane fuel cells (PEMFCs), but still suffer from deactivation because of metal leaching and sintering at high temperature. Herein, we propose a novel and scalable metal coordination-polymer strategy for the facile synthesis of bimetallic PdFe nanoparticles embedded nitrogen-doped carbon (PdFe@N-C) nanoframes as a Mott-Schottky electrocatalyst to efficiently catalyze the oxygen reduction reaction (ORR) in PEMFCs. The metal coordination-polymer is formed through metal ions (Pd and Fe) mediated self-polymerization of 1-naphthylamine (NA), which allows alloy nanoparticles to bind tightly with N-carbon nanoframes after pyrolysis. It is found that PdFe nanoparticles with very small particle-size are uniformly embedded in the porous N-carbon nanoframes and physically separated from each other by the carbon matrix. Profited from the unique structure and composition merits, the half-wave potential of the developed PdFe@N-C nanoframes towards ORR is positively shifted by 30 and 50 mV compared to those of Pd@N-C and Pd/C, respectively. Importantly, the PdFe@N-C nanoframes derived acidic PEMFC delivers a high-power density of 0.91 W cm⁻² together with remarkable operational stability after 10 h discharging. Such good performances make the metal-NA coordination-polymer an attractive precursor to design and synthesize high-performance electrocatalysts for fuel cells. Ministry of Education (MOE) National Research Foundation (NRF) This work was mainly supported by the AcRF Tier 1 grant (RG105/19) from Ministry of Education and the National Research Foundation (NRF), Prime Minister’s Office, Singapore under its Campus for Research Excellence and Technological Enterprise (CREATE) program in Singapore; and Natural Science Foundation of China (21875112).

Enzymatic fuel cells (EFCs) are one of the promising next-generation energy conversion systems. However, their applications are often obstructed by their power density and their lack of long-term operational stability. Enzyme immobilization is one of the strategies to overcome these limitations. The construction of a surface-confined electrode architecture that provides biocompatible microenvironments for enzyme immobilization might be a promising approach to address such barriers. Inspired by the interaction between laccase and copper ions leading to the growth of micrometer-sized flower-like particles, we successfully demonstrate a cathodic electrode design using these hybrid nanoflowers as a biocatalyst for oxygen reduction. Using this electrode architecture, enhanced activity and stability are achieved. By integrating this cathode in a fuel cell setup, two H2/O2 fuel cell configurations have been constructed: a membraneless fuel cell (MFC) and a proton exchange membrane H2/O2 fuel cell (PEMFC) that show enhancement of the performance. The cell is equipped with an oxygen-reducing laccase–Cu nanoflower/carbon nanotube biocathode and an abiotic anode. The maximum power densities of the H2/O2 MFC and PEMFC were 52 μW cm−2 and 0.41 mW cm−2, respectively. Remarkably, the H2/O2 PEMFC system maintained ∼85% of its initial power density for 15 days at room temperature, which was greatly improved when compared with previous fuel cells with different nanostructures. These results allow a great variety of conductive biocompatible cathodes to be used and engineered, opening vast possibilities for the development of bioelectronics and biosensors.

In response to issues raised by modern energy challenges, molecular electrocatalysis is currently attracting a lot of attention to the tailoring of "model" catalysts, notably understanding the mechanisms and kinetic and thermodynamic parameters that occur during a catalytic reaction. In this regard, nature offers extremely efficient enzymes called hydrogenases. These enzymes that catalyze the reversible interconversions between H₂ and H⁺ at high turnover rates are inactivated by O₂. This inactivation yields odd cyclic voltammetric responses originating from a chemical inactivation-redox activation process (IAP). Although IAP has been extensively studied for hydrogenases, their catalytic mechanism is not fully understood because of the intricate but necessary electrical wiring, desorption, and complex biochemical environment required. Here, we report a unique example of IAP based on a nonenzymatic catalyst prepared by mixing rhodium-porphyrinic catalyst and an interconnected multiwalled carbon nanotubes matrix which presents an excellent and stable electron transfer. We combined organic synthesis, electrochemistry, mathematical models, and density functional theory calculations to uncover the molecular IAP at the catalytic metallic site. We present a mechanistic analysis of the noncatalytic and catalytic responses exhibited by this complex, enabling a comprehensive understanding of the thermodynamic and kinetic parameters that govern the IAP. These stepwise studies support a mechanism for glucose oxidation that proceeds most likely through an EC′CE scheme with catalytic steps similar to the ones reported for NiFe hydrogenases. The overall mechanism of the molecular IAP was detailed on the basis of our experimentally validated models and compared to NiFe hydrogenase IAP. Our findings offer novel perspectives to design finely optimized catalysts by eliminating the inactivation phenomena. National Research Foundation (NRF) This project is funded by the National Research Foundation (NRF), Prime Minister’s Office, Singapore, under its Campus for Research Excellence and Technological Enterprise (CREATE) program.

Enzymes are promising electrocatalysts for electron transfer (ET) in many biological processes. Strategies to enhance ET between enzymes and electroactive surfaces include orientation and immobilization of the enzymes and electron mediation. Here, we develop a strategy to couple orientation and electron mediation on electrodes based on carbon nanotubes. This is achieved by the synthesis of a redox mediator that contains an enzyme-orientation site (pyrene), an electron-carrier redox mediator (2,2′-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS)) and an electropolymerizable monomer (pyrrole). The coupling of an enzymatic orientation and a mediated ET in the same chemical structure (pyrrole–ABTS–pyrene (pyrr–ABTS–pyr)) provides a much-improved performance in the bioelectrocatalysis. We demonstrate two fuel cells for the synthesized redox mediator. In a proton-exchange membrane hydrogen/air fuel cell and in a membraneless fuel cell, the pyrr–ABTS–pyr biocathode provides a power density of 1.07 mW cm−2 and 7.9 mW cm−2, respectively. The principle of coupling an enzyme orientation and a redox mediator allows a great variety of mediators to be engineered and provides vast possibilities for the development of fuel cells. Enzymatic fuel cells use enzymes for the redox reactions of fuels, and electron transfer is a key process in generating electricity. Here, the authors develop a redox mediator that is able to both immobilize the enzyme and mediate electron transfer, leading to much-enhanced power densities in fuel cells.

The development of a rapid, affordable, and sensitive diagnostic kit for point-of-care is important in most healthcare settings. In this follow-up paper to our previous work on quantification of dengue NS1 protein via impedimetric measurement, our present technology aims to provide quantification by utilizing proprietary stabilized and improved electroactive immunonanoparticles that bind to the target biomarker and subsequently move along toward the biofunctionalized screen-printed gold electrodes (SPGE) to generate an amperometric signal. The SPGE functions simultaneously as a signal transducer and a solid-state support for a sandwich ELISA-like immunoassay. The successful immunocomplex formation is then recorded electrochemically using a potentiostat, whereby the signal was contributed by the presence of a more hydrophilic redox label than ferrocene, namely radical TEMPO (TEMPO ), on the formulated nanoparticles. In this paper, a bifunctional ligand, thiolated polyethylene glycol (PEG-thiol) polymer, was used to stabilize 20 nm gold colloidal nanoparticles (AuNPs) in the formulation. PEG was incorporated to not only prevent the salt-mediated AuNPs aggregations, but also provide an anchor for antibody and redox species conjugation. To-date, we have successfully miniaturized a 3D-printed prototype device able to sensitively detect and quantify dengue NS1 protein with only 0.6 μL human clinical serum samples diluted in a volume ratio of 1:100 (PBS diluent) in less than 30 min with a simple cyclic voltammetry analysis. The positive and negative samples were also tested with ELISA, a gold standard validation method, which means that the development of the prototype is a promising start as a point-of-care diagnostic technology.

An original versatile methodology for molecular grafting on different surfaces via the photoinduced formation of a covalent bond based on a diazirine group is reported. The synthesis and electrochemical behavior of a new diazirine derivative which acts as a molecular linking bridge bearing both a photoactivatable covalent binding group (diazirine) and a non-covalent binding group (pyrene) is described. The resulting pyrene-diazirine was electropolymerized onto a platinum electrode and under UV irradiation was successfully used to graft ferrocenemethanol and glucose oxidase (model small molecule and protein, respectively), conferring specific properties on the resulting materials. Furthermore, the immobilization of the diazirine derivative onto multi-walled carbon nanotubes (MWCNT) by π-stacking interaction or by electropolymerization onto both bare and MWCNT-coated platinum electrodes enabled photografting of glucose oxidase. Keywords: Diazirine, Pyrene, Photografting, Electropolymerization, Glucose oxidase, Carbon nanotubes

An original strategy for the design of free standing buckypapers using unique molecular catalysts was developed. Pyrene-modified metalloporphyrins enable the formation of stable buckypapers using carbon nanotubes for the oxidation of glucose and reduction of oxygen. The developed molecular buckypapers show high performances and an excellent stability in a glucose fuel cell setup. NRF (Natl Research Foundation, S’pore) Accepted version

International audience; Engineering bioelectronic components and set-ups that mimic natural systems is extremely challenging. Here we report the design of a protein-only redox film inspired by the architecture of bacterial electroactive biofilms. The nanowire scaffold is formed using a chimeric protein that results from the attachment of a prion domain to a rubredoxin (Rd) that acts as an electron carrier. The prion domain self-assembles into stable fibres and provides a suitable arrangement of redox metal centres in Rd to permit electron transport. This results in highly organized films, able to transport electrons over several micrometres through a network of bionanowires. We demonstrate that our bionanowires can be used as electron-transfer mediators to build a bioelectrode for the electrocatalytic oxygen reduction by laccase. This approach opens opportunities for the engineering of protein-only electron mediators (with tunable redox potentials and optimized interactions with enzymes) and applications in the field of protein-only bioelectrodes.

We report the synthesis and electrochemical behavior of an original catalyst bearing a 2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPO) unit and a pyrene group. Anchoring of this bi-functional molecule by π -stacking onto multiwalled carbon nanotubes allows the study of the electrochemical properties of the compound in the immobilized state. These resulting functionalized TEMPO materials were used to detect iron(II) in solution with an experimental detection limit of 3.9 × 10−8 mol L−1 and a linear range between 7.8 × 10−8 and 1.4 × 10−6 mol L−1. Keywords: TEMPO, Multiwalled carbon nanotubes, Pyrene, Iron(II), Electrochemical sensor

Horseradish peroxidase (HRP) was immobilized on redox buckypapers followed by electropolymerization of pyrrole-modified concanavalin A enabling the subsequent additional immobilization of the glycoprotein glucose oxidase (GOx). Biocatalytic buckypapers were formed using pyrene-modified 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) or bis-Pyr-ABTS, a redox mediator, as a cross-linker. ABTS-functionalized buckypaper enhances the electron transfer of the bioelectrocatalytic reduction of H2O2 by HRP. Since H2O2 is produced during glucose oxidation by GOx in the presence of oxygen, the bienzymatic GOx–HRP biocathode achieves the complete reduction of oxygen into water. A clearly improved performance of the biocathode was obtained by using an improved biocompatible immobilization strategy, enabling the prevention of enzyme loss while ensuring both diffusion of glucose and O2 and the local production of H2O2. These freestanding flexible oxygen-reducing biocathodes can operate under physiological conditions and show a high onset potential at 0.60 (±0.01) V. In the presence of glucose (5 mM), such biocathodes exhibit a stable current density output of 1.1 (±0.1) mA cm−2 at 0.1 V under continuous one-hour discharge. Furthermore, a marked increase in lifetime was observed, the biocathode displaying 64% of its initial electrocatalytic activity after 15 days. Accepted version

An original interfacial hybrid cross-linker molecule combined electrochemical and photochemical properties by substitution of two functional groups, pyrene, and diazirine. The first group enables anchoring by strong π-stacking interaction or by electropolymerization onto multi-walled carbon nanotubes (MWCNT). The other photoreactive group allows the covalent link with biomolecules under long-wavelength UV illumination. Diazirine was chosen due to its ability to photogenerate high reactive radicals under UV irradiation. The photoreactivity of these immobilized nanostructured conductive surfaces was tested towards the covalent attachment of tyrosinase which is well known to oxidize a large range of phenolic compounds and its yield and availability was evaluated by amperometric measurements of catechol by using molecular dioxygen. The architecture exhibiting the best analytical characteristics obtained for catechol was then chosen to detect dopamine.

The synthesis and electropolymerization of a pyrrolic concanavalin A derivative (pyrrole-Con A) onto a multiwalled carbon nanotube (MWCNT) deposit is reported. Glucose oxidase was then immobilized onto the MWCNT-poly(pyrrole-Con A) coating by affinity carbohydrate interactions with the polymerized Con A protein. The resulting enzyme electrode was applied to the amperometric detection of glucose exhibiting a high sensitivity of 36 mA cm(-2) mol(-1) L and a maximum current density of 350 μA cm(-2) .

Au(iii) porphyrin was synthesized and evaluated for electrocatalytic oxidation of glucose. These Au(III) porphyrins, immobilized on a multiwalled carbon nanotube matrix, oxidized glucose at low overpotentials. Furthermore, AuNPs were electrogenerated by reduction of the Au(III) porphyrins. The electrocatalytic properties of these compounds towards glucose oxidation were compared and characterized by electrochemistry, electron microscopy and XPS.

It is important to design a functionalization scheme for carbon nanotubes that preserves their outstanding proprieties, while adding new proprieties, thereby enabling their integration in fuel cell applications. In the present work, we describe the production of a non-covalently attached network of porphyrins to multi-walled carbon nanotubes (MWCNT) sidewalls. The approach is based on π–π stacking interactions of pyrene-modified metalloporphyrins onto MWCNT sidewalls. Two configurations of MWCNT–porphyrin hybrid electrodes were both electrochemically characterized and tested under alkaline conditions. Pyrene-functionalized rhodium deuteroporphyrin (Rh(DP)pyr2), was used as an anode in the electrocatalytic oxidation of glucose and pyrene-functionalized tetracarboxyphenyl cobalt porphyrin (Co(TCPP)pyr4) was itself used as a cathode in the electrocatalytic reduction of oxygen. Both electrodes were integrated into a glucose fuel cell system leading to a maximum power output of 0.9(±0.10) mW cm−2. Compared to alternative system approaches, pyrene-modified porphyrin hybrid electrodes and their corresponding fuel cell devices exhibited higher activity, power output, and long term stability.

International audience; The synthesis of five light absorbing triazolobithiophenic thiols, which were utilized for producing self-assembled monolayers (SAMs) on gold surfaces, is presented. The monolayer formation was monitored by cyclic voltammetry, indicating excellent surface coverage. The new triazolobithiophenic compounds exhibited an absorption maximum around 340 nm, which is close to the emission wavelength of a standard nitrogen laser. Consequently these compounds could be used to aid ionization in laser desorption mass spectrometry (MS).

The field of molecular electrocatalysis research includes a wide range of emerging technologies that utilize molecular catalysts to catalyze anodic and/or cathodic reactions within a fuel‐cell setup, and has developed greatly in the last 10 years. Although the vast majority of fuel cells utilize noble metals as catalysts, several systems have been recently developed that are based on molecular catalysts. The focus here is on the integration of molecular catalysts in a fuel‐cell setup, which is contextualized, and which is named as “fuel‐cell‐based molecular‐type catalysts” here. The latter utilize a wide variety of chemical compounds, such as organometallics and organic or bioinspired compounds, to harvest chemical energy to generate current. Here, the state‐of‐the‐art for all molecular catalysts that convert chemical energy in a fuel‐cell setup is discussed and a novel classification system is presented to illustrate how molecular catalysts integrate into the broad field of fuel cells. The current performance of molecular catalysts in systems that use different fuels is summarized, and finally, for the first time, the achievable power outputs of fuel cells using uniquely molecular catalysts are presented. NRF (Natl Research Foundation, S’pore) MOE (Min. of Education, S’pore)

International audience; Electrospun carbon nanofibres (CNFs) containing CNTs were produced by electrospinning and subsequent thermal treatment. This material was evaluated as a bioelectrode for biofuel cell applications after covalent grafting of laccase. Bis-pyrene-modified ABTS was used as a plug to wire laccase to the nanofibres leading to a maximum current density of 100 μA cm−2.

Mesoporous silicon membranes are functionalized with ammonium groups and evaluated as high efficient anion exchange membrane in a miniaturized alkaline glucose fuel cell setup. N-Trimethoxysilylpropyl-N,N,N-trimethylammonium chloride is grafted onto the pore walls of porous silicon resulting in the anionic conductivity enhancement. The functionalization process is followed by FTIR spectroscopy where the optimized parameter could be determined. The ionic conductivity is measured using impedance spectroscopy and gives 5.6 mS cm−1. These modified mesoporous silicon membranes are integrated in a specially designed miniature alkaline (pH 13) glucose/air fuel cell prototype using a conventional platinum-carbon anode and a cobalt phthalocyanine-carbon nanotube cathode. The enhanced anion conductivity of these membranes leads to peak power densities of 7 ± 0.12 mW cm−2 at “air breathing” conditions at room temperature. Keywords: Glucose fuel cell, Porous silicon, Anion exchange membrane, Catalytic inks, Cobalt(II) phthalocyanine, Miniature fuel cell

Simple and highly efficient glucose fuel cells using abiotic catalysts and different ion exchange membranes were designed. The glucose fuel cells are based on a multi-walled carbon nanotube (MWCNT)-supported cobalt phthalocyanine (CoPc) cathode and a carbon black/platinum (C/Pt) anode. The electrocatalytic activity of the MWCNT/CoPc electrode for oxygen reduction was investigated by cyclic and linear sweep voltammetry. The electrochemical experiments show that CoPc exhibits promising catalytic properties for oxygen reduction due to its high overpotential and efficiency at reduced metal load. The MWCNT/CoPc electrodes were applied to the oxygen reduction reaction as air-breathing cathode in a single-chambered glucose fuel cell. This cathode was associated with a C/Pt anode in fuel cell configurations using either an anion (Nafion ® ) or a cation (Tokuyama) exchange membrane. The best fuel cell configuration delivered a maximum power density of 2.3 mW cm −2 and a cell voltage of 0.8 V in 0.5 M KOH solution containing 0.5 M glucose using the Tokuyama membrane at ambient conditions. Beside the highest power density per cathodic catalyst mass (383 W g −1 ), these glucose fuel cells exhibit a high operational stability, delivering 0.3 mW cm −2 after 50 days.

We report an original setup using carbon nanotube matrices as supercapacitors where redox enzymes serve for continuous charging of the capacitors. High currents can be delivered under short pulse discharges. This supercapacitor/biofuel cell hybrid system remains stable for at least 40 000 pulses of 2 mW.

An efficient and easy way of designing free standing redox buckypaper electrodes via the elegant combination of multi-walled carbon nanotubes (MWCNTs) and a bis-pyrene derivative is reported. This bis-pyrene 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid (bis-Pyr-ABTS) acts as a cross-linker between the nanotubes and assures the formation of a mechanically reinforced buckypaper, obtained by a classical filtration technique of a MWCNT suspension in the presence of bis-Pyr-ABTS. In addition, the ABTS derivative assures a mediated electron transfer to laccase. The electroactive buckypapers were characterized in terms of morphology, conductivity, and electrochemical properties. Two setups were evaluated. The first consisted of the immobilization and wiring of laccase enzymes via an inclusion complex formation between the hydrophobic cavity of laccase and the pyrene groups of bis-Pyr-ABTS that are not π-stacked to the nanotubes. The second approach was to evaluate the mediated electron transfer using laccase in solution. For this setup, the developed mediator electrodes demonstrated high performances with maximum currents up to 2 mA ± 70 μA and an excellent operational stability for two weeks with daily one hour discharges using refreshed laccase solutions.

Electrochemical impedance spectroscopy was evaluated for the label free detection of MCF-7 cancer cell in which c-erbB-2 receptor is overexpressed on the cell surfaces. Anti-c-erbB-2, used as a specific antibody, was immobilized on electrogenerated polypyrrole-NHS on electrodes via covalent linking. The polymer formation, the grafting of the antibody, and the recognition event with the cancer cells using MCF-7 as a model cell line, were characterized by using cyclic voltammetry and fluorescence microscopy. The impedimetric sensor showed high sensitivity from 100 to 10 000 cell/mL without needing any labeling step and represents an efficient transduction method for cell selective detection. Keywords: Immunosensors, Anti c-erbB-2, Cell detection, Electrochemical impedance spectroscopy (EIS), Surface modification

We report the functionalization of multi-walled carbon nanotube (MWCNT) electrodes by oxidative electropolymerization of pyrrole monomers bearing pyrene and N-hydroxysuccinimide groups. Both polymers were applied to the immobilization and electrical wiring of Trametes versicolor laccase via chemical grafting or non-covalent binding. A "pseudo" host-guest interaction of polymerized pyrene with a hydrophobic cavity of laccase was used for the oriented enzyme immobilization on MWCNT electrodes. The latter leads to higher catalytic current for oxygen reduction (1.85 mA cm(-2)) and higher electroenzymatic stability (50% after one month).

A photoactivatable poly(pyrrole-diazirine) film was synthesized and electropolymerized as a versatile tool for covalent binding of laccase and glucose oxidase on multiwalled carbon nanotube coatings and Pt, respectively. Irradiation of the functionalized nanotubes allowed photochemical grafting of laccase and its subsequent direct electrical wiring, as illustrated by the electrocatalytic reduction of oxygen. Moreover, covalent binding of glucose oxidase as model enzyme, achieved by UV activation of electropolymerized pyrrole-diazirine, allowed a glucose biosensor to be realized. This original method to graft biomolecules combines electrochemical and photochemical techniques. The simplicity of this new method allows it to be extended easily to other biological systems.

An efficient way of immobilizing and wiring a large amount of laccase on non-covalently-functionalized multi-walled carbon nanotube (MWCNT) electrodes is reported. 1-(2-anthraquinonylaminomethyl)pyrene and 1-[bis(2-anthraquinonyl)aminomethyl]pyrene were synthesized and studied for their capability to non-covalently functionalize MWCNT electrodes and immobilize and orientate laccase on the nanostructured electrodes. This led to high-performance biocathodes for oxygen reduction by direct electron transfer with maximum current densities of (1±0.2) mA cm(-2). The performance of the resulting bioelectrodes could be doubled simply by using the bis-anthraquinone compound. The bioelectrodes show excellent stability over weeks and can thus be envisioned in enzymatic biofuel cells.

We report the design of a novel glucose/O2 biofuel cell (GBFC) integrating carbon nanotube-based 3D bioelectrodes and using naphthoquinone-mediated oxidation of glucose by glucose oxidase and direct oxygen reduction by laccase. The GBFCs exhibit high open circuit voltages of 0.76 V, high current densities of 4.47 mA cm(-2), and maximum power output of 1.54 mW cm(-2), 1.92 mW mL(-1) and 2.67 mW g(-1). The GBFC is able to constantly deliver 0.56 mW h cm(-2) under discharge at 0.5 V, showing among the best in vitro performances for a GBFC. Using a charge pump, the GBFC finally powered a Light Emitting Diode (LED), demonstrating its ability to amplify micro watts to power mW-demanding electronic devices.

This paper details the electrochemical investigation of a deuteroporphyrin dimethylester (DPDE) rhodium(III) ((DPDE)Rh(III)) complex, immobilized within a MWCNT/Nafion electrode, and its integration into a molecular catalysis-based glucose fuel cell. The domains of present (DPDE)Rh(I), (DPDE)Rh-H, (DPDE)Rh(II), and (DPDE)Rh(III) were characterized by surface electrochemistry performed at a broad pH range. The Pourbaix diagrams (plots of E(1/2) vs pH) support the stability of (DPDE)Rh(II) at intermediate pH and the predominance of the two-electron redox system (DPDE)Rh(I)/(DPDE)Rh(III) at both low and high pH. This two-electron system is especially involved in the electrocatalytic oxidation of alcohols and was applied to the glucose oxidation. The catalytic oxidation mechanism exhibits an oxidative deactivation coupled with a reductive reactivation mechanism, which has previously been observed for redox enzymes but not yet for a metal-based molecular catalyst. The MWCNT/(DPDE)Rh(III) electrode was finally integrated in a novel design of an alkaline glucose/O(2) fuel cell with a MWCNT/phthalocyanin cobalt(II) (CoPc) electrode for the oxygen reduction reaction. This nonenzymatic molecular catalysis-based glucose fuel cell exhibits a power density of P(max) = 0.182 mW cm(-2) at 0.22 V and an open circuit voltage (OCV) of 0.64 V.

International audience; This work demonstrates that the desorption/ionization on self-assembled monolayer surface (DIAMS) mass spectrometry, a recent matrix-free laser desorption/ionization (LDI) method based on an organic target plate, is as statistically repeatable and reproducible as matrix assisted laser desorption ionization (MALDI) and thin gold film-assisted laser desorption/ionization (TGFA-LDI) mass spectrometries. On lipophilic DIAMS of target plates with a mixture of glycerides, repeatability/reproducibility has been estimated at 15 and 30% and the relative detection limit has been evaluated at 0.3 and 3 pmol, with and without NaI respectively. Salicylic acid and its d6-isomer analysis confirm the applicability of the DIAMS method in the detection of compounds of low molecular weight.