The recent advances in electrocatalysis for oxygen reduction reaction (ORR) for proton exchange membrane fuel cells (PEMFCs) are thoroughly reviewed. This comprehensive Review focuses on the low- and non-platinum electrocatalysts including advanced platinum alloys, core–shell structures, palladium-based catalysts, metal oxides and chalcogenides, carbon-based non-noble metal catalysts, and metal-free catalysts. The recent development of ORR electrocatalysts with novel structures and compositions is highlighted. The understandings of the correlation between the activity and the shape, size, composition, and synthesis method are summarized. For the carbon-based materials, their performance and stability in fuel cells and comparisons with those of platinum are documented. The research directions as well as perspectives on the further development of more active and less expensive electrocatalysts are provided.

http://repository.ust.hk/ir/bitstream/1783.1-77094/1/acs.chemrev.5b00462_withlink.pdf

Recent Advances in Electrocatalysts for Oxygen Reduction Reaction

A review on g-C3N4-based photocatalysts

This Account reports the synthesis and characterization of dendrimer-encapsulated metal nanoparticles and their applications to catalysis. These materials are prepared by sequestering metal ions within dendrimers followed by chemical reduction to yield the corresponding zerovalent metal nanoparticle. The size of such particles depends on the number of metal ions initially loaded into the dendrimer. Intradendrimer hydrogenation and carbon−carbon coupling reactions in water, organic solvents, biphasic fluorous/organic solvents, and supercritical CO2 are also described.

http://rcrooks.cm.utexas.edu/research/resources/Publications/rmc113.pdf

Dendrimer-Encapsulated Metal Nanoparticles: Synthesis, Characterization, and Applications to Catalysis

Ligand design is becoming an increasingly important part of the synthetic activity in chemistry. This is of course because of the subtle control that ligands exert on the metal center to which they are coordinated. Ligands which contain significantly different chemical functionalities, such as hard and soft donors, are often called hybrid ligands and find increasing use in molecular chemistry. Although the interplay between electronic and steric properties has long been recognized as essential in determining the chemical or physical properties of a complex, predictions remain very difficult, not only because of the considerable diversity encountered within the Periodic Table-different metal centers will behave differently towards the same ligand and different ligands can completely modify the chemistry of a given metal-but also because of the small energy differences involved. New systems may-even through serendipity-allow the emergence of useful concepts that can gain general acceptance and help design molecular structures orientated towards a given property. The concept of ligand hemilability, which finds numerous illustrations with hybrid ligands, has gained increased acceptance and been found to be very useful in explaining the properties of metal complexes and in designing new systems for molecular activation, homogeneous catalysis, functional materials, or small-molecule sensing. In the field of homogeneous enantioselective catalysis, in which steric and/or electronic control of a metal-mediated process must occur in such a way that one stereoisomer is preferentially formed, ligands containing one or more chiral oxazoline units have been found to be very valuable for a wide range of metal-catalyzed reactions. The incorporation of oxazoline moieties in multifunctional ligands of increasing complexity makes such ligands good candidates to display hemilabile properties, which until recently, had not been documented in oxazoline chemistry. Herein, we briefly recall the definition and scope of hemilabile ligands, present the main classes of ligands containing one or more oxazoline moieties, with an emphasis on hybrid ligands, and finally explain why the combination of these two facets of ligand design appears particularly promising.

Hemilability of Hybrid Ligands and the Coordination Chemistry of Oxazoline‐Based Systems

Phosphorus-doped ordered mesoporous carbons (POMCs) with different lengths were synthesized using a metal-free nanocasting method of SBA-15 mesoporous silica with different sizes as template and triphenylphosphine and phenol as phosphorus and carbon sources, respectively. The resultant POMC with a small amount of P doping is demonstrated as a metal-free electrode with excellent electrocatalytic activity for oxygen reduction reaction (ORR), coupled with much enhanced stability and alcohol tolerance compared to those of platinum via four-electron pathway in alkaline medium. Interestingly, the POMC with short channel length is found to have superior electrochemical performances compared to those with longer sizes.

Phosphorus-doped ordered mesoporous carbons with different lengths as efficient metal-free electrocatalysts for oxygen reduction reaction in alkaline media.

https://iris.unive.it/bitstream/10278/13768/1/1994%20JOrganomet%20Chem.pdf

New aspects of the carbonylation of allylpalladium complexes

The crystal and molecular structure of trans-bis(triphenylphosphine)dicarbonyl(1,3-diphenylformamidino)rhenium(I)

The selective hydrogenation of ethyl-benzoylacetate to 3-hydroxy-3-phenyl-propionate catalyzed by Pd/C in EtOH in a solution of KOH has been investigated. Mass transfers as well as adsorption and desorption stages do not influence reaction kinetics. A kinetic model is proposed based on the best fitting of the experimental data with Langmuir–Hinshelwood type kinetics equation. The mechanism implies that the enolate of the ethyl-benzoylacetate adsorbs strongly on two sites, thus occupying a large part of the surface Pd atoms without any reaction. The ethyl-benzoylacetate adsorbs also on two sites but with adsorption equilibrium constant almost three order of magnitude lower than that of the enolate anions. Also the hydrogen is poorly adsorbed, however, it forms Pd–H and reacts with the adsorbed keto-ester by a step hydrogenation mechanism in which the first hydride insertion is the rate-determining step. Furthermore, due to the low surface Pd–H availability and the fast desorption of the 3-hydroxy-3-phenyl-propionate the consecutive hydrogenolysis of the C–OH bond of the product is practically suppressed, thus achieving selectivity close to 100%.

/pdf/selective-hydrogenation-of-ethyl-benzoylacetate-to-3-hydroxy-hysk3wgu3y.pdf

Selective hydrogenation of ethyl-benzoylacetate to 3-hydroxy-3-phenyl-propionate catalyzed by Pd/C in EtOH as a solvent in the presence of KOH: The role of the enolate ion on the reaction mechanism

Luigi Toniolo

Papers

New aspects of the carbonylation of allylpalladium complexes

The crystal and molecular structure of trans-bis(triphenylphosphine)dicarbonyl(1,3-diphenylformamidino)rhenium(I)

Selective hydrogenation of ethyl-benzoylacetate to 3-hydroxy-3-phenyl-propionate catalyzed by Pd/C in EtOH as a solvent in the presence of KOH: The role of the enolate ion on the reaction mechanism

Oxidative carbonylation of ethene catalyzed bi Pd(II)-PPh3 complexes in MeOH using benzoquinone as stoichiometric oxidant

Synthesis of γ-ketocarboxylic acids via reduction of γ-keto-α-hydroxycarboxylic acids with carbon monoxide catalyzed by a PdHCl system