Glycerol electrooxidation reaction has been investigated by electrochemical, spectroelectrochemical, and chromatographic methods on palladium–nickel and palladium–silver nanoparticules supported on ...carbon Vulcan XC 72R. These materials, prepared by the so-called “Bromide Anion Exchange” method, exhibited high activity toward the glycerol electrooxidation in alkaline medium showing furthermore an important shift of the onset potential toward low potential values. Electrolysis coupled with high-performance liquid chromatography (HPLC) and in situ Fourier transform infrared spectroscopy (FTIRS) measurements have been used to determine the various compounds generated in the oxidative conversion of this three hydroxyl groups carbon molecule. Some products with high added value such as glycerate and tartronate have been identified. In situ FTIRS results have furthermore shown the pH decrease in the thin layer near the electrode. These results will positively serve as guidelines for future works on the potential use of glycerol in fuel cell devices in a cogeneration of high value chemicals and energy process.
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•Fast preparation of graphene nanosheets by one-pot radiolytic reduction of GO.•One-pot synthesis of graphene nanosheets supported Au-Pt-Pd nanoparticles.•Radiolysis enables to ...engineer highly active Metal/rGO nanocomposites.•Ternary Au50Pt25Pd25/rGO electrocatalyst is 5-fold higher effective than Pt/rGO.•Selective glucose oxidation reaction in a 2-electron process leads to gluconate.
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 Au90Pd10 and trimetallic Au50Pd25Pt25 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.
Palladium has exceptional affinity with hydrogen and the evolution of the surface of its nanomaterials prepared from chemical methods over time is still unclear. Here, the reducing agent effect on Pd ...nanomaterials and their long-term chemical stability were scrutinized by X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD). The subsequent impact on the catalytic properties was examined using the electrochemical oxygen reduction reaction (ORR). We have discovered that the nature of the reducing agent has noteworthy effects on the final composition of Pd nanomaterials prepared from chemical methods. The surface state of the nanomaterials prepared by using sodium borohydride as reducing agent (Pd/C–NaBH
4
) is radically different from those obtained from
l
-ascorbic acid (Pd/C–AA). In addition to pure metal, two oxides were identified: PdO and PdO
x
(
x
> 1). XRD analysis has upheld the presence of PdO only in Pd/C–NaBH
4
, thus underpinning the conclusion that NaBH
4
has drastically changed the Pd structure. Furthermore, the reducing agent substantially affects the electrocatalytic properties. The ORR starts with enhanced kinetics (
E
> 1 V
vs.
RHE) by a 4-electron process, producing
p
(H
2
O
2
) < 0.5% associated with excellent durability over 5000 cycles. Both catalysts outperform all reported data for Pd electrocatalysts. The novelty of this work is combining
ex
/
in situ
XPS and XRD analyses together with ORR as a catalytic model. Overall, this work represents a clear development in our understanding of Pd affinity towards hydrogen and paves new ways for the successful synthesis of Pd-based nanomaterials free from hydrides and oxides, and having impressive catalytic activities.
Electrochemical behavior of carbon-supported platinum and gold-based catalysts towards glucose oxidation and oxygen reduction reaction were investigated separately in alkaline medium before ...implementing the glucose/O
2
fuel cell with the best anode and cathode catalysts. These electrode materials, prepared from a surfactant-free synthesis approach, were then used in low metal loadings in a fuel cell operating in alkaline medium which can be easily removed on resin for analyzing all the reaction products, as any toxic compound has to be avoided for the interest of this specific application. Pt/rGO is the most active anode towards the glucose oxidation. For all tested catalysts, this oxidation reaction leads mainly to gluconate without chromatographically detectable reaction products resulted from C–C bond cleavage.
Graphical Abstract
The oxygen reduction reaction (ORR) is the oldest studied and most challenging of the electrochemical reactions. Due to its sluggish kinetics, ORR became the major contemporary technological hurdle ...for electrochemists, as it hampers the commercialization of fuel cell (FC) technologies. Downsizing the metal particles to nanoscale introduces unexpected fundamental modifications compared to the corresponding bulk state. To address these fundamental issues, various synthetic routes have been developed in order to provide more versatile carbon-supported low platinum catalysts. Consequently, the approach of using nanocatalysts may overcome the drawbacks encountered in massive materials for energy conversion. This review paper aims at summarizing the recent important advances in carbon-supported metal nanoparticles preparation from colloidal methods (microemulsion, polyol, impregnation, Bromide Anion Exchange...) as cathode material in low temperature FCs. Special attention is devoted to the correlation of the structure of the nanoparticles and their catalytic properties. The influence of the synthesis method on the electrochemical properties of the resulting catalysts is also discussed. Emphasis on analyzing data from theoretical models to address the intrinsic and specific electrocatalytic properties, depending on the synthetic method, is incorporated throughout. The synthesis process-nanomaterials structure-catalytic activity relationships highlighted herein, provide ample new rational, convenient and straightforward strategies and guidelines toward more effective nanomaterials design for energy conversion.
The future of analytical devices, namely (bio)sensors, which are currently impacting our everyday life, relies on several metrics such as low cost, high sensitivity, good selectivity, rapid response, ...real-time monitoring, high-throughput, easy-to-make and easy-to-handle properties. Fortunately, they can be readily fulfilled by electrochemical methods. For decades, electrochemical sensors and biofuel cells operating in physiological conditions have concerned biomolecular science where enzymes act as biocatalysts. However, immobilizing them on a conducting substrate is tedious and the resulting bioelectrodes suffer from stability. In this contribution, we provide a comprehensive, authoritative, critical, and readable review of general interest that surveys interdisciplinary research involving materials science and (bio)electrocatalysis. Specifically, it recounts recent developments focused on the introduction of nanostructured metallic and carbon-based materials as robust "abiotic catalysts" or scaffolds in bioelectrochemistry to boost and increase the current and readout signals as well as the lifetime. Compared to biocatalysts, abiotic catalysts are in a better position to efficiently cope with fluctuations of temperature and pH since they possess high intrinsic thermal stability, exceptional chemical resistance and long-term stability, already highlighted in classical electrocatalysis. We also diagnosed their intrinsic bottlenecks and highlighted opportunities of unifying the materials science and bioelectrochemistry fields to design hybrid platforms with improved performance.
The electrochemical activation of glucose was studied at the surface of gold particles prepared either by magnetron sputtering or water-in-oil microemulsion methods. At lower potentials smaller ...sputtered electrocatalysts (
i.e. with Feret’s diameter lower than 5 nm) involved a remarkable activity, which was likely due to their electronic structures. It was suggested that the enhancement of the electrocatalytic performances at the surface of the electrodes composed of largest particles could be related to the formation of “sticking defects” in the nanomaterials.
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•Scrutiny of Bromide Anion Exchange (BAE) straightforward synthesis method.•Molar concentration of metal salt and bromide ion content control BAE method.•Enhanced kinetic of glucose ...electrooxidation on AuPd/C and AuPt/C.•Glycerate and glycolate are the main glycerol reaction products on Pd/C.
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 gold-based 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.
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