The recent developments in biomass-derivative fuelled electrochemical converters for electricity or hydrogen production together with chemical electrosynthesis have been reviewed.

Partial galvanic replacement of silver atoms by those of gold was optimized to fabricate free-standing highly active and selective electrocatalysts for glycerol electrooxidation.

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Glycerol is a cheap, non‐toxic, and renewable by‐product of the rapid expansion of biodiesel and soap producers around the world. Glycerol electroforming is a method of oxidizing glycerol into valuable chemicals of interest to the pharmaceutical, cosmetics, polymer, and food industries. One of the technologies that have been studied over the past decades is to couple glycerol oxidation with the production of pure hydrogen in an electrolysis cell (so‐called electrolyzer), which has shown the advantage of consuming a much lower theoretical amount of electricity than conventional water electrolysis. The efficiency of this device is influenced by the nature, structure, and composition of the electrode material. This mini‐review concerns the understanding of glycerol electro‐oxidation, a brief state of the art of nanomaterials currently used to prepare electrode materials, and some results concerning the performance of electrolyzers in alkaline conditions that combine the efficient production of value‐added chemicals and hydrogen.

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 j k = 2 mA cm Pd −2 or 1 A mg Pd −1) and glycerol oxidation (j p = 2.3 mA cm Pd −2 or 1.11 A mg Pd −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 ΔE 1/2,anodic/cathodic = 60 mV from the cathodic direction to the anodic one. The kinetic current density dramatically increases, j k,anodic = 19.0×, 6.9×, 3.4×, and 2.4× j k,cathodic at 950, 900, 870, and 850 mV RHE , 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.

Three-dimensional (3D) gas diffusion electrodes (GDEs) as support for catalytic nanoparticles are important to the electrolysis and fuel cells 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 nanoparticlesupport 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 a growth of gold into nanoplates enclosed by (111) facets. The formation of hierarchical nanostructured 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 towards the glycerol electrooxidation demonstrated that the as-synthesized freestanding surfactant-and binder-free GDE-Au material 2 (100 µgAu cm −2) delivered a high specific peak current density of jp = 33 mA cmAu −2 , which is 3 and 7 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.

The electrocatalytic oxidation of glycerol by metal electrocatalysts is an effective method of low-energy-input hydrogen production in membrane reactors in alkaline conditions. The aim of the present study is to examine the proof of concept for the gamma-radiolysis-assisted direct growth of monometallic gold and bimetallic gold–silver nanostructured particles. We revised the gamma radiolysis procedure to generate free-standing Au and Au-Ag nano- and micro-structured particles onto a gas diffusion electrode by the immersion of the substrate in the reaction mixture. The metal particles were synthesized by radiolysis on a flat carbon paper in the presence of capping agents. We have integrated different methods (SEM, EDX, XPS, XRD, ICP-OES, CV, and EIS) to examine in detail the as-synthesized materials and interrogate their electrocatalytic efficiency for glycerol oxidation under baseline conditions to establish a structure–performance relationship. The developed strategy can be easily extended to the synthesis by radiolysis of other types of ready-to-use metal electrocatalysts as advanced electrode materials for heterogeneous catalysis.

Abstract.A series of Group 13 complexes MLX 2 (M = Al or Ga, L = SC 6 H 4 -2-P t Bu 2 or OC 6 H 4 -2-P t Bu 2 , X = Me or C 6 F 5 ) have been synthesized and characterized by multinuclear NMR spectroscopy and single crystal X-ray diffraction. Reactions of Me 3 Al or Me 3 Ga with an equivalent of either 2-t Bu 2 P(C 6 H 4 )OH (1) or 2-t Bu 2 P(C 6 H 4 )SH (5) resulted in the formation of four new (2,3,6, and 7), 4-coordinate dimethyl chelate (S,P or O,P) complexes via methane elimination. The dimethyl gallium complexes (3 and 7) underwent a further reaction with excess B(C 6 F 5 ) 3 , and through ligand exchange (methyl/pentafluorophenyl), resulted in the disubstituted bis(pentafluorophenyl) analogs (4 and 8). Cyclic voltammetry (CV) experiments for all compounds in the presence of and the absence of (1-8) CO 2 were performed. For compounds showing cathodic reduction waves under CO 2 (2,3,4, and 6), bulk electrolysis experiments were performed. Electrochemical studies indicate that, for several compounds, a transient CO 2 adduct is formed which undergoes a one-electron, irreversible (or partially irreversible) reduction to form an unstable radical anion.