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We report the combination of electrospinning and calcination to synthesize many free-standing electrocatalytic electrodes made of nanostructured nickel particles (active sites) and three-dimensional carbon microfibers (support). Precisely, we have used five different nickel precursors to elucidate the nitrogen origin (polyacrylonitrile or metal salts) and the impact on the electrocatalytic properties.

Given the limited access to freshwater compared to seawater, a growing interest surrounds the direct seawater electrolysis to produce hydrogen. However, we currently lack efficient electrocatalysts to selectively perform the oxygen evolution reaction (OER) over the oxidation of the chloride ions that are the main components of seawater. In this contribution, we report an engineering strategy to synthesize heterogeneous electrocatalysts by the simultaneous formation of separate chalcogenides of nickel (NiSx, x = 0, 2/3, 8/9, and 4/3) and cobalt (CoSx, x = 0 and 8/9) onto a carbon-nitrogen-sulfur nanostructured network. Specifically, the oxidative aniline polymerization in the presence of metallic cations was combined with the calcination to regulate the separate formation of various self-supported phases in order to target the multifunctional applicability as both hydrogen evolution reaction (HER) and OER in a simulated alkaline seawater. The OER’s metric current densities of 10 and 100 mA cm−2 were achieved at the bimetallic for only 1.60 and 1.63 VRHE, respectively. This high-performance was maintained in the electrolysis with a starting voltage of 1.6 V and satisfactory stability at 100 mA over 17 h. Our findings validate a high selectivity for OER of ~100%, which outperforms the previously reported data of 87–95%.

The breakthrough in water electrolysis technology for the sustainable production of H2, considered as a future fuel, is currently hampered by the development of tough electrocatalytic materials. We report a new strategy of fabricating conducting polymer-derived nanostructured materials to accelerate the electrocatalytic hydrogen evolution reaction (HER), oxygen evolution reaction (OER), and water splitting. Extended physical (XRD, scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX)) and electrochemical (cyclic voltammetry (CV), linear sweep voltammetry (LSV), electrochemical impedance spectroscopy (EIS)) methods were merged to precisely characterize the as-synthesized iridium and ruthenium modified polyaniline (PANI) materials and interrogate their efficiency. The presence of Ir(+III) cations during polymerization leads to the formation of Ir metal nanoparticles, while Ru(+III) induces the formation of RuO2 oxide nanoparticles by thermal treatment, they are therefore methods for the on-demand production of oxide or metal nanostructured electrocatalysts. The findings from using 0.5 M H2SO4 highlight an ultrafast electrochemical kinetic of the material PANI-Ir for HER (36 &minus, 0 = 36 mV overpotential to reach 10 mA cm&minus, 2 at 21 mV dec&minus, 1), and of PANI-Ru for OER (1.47 &minus, 1.23 = 240 mV overpotential to reach 10 mA cm&minus, 2 at 47 mV dec&minus, 1), resulting in an efficient water splitting exactly at its thermoneutral cell voltage of 1.45 V, and satisfactory durability (96 h).

International audience; The normal operation of an electrochemical converter involving electrocatalytic processes is the simultaneous combination of electrical conductivity (seen as electricity) and catalytic activity involving the same material so-called an “electrode”. Specifically, since the catalytic reactions need an electron transfer between the solid catalyst and the electrolyte either a liquid solution or polymer/ceramic capable of ionic conduction, the electrochemical kinetics depends on the catalyst and the electrolyte, i.e., the interface between them. This means that the nature of the electrocatalyst surface is determining. To reach high thresholds of performance, it is thus highly desired that those electrode materials bridge the two ends of “excellent electronic conductivity” and “outstanding catalytic activity”. In this chapter, we broadly examine how the nature of the utilized metal-based materials of metal, hydroxide, oxide or oxyhydrooxide to design electrodes impacts the energy conversion efficiency.

International audience; The development of high-performance catalytic nanomaterials is important to implement sustainable and electrochemical energy devices of alkaline fuel cells, metal–air batteries, and electrolyzers in the envisaged energy-transition scenarios. Synthesizing effective nanocatalysts as both anode materials for oxidation of glycerol (byproduct of the biodiesel industry) and cathode materials for the oxygen reduction reaction (ORR) is still a bottleneck. Herein, we report palladium-based nanomaterials whose physicochemical and electrochemical properties are tuned by the judicious choice of the support (rGO, Vulcan XC72R), the addition of a coelement (Fe), and the structure (alloy/core–shell). The bimetallic-based electrode shows a drastically enhanced electrocatalytic performance with a beneficial shifting of the onset potential, production of high currents, and good durability for both the ORR (kinetic current density jk = 2 mA cmPd–2 or 1 A mgPd–1) and glycerol oxidation (jp = 2.3 mA cmPd–2 or 1.11 A mgPd–1 at the peak), higher than those of commercial catalysts and existing literature values. The present results also provide new fundamental insights about the accurate measurement of the kinetic metrics of the ORR by employing a rotating-disk (-ring) electrode setup in alkaline electrolytes with metallic catalysts. Indeed, the anodic scanning of the electrode from a low potential to a higher one results in an ultrafast electrochemical kinetics with a positive shift of the half-wave potential of ΔE1/2,anodic/cathodic = 60 mV from the cathodic direction to the anodic one. The kinetic current density dramatically increases, jk,anodic = 19.0×, 6.9×, 3.4×, and 2.4× jk,cathodic at 950, 900, 870, and 850 mVRHE, respectively. The advantage of the synthesis methodology relies on the nonuse of organic molecules as capping agents and surfactants in order to produce bare (ligand-free) bimetallic PdFe electrocatalysts with a clean catalytic surface in a facile and straightforward way.

International audience; Cellulosic biomass, which is basically a polymer of glucose, is the most abundant organic polymer on earth and there is significant interest in the development of advanced materials for its valorization through the waste-toenergy and water-to-chemical scenarios. Hence, a precise investigation of the monomer (glucose) electrooxidation in electrochemical reactors is a key starting point to tackle the whole cellulose and ultimately the entire biomass. To this end, we report herein new insights about the operation of a cogeneration direct alkaline glucose fuel cell (which includes an anion exchange membrane) that simultaneously produces electricity and mainly gluconate as the reaction product. The AuPt nanocatalysts of 3?5 nm particle size finely dispersed onto reduced graphene oxide (rGO) at a 20 wt% metal loading are obtained from an organic surfactant-free method, so-called the bromide anion exchange (BAE). Specifically, the electroanalytical investigation carried out with high-performance liquid ionic chromatography (HPLIC) and liquid chromatography coupled to mass spectrometry (LC-MS) demonstrate no carbon?carbon bond cleavage occurs, which represents an advance towards a CO2-free biomass valorization process. The comparison of the results commonly obtained in a three-electrode half-cell with those in an anion exchange membrane fuel cell shows that the trends in selectivity are the same. The fuel cell operation produces gluconate via a two-electron transfer process at 90% selectivity and 65% Faradaic efficiency. In addition to gluconate, glucuronate is also observed; both compounds are high valueadded chemicals. This work contributes towards the engineering of novel electrocatalytic interfaces for the valorization of the surplus biomass into energy and chemicals.

International audience; The development of non-noble metal electrocatalysts for energy conversion and storage devices such as fuel cells and electrolyzers has gained renewed interest in the last decades. Specifically, transition metal oxides are one of the material categories that showed remarkable efficiency and stability for hydrogen electrode reactions. This chapter summarizes the recent advances in the design and development of transition metal oxides for hydrogen evolution and oxidation reactions in different electrolytes. Special attention was given to the origin of the electrocatalytic performance and stability while relying on the elaboration-structure-efficiency correlation. Additionally, the mechanism of hydrogen electrode reactions in alkaline and acid media is discussed.

International audience; The design of efficient electrochemical setups to precisely and timely quantify the oxygen permeability, which dictates how the lens let O2 to reach the eye, is important for the development lens-based materials. We report herein a home-made electro-analytical platform made of a 3D-printed diffusion electrochemical cell to assess this parameter. The design overcomes edge effects and allows analysis under conditions similar to lens wear where the liquid is in contact to the inner surface while the gaseous O2 is in contact with the outer surface. The testing of three types of contact lens materials (flexible polymer, rigid polymer, and gel-type) showed that the O2 permeability can be fairly well evaluated by the chronoamperometry study of oxygen reduction reaction. Under conditions similar to those of lens wear, our findings showed that the measurement error was 6 %, which offer an alternative to the classic gas-to-gas method for O2 permeability determination.

International audience; Tartaric acid emerges as an ecofriendly organic for the biogenic preparation of micro-and nanostructured materials. For those synthesis mainly dictated by the coordination chemistry, questions remain open about the impact of the alkalinity on the nature of the resulting material as well as the properties. On the other hand, the design of advanced catalytic materials for the direct production of hydrogen peroxide from the air is particularly needed. We report herein new synthesis, physicochemical and electrocatalytic insights from bismuth-based materials. It was found that the tight control of the alkalinity of the synthesis medium through the molar ratio R = [sodium hydroxide]/[bismuth (III) nitrate] leads to the production of a library of bismuth-based materials composed of metallic, (oxy)hydroxide, and oxide structures owing to the bismuth-tartrate complexes as intermediates. Electroanalytical studies show an oxygen-to-hydrogen peroxide selectivity in 0.1 M KOH of 77, 88 and 92% for R = 0, 12 and 30, respectively. In 1 M KOH, the selectivity is 90 and 96% for R = 12 and 30, respectively. The production rate is 69 ± 3 and 44 ± 3 mol kg −1 cm −2 during 2 h, corresponding to a faradaic efficiency of 92 ± 4 and 62 ± 5% for R = 12 and 30, respectively. Those results place the present materials among the best known oxygento-hydrogen peroxide reduction catalysts without the need for preparing alloys or specific surface modification. This work contributes in engineering novel catalytic materials for the advanced application of the on-site production of valuable chemicals.

International audience; Electrochemical energy converters based on biomass-based organic molecules such as glucose have recently demonstrated great potential for the development of functional bioimplantable devices such as pacemakers, but such converters lack efficient metal-based anode nanocatalysts, which could combine the stability of parameters with high performance. Here, we elaborate a technique of femtosecond laser ablation in water to synthesize bare (ligand-free) PdAu alloy nanoparticles with constituents having a variable ratio and explore these nanoparticles as electrocatalysts for glucose oxidation. Our data evidence that the combination of two metals in one bare nanoformulation can result in a strong synergetic effect, which makes the combination of high catalytic activity toward glucose oxidation with ultrafast kinetics at low potentials possible due to the presence of Au and Pd, respectively, while a bare uncontaminated surface ensures outstanding catalytic performance. We show that at an optimal ratio of constituents (50%/ 50%), PdAu nanoparticles can provide a mass activity of 60 A g −1 and an onset potential lower than 0.27 V vs. RHE, which outperform all currently existing nanoparticle-based electrodes. Our results show that bare nanomaterials prepared by laser-ablation synthesis can offer much improved characteristics as electrocatalysts for energy conversion and storage applications, while the versatility of laser synthesis can be extended to other alloy architectures in order to provide optimal characteristics for a concrete catalytic process.

Three-dimensional (3D) gas-diffusion electrodes (GDEs) as support for catalytic nanoparticles are important to the electrolysis and fuel cell fields to facilitate reactant transport and distribution and reach higher current densities. Hence, the assembly of nanostructured catalytic particles directly onto GDEs during the synthesis could be a powerful one-step strategy to target high performance and long-term durability thanks to the induced strong nanoparticle–support interaction. We report herein the use of bromide anions to shape the anisotropic growth of nanostructured desert-rose-like gold particles directly onto the GDE, as a freestanding GDE–Au catalyst for straightforward use in electrolysis without an additional step. We showed that the bromide ions determine the anisotropy of the particles, resulting in the growth of gold into nanoplates enclosed by (111) facets. The formation of hierarchical nanostructured three-dimensional (3D) Au at the GDE surface was explained by the nanoparticle-mediated aggregation mechanism and the preferential adsorption of Br– on the (111) facet, leaving behind dominant planar structured nuclei, which then self-assemble. Electrocatalytic tests toward the glycerol electro-oxidation demonstrated that the as-synthesized freestanding surfactant- and binder-free GDE–Au material (100 μgAu cm–2) delivered a high specific peak current density of jp = 33 mA cmAu–2, which is three and seven times higher than the tested commercial Au/C nanocatalyst at loadings of 76 and 152 μgAu cm–2, respectively. This study provides future directions for the synthesis and application of nanostructured catalysts for alcohol oxidation as an alternative to anodic oxygen evolution, which consumes the majority of the electricity input during the electrolysis.

International audience; The water splitting aims to produce H2 for fuel cells and a number of industrial processes such as the ammonia synthesis and the metals refining. There is actually a major limitation about the development of cost-effective and efficient electrocatalysts to lower the cell voltage that must be overcome to perform sequentially the overall reaction that is 2H2O → 2H2 + O2. In the present study, we combined Ni and Co as the promising alternative catalytic metals to Pt-group metals as well as N and S as the doping elements to fabricate self-supported electrocatalysts for hydrogen evolution (HER) and oxygen evolution (OER) in alkaline media. To these ends, the polymerization of the aniline into polyaniline (PANI) in the presence of Ni(II) and Co(II) followed by calcination in air resulted in the formation of heterogeneous catalytic materials self-supported onto a matrix made of C, N, S, Ni and Co. Enhanced activity and durability were recorded for the hybrid and bimetallic PANI-NiCo composite.

There is currently great interest for the development of electrochemical reactors to be implemented for the emerging world-class reactions of hydrogen evolution (HER), CO2 reduction (CO2RR) and N2 reduction (N2RR) in order to electro-synthesize high value-added chemicals. However, precisely how this could be achieved in a cheap and sustainable way remains a puzzle for scientists since the electrochemical kinetics of the oxygen evolution reaction (OER) is the major limitation. Increasing interest surrounds the development of low energy consumption electrolyzers capable of oxidizing selectively biomass-based organics instead of water for a dual production of chemicals (paired electrosynthesis). Also, the state-of-the-art electrocatalyst is in the form of nanoparticles either dispersed on carbon supports or in liquids in the presence of stabilizers to prevent the nanoparticles' aggregation, detachment and performance loss. In this report, free-standing surfactant- and binder-free silver–gold nanoporous and nanoalloyed catalysts are successfully synthesized via a simple and effective approach directly on a gas diffusion electrode (GDE@AgAu). Physicochemical and electrocatalytic analyses show that the obtained activity and selectivity of metallic nanocatalysts towards the glycerol electrooxidation reaction in alkaline media depend on their morphology and composition. Specifically, an onset potential of Eonset = 0.3 V vs. RHE and a record peak current density of jpeak = 18 A mgAu−1 (290 mA cm−2) at GDE@AgAu in comparison with those of the tested commercial Au/C catalyst (Eonset = 0.7 V vs. RHE and jpeak = 2.8 A mgAu−1 or 44 mA cm−2) were obtained. Also, an unprecedented selectivity in glycerol electrooxidation towards two products of high interest, formate (66%) and glycolate (32%), has been obtained. GDE@AgAu is thus a potential substitute as an anode material for commercial Au and Pt-based catalysts for efficient alcohol electroreforming with low energy consumption and cogeneration of H2, CO2 or N2 electrolyzers. The present method that combines direct growth, galvanic replacement and nanostructuration provides a smart route for creating new designs for catalyst nanofabrication in order to target high electrocatalytic performance.

Polyaniline (PANI) is a candidate for electrocatalysis, and can be combined with metal nanoparticles to fabricate high-performance electrodes for electrochemical energy conversion and storage. However, its intrinsic properties appear to be dependent on the synthesis conditions so that from the majority of the reports, it is quite difficult to establish an overall performance trend. In this contribution, we report an extensive and systematic physicochemical and electrochemical screening of the potentiality of chemically synthesized PANI as an electrode material to provide an overall understanding of the effect of the entire synthesis conditions. We have integrated different methods (TGA-DSC, XRD, SEM, EDX, FTIR, BET, CHNS, XPS, CV, and EIS) to deeply examine the as-synthesized materials and interrogate their electrocatalytic efficiency towards hydrogen evolution reaction, which was chosen as a model reaction of critical importance for H2 production from water splitting. It was found that all the synthesis parameters affect strongly the physical and electrochemical characteristics of the PANI-based materials. Specifically, XPS analysis contributed to identify the oxidation levels of the PANI samples on the basis of oxidizing agents. The outcomes provided by the study delineate a rational pathway for the further design and fabrication of PANI-based metal nanoparticles as advanced electrode materials.

Ubiquitous electrochemistry is expected to play a major role for reliable energy supply as well as for production of sustainable fuels and chemicals. The fundamental understanding of organics-based electrocatalysis in alkaline media at the solid-liquid interface involves complex mechanisms and performance descriptors (from the electrolyte and reaction intermediates), which undermine the roads towards advance and breakthroughs. Here, we review and diagnose recently designed strategies for the electrochemical conversion of organics into electricity and/or higher-value chemicals. To tune the mysterious workings of nanocatalysts in electrochemical devices, we examine the guiding principles by which the performance of a particular electrode material is governed, thus highlighting various tactics for the development of synthesis methods for nanomaterials with specific properties. We end by examining the production of chemicals by using electrochemical methods, from selective oxidation to reduction reactions. The intricate relationship between electrode and selectivity encourages both of the communities of electrocatalysis and organic synthesis to move forward together toward the renaissance of electrosynthesis methods.

Glucose is an environmentally friendly and sustainable carbohydrate that is actually a cyclized aldehyde in aqueous solution i.e. a hemiacetal. Its selective oxidation by the anomeric carbon in C1-position without any function protection is of great interest for cogeneration because the electrochemical process enables converting this highly functionalized organic molecule into electricity, heat and added-value chemicals. For this objective, we decided to synthesize effective nanomaterials towards glucose conversion at the anode and the oxygen reduction reaction (ORR) in the cathodic side of a fuel cell. The physical characterizations of the prepared materials and their electrochemical analysis at each half-cell, permitted to optimize the activity of the electrodes according to their elemental composition and structure. Furthermore, a constructed direct glucose fuel cell (DGFC) delivered an open-circuit voltage of 1.1 V in 0.5 mol L‒1 NaOH and an outstanding output power of 2 mW cm‒2 in 0.5 M KOH (Figure 1a). Complementary analytical techniques were employed to quantify the reaction processes involved in each compartment, to determine the reaction products resulted from the glucose transformation and thereby, to understand reaction mechanisms of the glucose oxidation and the ORR over the synthesized electrode materials used in alkaline medium. As results, the identification of gluconate as the sole reaction product in the anodic side showed a selective 2-electron conversion of glucose (Figure 1b), while the ORR proceeded through a 4-electron pathway over the designed cathode catalyst (Figure 1c). Figure 1: (a) Fuel cell polarization curves for different concentrations of glucose in a single fuel cell. Anode: 20 wt.% Au/C (0.18 mgAu cm‒2); cathode 20 wt.% Pt/C (0.17 mgPt cm‒2); Fumatech AEM. Anode: 0.5 mol L‒1 KOH + glucose (deoxygenated by N2); cathode: 0.5 mol L‒1 KOH + O2. (b) LC–MS negative ionization mass spectrum (M-1) of the product. (c) Electrochemical durability tests: Comparison of the ORR polarization curves (at 5 mV s−1) before (black) and after 1000 CVs (red); insets show the normalized specific electrochemical active surface area (SECSA) decay over the 1000 cycles from 0.05 to 1.1 V vs. RHE at 50 mV s−1. Acknowledgments The authors gratefully acknowledge financial support from the French National Research Agency ANR-ChemBio-Energy References 1. Y. Holade et al., ChemSusChem, 9, 252 (2016). Figure 1

International audience; The future of fuel cells that convert the chemical energy to electricity relies mostly on the efficiency of oxygen reduction reaction (ORR) due to its sluggish kinetics. By 2effectively bypassing the use of organic surfactants, post-synthesis steps for the immobilization onto electrodes, the catalytic inks preparation using binders, and the common problem ofnanoparticles detachment from supports involved in traditional methodologies, we demonstrate a versatile electrodeposition method for growing anisotropic microstructures directly onto a threedimensional (3D) carbon felt electrode, using platinum nanoparticles as elementary building blocks. The as-synthesized materials were extensively characterized by integrating methods of physical (TGA, XRD, SEM, ICP, XPS) and electroanalytical (voltammetry, EIS) chemistry to examine the intricate relationship of material-to-performance and select the best-performing electrocatalyst to be applied in the model reaction of ORR for its practical integration into a microbial fuel cell (MFC). A tightly optimized procedure enables decorating an electrochemically activated carbon felt electrode by 40-60 nm ultrathin 3D-interconnected platinum nanoarrays leading to a hierarchical framework of ca. 500 nm. Half-cell reactions reveal that the highly rough metallic surface exhibits improved activity and stability towards ORR (Eonset ~1.1 V vs. RHE, p(HO2‒) < 0.1%) and hydrogen evolution reaction (HER, -10 mA cm−2 for only 75 mV overpotential). Owing to its unique features, the developed material showed distinguished performance as an air-breathing cathode in a garden compost MCF exhibiting better current and faster power generation than its equivalent classical double chamber. The enhanced performance of the material obtained herein is explained by the absence of any organic surfactant on the surface of the nanoarrays, the good metal-support interaction, the particular morphology of the nanoarrays, and the reduced aggregation/detachment of particles. It promises a radical improvement in current surface reactions and paves a new way towards electrodes with regulated surface roughness allowing for their successful application in heterogeneous catalysis

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The practical implementation of air-breathing microbial fuel cell (MFC) is critically linked to the development of efficient materials as cathode and electrochemically active biofilm-based anode. In this contribution, we demonstrate the feasibility by decorating a 3D carbon felt electrode with Pt nanoarrays (CF@Pt) as a bifunctional electrode material as efficient garden compost bioanode and air-breathing cathode. Half-cell electrochemical characterizations reveal that the onset potential of the anode reaction negatively shifts of about 800 mV to reach −0.4 V vs Ag/AgCl after the growth of the biofilm onto CF@Pt. The investigation before and after the biofilm formation shows that Pt nanoarrays act as excellent electron relays, reducing significantly the charge transfer resistance. For MFC application (with a proton exchange membrane), the use of CF@Pt as bioanode’ scaffold and CF@Pt air-cathode enables a drastically enhanced power density of Pmax = 292.3 mW m−2, and a high short-circuit current density jsc = 1.9 A m−2.

We report a novel “one-pot”, convenient and efficient method based on radiolysis to synthesize gold-based nanoparticles finely dispersed on reduced graphene oxide (rGO) nanosheets obtained from reductive transformation of graphene oxide (GO). Extensive characterizations of the metal/rGO nanocomposites were performed and revealed that the optimized bimetallic Au 90 Pd 10 and trimetallic Au 50 Pd 25 Pt 25 materials were mostly nano-alloyed. Not only the multimetallic catalysts demonstrate high electrocatalytic performances towards glucose in alkaline medium, but they also surpass the majority of the reported noble metals based nanocatalysts. The spectroelectrochemical investigations have highlighted a 2-electron reaction process leading to gluconate, a high added-value chemical used in various industries. Definitely, the strategies developed herein pave new rational pathways for the design of effective anode catalysts for glucose-based electrochemical energy converters and the scalability in the catalyst composition opens up new avenues in the efficient application of graphene-based nanocomposites as promising electrode materials in the electrocatalysis of carbohydrates.

The selective electrochemical conversion of highly functionalized organic molecules into electricity, heat, and added-value chemicals for fine chemistry requires the development of highly selective, durable, and low-cost catalysts. Here, we propose an approach to make catalysts that can convert carbohydrates into chemicals selectively and produce electrical power and recoverable heat. A 100% Faradaic yield was achieved for the selective oxidation of the anomeric carbon of glucose and its related carbohydrates (C1-position) without any function protection. Furthermore, the direct glucose fuel cell (DGFC) enables an open-circuit voltage of 1.1 V in 0.5 m NaOH to be reached, a record. The optimized DGFC delivers an outstanding output power Pmax =2 mW cm(-2) with the selective conversion of 0.3 m glucose, which is of great interest for cogeneration. The purified reaction product will serve as a raw material in various industries, which thereby reduces the cost of the whole sustainable process.

Direct growth of hierarchical micro/nanostructured metal arrays on a 3D substrate is a powerful tool to enhance the catalytic efficiency of metal particles towards a wide range of substrates. In this contribution, we demonstrate a novel and versatile method for growing anisotropic microstructures directly onto a 3D carbon paper electrode, using Au, Pd and Pt nanoparticles as elementary building blocks. It was determined that halides play a crucial role in the morphology of synthesized Au particles, leading to either complex flower-like rough surfaces (exhibiting high catalytic activity) or featureless smooth surfaces (exhibiting low catalytic activity). Of the three metal materials studied, the Pt decorated carbon paper (Pt@carbon) material exhibits a high electrocatalytic activity toward the oxygen reduction reaction in an alkaline medium. We demonstrate that this new Pt material can operate as a cathode in an alkaline glucose fuel cell exhibiting outstanding peak power density of 2–3 mW cm−2 (using an anode of Au@carbon or Pt@carbon at room temperature and low metal loading without any fuel circulation). This newly described fabrication approach allows for the rational control of metallic particle growth, paving a new way towards materials with regulated surface roughness allowing for tuneable physical, optical and catalytic properties.

A comprehensive approach is used in this chapter to explain the electrochemical system from two to three electrodes that require a reference electrode. Methods for cleaning glass electrochemical cells are described. Cyclic voltammetry used as an electrochemical basic characterization method is presented. Oxygen reduction is presented as an example of a reaction, and the main steps to assess the kinetics parameters are explained in detail. The electrochemical impedance spectroscopy is presented as a complementary tool to characterize the electrodes’ materials and the reactions.

International audience; The design and fabrication of durable nanocatalysts to efficiently and selectively electro-oxidize organic molecules toward value-added product(s) is an important starting point for the future deployment of electrochemical "cogeneration" devices with the triple advantage of producing electricity, heat and fuels/chemicals. This interdisciplinary research requires a synergistic effort from three communities of electrochemistry/electrocatalysis, material science and organic chemistry. To this end, we chose to explore the integration of different electrochemical and analytical techniques to study the outstanding ability of gold-based nanomaterials in the electrocatalytic oxidation of mono- and di-saccharides. In order to rationalize the previous outcomes on the selective catalysts for glucose-to-gluconate conversion toward cogenerating organic electrosynthesis (ECS Trans., 77, 1547 (2017)), a multivariate study is carried out in alkaline and neutral pHs by examining three substrates, glucose, galactose, lactose and different electrodes. Electroanalytical investigation revealed that these substrates are selectively oxidized at their Cl-position (two transferred electrons). At pH 7.4, the corresponding lactone and acid forms were detected by their specific vibration bands of 1744 and 1780 cm(-1), which is explained by a local pH decrease within the thin-electrolyte. Our study delineates a broad strategy for organic electrosynthesis in electrochemical cells by controlling electrode materials fabrication. (C) The Author(s) 2018. Published by ECS.

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International audience; In this work, different experimental parameters influencing the straightforward nanoparticles synthesis method, so-called Bromide Anion Exchange (BAE) were scrutinized. It was found that a bromide ion to metal(s) molar ratio of 1.5 gave the best electrochemical activity of the obtained catalysts toward the organics oxidation. The revisited BAE synthesis approach allows the preparation of highly active AuPt/C and AuPd/C nanomaterials. It has been highlighted that this method changes drastically the structure of AuPd nanostructures leading to alloyed system when Au atomic content is higher than 50%. These goldbased materials can be considered as advanced surfactant-free nanoparticles for anode electrodes design in abiotic or hybrid glucose biofuel cell. Furthermore, qualitative and quantitative analyses of glycerol conversion indicate that glycolate and glycerate are the main final products with selectivity higher than 40 and 30%, respectively