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The most widely used support in low-temperature fuel cell applications is the commercially available Vulcan XC-72. Herein, we report its functionalization with the home-obtained mesityl copper (Cu-mes) and Cu coordinate (Cu-(dmpz)-L2) organometallic compounds. Pd nanoparticles are anchored on the supports obtaining Pd/CCu‑mes, Pd/CCu(dmpz)L2, and Pd/C (on nonfunctionalized support). The polarization curves of the ethanol oxidation reaction (EOR) show that Pd/CCu‑mes and Pd/CCu(dmpz)L2 promote the reaction at a more negative onset potential, i.e., Eonset = 0.38 V/reversible hydrogen electrode (RHE), compared to 0.41 V/RHE of Pd/C. The mass current density (jm) delivered by Pd/CCu‑mes is considerably higher (1231.3 mA mgPd–1), followed by Pd/CCu(dmpz)L2 (1001.8 mA mgPd–1), and Pd/C (808.3 mA mgPd–1). The enhanced performance of Pd/CCu‑mes and Pd/CCu(dmpz)L2 for the EOR (and tolerance to CO poisoning) is attributed to a shift of their d-band center toward more negative values, compared to Pd/C, because of the formation of PdCu alloyed phases arising from the functionalization. In addition, laboratory-scale tests of the anion exchange membrane-direct ethanol fuel cell assembled with Pd/CCu‑mes show the highest open circuit voltage (OCV = 0.60 V) and cell power density (Pcell = 0.14 mW cm–2). As a result of its high catalytic activity, Pd/CCu‑mes can find application as an anode nanocatalyst in AEM-DEFCs. [ABSTRACT FROM AUTHOR]

The synthesis of catalytic materials containing active sites of various oxidation states (metal, oxide, etc.) for the dual use in reduction and oxidation reactions remains challenging because most of the reported methods for the metallic state are often incompatible with those for the oxide state. A new methodology is reported for the synthesis of a library of bimetallic metal‐oxide materials containing three crystalline phases Ir‐Ru‐IrxRu1‐xO2 by combining the calcination under air and the polymerization of aniline in the presence of IrCl3 and RuCl3 precursors. Morphology, structure, and surface oxidation state studies (XRD, SEM/EDX, S/TEM, XPS) confirm the hypothesis that IrCl3 evolves to Ir while RuCl3 evolves to RuO2 during the calcination under air. An Ir:Ru atomic ratio of 50:50 can be converted into a heterogeneous nanostructure composed of Ir, Ru, and IrxRu1‐xO2 to date, with remarkable catalytic activity for both hydrogen evolution reaction (HER) with a small overpotential of 40 mV and oxygen evolution reaction (OER) with a small overpotential of 290 mV at the metric current density of 10 mA cm−2 in 0.5 m H2SO4. The results can serve as a platform for the development of efficient multifunctional materials for practical use in both catalytic oxidation and reduction reactions. [ABSTRACT FROM AUTHOR]

Glycerol electro‐oxidation reaction was performed in an alkaline environment with an anion exchange membrane fuel cell (AEMFC) operating in bath mode at low Pt‐loadings. BAE‐synthesized Pt/C and PtCe/C nanostructured catalysts were used as anode materials during 4‐hour operation to selectively obtain 65 % and 41 % of glycerate as main product, respectively. The modification of Pt with Ce improved the catalytic activity of the Pt/C catalyst generating 30 % more energy density after 4‐hour operation by achieving a higher degree of glycerol oxidation in cogeneration with added‐value products confirmed by spectroelectrochemical (in situ FTIR) and liquid chromatography coupled with mass spectrometry (LC–MS) analyses. The bifunctional mechanism generated by the presence of Ce is used to explain the improvement in the catalytic activity of Pt/C, due to the properties of this rare earth element to adsorb oxygenated species (OH−) and promote oxidation. The cathode material was a polyol‐synthesized PdFe/C electro‐catalyst for ORR that presented impressive stability and tolerance to glycerol. [ABSTRACT FROM AUTHOR]

Foresee advanced and innovative strategies is a key approach and constitutes a cornerstone for accessing clean, affordable, and reliable energy to satisfy the world's increasing prosperity and economic growth. To this end, hydrogen energy technologies parade as promising sustainable solutions to the looming energy crisis at either the small or large industrial scale, which will enable to reduce significantly our dependence on conventional energy sources based on fossil fuels without increasing atmospheric CO2 levels. Water electrolysis with renewable energy is one of the best solutions to produce hydrogen without COx (CO and CO2) emissions. However, the practical realization of this elegant opportunity of paramount importance is facing several challenges, among which are: (i) the efficient design of cathode and anode catalytic materials exhibiting improved intrinsic and durable activity; (ii) the scale‐up of the system for the large‐scale hydrogen production through the electrochemical water splitting. This review puts these opportunities and challenges into a broad context, discusses the recent research and technological advances, and finally provides several pathways and guidelines that could inspire the development of groundbreaking electrochemical devices for hydrogen production. It also points out the materials design and preparation for the efficient electrochemical production of the molecular hydrogen in acidic and alkaline environments, from a simple electrolytic solution to the water splitting reaction, which is also considered in the process. Furthermore, the main technology keys for designing a reliable electrochemical system will be noticed. [ABSTRACT FROM AUTHOR]

The synthesis of shape and size-controlled free gold nanoparticles (AuNPs) was achieved by wet chemical methods. The UV-vis spectroscopy measurements and trans-mission electron microscopy characterizations confirmed the fine distribution in size and shape of the AuNPs. The zeta potential measurements permitted the evaluation of the stability of the AuNPs suspension. For the first time, the shape dependence on the electrocatalytic activity of these NPs is thoroughly investigated. The underpotential deposition (UPD) of lead reveals that their crystallographic facets are affected by their shape and growth process. Moreover, the glucose oxidation reaction strongly depends on the shape of AuNPs. Indeed, the gold nanocuboids (GNCs) and the spherical gold nanoparticles (GNSs) are significantly more active than the gold nanorods (GNRs) followed by the polyhedrons (GNPs). The oxidation process occurs at low potential for GNCs whereas the current densities are slightly higher for GNSs electrodes. Most importantly, the control of the shape and structure of nanomaterials is of high technological interest because of the strong correlation between these parameters and their optical, electrical and electrocatalytic properties. Keywords Gold nanoparticles. Size. Shape. Lead. UPD. Electrocatalysis. Glucose oxidation, Introduction Gold nanoparticles continue to emerge in many scientific fields because of their unique physicochemical properties such as optical, magnetic, electronic and catalytic properties compared to those of the bulk [...]

We have investigated the promoting effect of Rh addition to Pd‐based materials in the electrooxidation of ethanol and glycerol. Physicochemical characterizations (XRD, EDX, TEM, and XPS) of the PdxRhy/C materials, prepared by bromide anion exchange (BAE), showed that the experimental bimetallic compositions were close to the targeted ones. PdxRhy/C particle sizes ranged from 2.2 to 3.8 nm. The ethanol oxidation reaction (EOR) on the PdxRhy/C catalysts yielded four times larger carbonate (CO32−) amount. As for the glycerol oxidation reaction (GOR), the onset potential on the Pd50Rh50/C catalyst occurred at lower potentials. Chromatographic analysis combined with in situ Fourier transform infrared (FTIR) spectroscopy showed that GOR on the Pd50Rh50/C catalyst selectively and quantitatively produced glycerate and tartronate. The outstanding ability of the Pd50Rh50/C catalyst toward EOR and GOR was correlated to the electronic effect expressed by a negative potential shift (200 mV) and the 47 % alloying degree in the Pd50Rh50/C structure. [ABSTRACT FROM AUTHOR]