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Selective electrochemical conversion of CO2 to HCOOH is obtained at the surface of a carbon-supported bimetallic cathode material composed of copper and palladium nanoparticles. Polycrystalline copper or large copper particles are well-known to catalyze CO2 reduction to hydrocarbons at relatively negative potentials, or when their surface is covered by copper oxides (Cu2O and CuO). Cu-based materials modified by various palladium contents (0< × <100), were synthesized by using the microwave-assisted polyol method to serve as a cathode in the selective CO2-into-HCOOH transformation. Herein, we developed a targeted preparation route toward the metal content/catalytic activity relationship correlating atomic ratio with faradaic efficiency (FE) to formate formation (ca. 60% FE) at - 0.72 V vs. RHE, which represents a 703 mV overpotential at pH=7. Consequently, the occurrence of this reduction reaction slows down the parallel H2 production from the solvent consumption, while the neighboring Cu- Pd provides excellent activity and a good efficiency toward CO2 reduction via the hydridation of the CO2 molecule to orientate the reaction to formate rather than carbon monoxide or H2 evolution. [ABSTRACT FROM AUTHOR]

The ethylene glycol oxidation reaction on nickel and ruthenium modified palladium nanocatalysts was investigated with electrochemical, spectroelectrochemical, and chromatographic methods. These carbon‐supported materials, prepared by a revisited polyol approach, exhibited high activity towards the ethylene glycol electrooxidation in alkaline medium. Electrolysis coupled with high performance liquid chromatography/mass spectrometry (HPLC‐MS) and in situ Fourier transform infrared spectroscopy (FTIRS) measurements allowed us to determine the different compounds electrogenerated in the oxidative conversion of this two‐carbon molecule. High value‐added products such as oxalate, glyoxylate, and glycolate were identified in all electrolytic solutions, whereas glyoxylate was selectively formed at the Ru45@Pd55/C electrode surface. In situ FTIRS results also showed a decrease in the pH value in the thin layer near the electrode as a consequence of OH− consumption during the spectroelectrochemical experiments. [ABSTRACT FROM AUTHOR]

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/O2 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. [ABSTRACT FROM AUTHOR]

The efficient design of highly active and durable materials towards the ultimate goal of improving kinetics of the oxygen reduction reaction (ORR), which allow enhanced performance in solid alkaline membrane fuel cells (SAMFCs), remains elusive. Seminal studies have shown that by alloying a noble metal such as palladium to a transition metal, it is possible to tune the electronic and/or bifunctional properties enabling substantial ORR performance to be achieved, thereby designing a costly catalyst. Herein, we address and discuss new findings from deeper ORR investigations at palladium-based nanostructures in an alkaline medium. We exploited and manipulated the straightforward and fast synthesis method, the so-called “Bromide Anion Exchange”, to prepare surfactant-free PdM/C (M = Fe, Mn) nanocatalysts exhibiting unprecedented activity and stability towards ORR. PdFe/C from bromide anion exchange (BAE) enables 40- and 4-fold enhancement in terms of exchange current density and kinetic current density and ca. 100 mV gains compared to the polyol microwave-assisted method. After 20 000 cycles of accelerated potential cycling test (APCT), our findings indicate that the present PdM/C bimetallics outperform, to the best of our knowledge, most of the data reported for ORR in alkaline media for Pd-based transition metals. The improved catalytic performances are assigned to the absence of any organic contaminants or protective ligands on their surface and their relatively heterogeneous character comprising nanoalloys and nanowire oxides. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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Cover Feature: Insight into the Electrooxidation Mechanism of Ethylene Glycol on Palladium-Based Nanocatalysts: In Situ FTIRS and LC-MS Analysis (ChemElectroChem 21/2020) Keywords: ethylene glycol; electrooxidation; energy conversion; fuel cells; heterogeneous catalysis EN ethylene glycol electrooxidation energy conversion fuel cells heterogeneous catalysis 4285 4285 1 11/16/20 20201102 NES 201102 B The Cover Feature b illustrates the mechanism of ethylene glycol electrooxidation at the surface of Pd-based catalysts. Ethylene glycol, electrooxidation, energy conversion, fuel cells, heterogeneous catalysis. [Extracted from the article]