Research

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16 pages, 2409 KiB

Open AccessArticle

Toward Overcoming the Challenges in the Comparison of Different Pd Nanocatalysts: Case Study of the Ethanol Oxidation Reaction

by Oliver Asger Hjortshøj Schreyer, Jonathan Quinson and María Escudero-Escribano

Inorganics 2020, 8(11), 59; https://0-doi-org.brum.beds.ac.uk/10.3390/inorganics8110059 - 28 Oct 2020

Cited by 8 | Viewed by 2353

Abstract

Precious metal nanoparticles, in particular palladium nanomaterials, show excellent catalytic properties and are key in the development of energy systems. For instance, ethanol fuel cells are promising devices for sustainable energy conversion, where Pd-based catalysts are key catalysts for the related ethanol oxidation [...] Read more.

Precious metal nanoparticles, in particular palladium nanomaterials, show excellent catalytic properties and are key in the development of energy systems. For instance, ethanol fuel cells are promising devices for sustainable energy conversion, where Pd-based catalysts are key catalysts for the related ethanol oxidation reaction (EOR). Pd is a limited resource; thus, a remaining challenge is the development of efficient and stable Pd-based catalysts. This calls for a deeper understanding of the Pd properties at the nanoscale. This knowledge can be gained in comparative studies of different Pd nanomaterials. However, such studies remain challenging to perform and interpret due to the lack of cross-studies using the same Pd nanomaterials as a reference. Here, as-prepared sub 3 nm diameter surfactant-free Pd nanoparticles supported on carbon are obtained by a simple approach. The as-prepared catalysts with Pd loading 10 and 30 wt % show higher activity and stability compared to commercially available counterparts for the EOR. Upon electrochemical testing, a significant size increase and loss of electrochemical active surface are observed for the as-prepared catalysts, whereas the commercial samples show an increase in the electrochemically active surface area and moderate size increase. This study shines light on the challenging comparison of different catalysts across the literature. Further advancement in Pd (electro)catalyst design will gain from including self-prepared catalysts. The simple synthesis detailed easily leads to suitable nanoparticles to be used as a reference for more systematic comparative studies of Pd catalysts across the literature. Full article

(This article belongs to the Special Issue Palladium Catalysts: From Design to Applications)

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Review

Jump to: Research

14 pages, 11258 KiB

Open AccessReview

Bulky-Yet-Flexible Carbene Ligands and Their Use in Palladium Cross-Coupling

by Sofie M. P. Vanden Broeck, Fady Nahra and Catherine S. J. Cazin

Inorganics 2019, 7(6), 78; https://0-doi-org.brum.beds.ac.uk/10.3390/inorganics7060078 - 21 Jun 2019

Cited by 26 | Viewed by 5364

Abstract

In recent years, several classes of new N-heterocyclic carbene (NHC) ligands were developed around the concept of “flexible steric bulk”. The steric hindrance of these ligands brings stability to the active species, while ligand flexibility still allows for the approach of the [...] Read more.

In recent years, several classes of new N-heterocyclic carbene (NHC) ligands were developed around the concept of “flexible steric bulk”. The steric hindrance of these ligands brings stability to the active species, while ligand flexibility still allows for the approach of the substrate. In this review, the synthesis of several types of new classes, such as IBiox, cyclic alkyl amino carbenes (CAAC), ITent, and IPr* are discussed, as well as how they move the state-of-the-art in palladium catalyzed cross-coupling forward. Full article

(This article belongs to the Special Issue Palladium Catalysts: From Design to Applications)

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24 pages, 4073 KiB

Open AccessReview

Electrocatalytic Activities towards the Electrochemical Oxidation of Formic Acid and Oxygen Reduction Reactions over Bimetallic, Trimetallic and Core–Shell-Structured Pd-Based Materials

by Takao Gunji and Futoshi Matsumoto

Inorganics 2019, 7(3), 36; https://0-doi-org.brum.beds.ac.uk/10.3390/inorganics7030036 - 07 Mar 2019

Cited by 23 | Viewed by 5247

Abstract

The structural design of nanosized electrocatalysts is extremely important for cathodic oxygen reduction reactions (ORR) and anodic oxidation reactions in small organic compounds in direct fuel cells. While Pt is still the most commonly used electrode material for ORR, the Pd electrocatalyst is [...] Read more.

The structural design of nanosized electrocatalysts is extremely important for cathodic oxygen reduction reactions (ORR) and anodic oxidation reactions in small organic compounds in direct fuel cells. While Pt is still the most commonly used electrode material for ORR, the Pd electrocatalyst is a promising alternative to Pt, because it exhibits much higher electrocatalytic activity towards formic acid electrooxidation, and the electrocatalytic activity of ORR on the Pd electrode is the higher than that of all other precious metals, except for Pt. In addition, the mass activity of Pt in a core–shell structure for ORR can be improved significantly by using Pd and Pd-based materials as core materials. Herein, we review various nanoscale Pd-based bimetallic, trimetallic and core–shell electrocatalysts for formic acid oxidation and ORR of polymer electrolyte fuel cells (PEFCs). This review paper is separated into two major topics: the electrocatalytic activity towards formic acid oxidation over various Pd-based electrocatalysts, and the activity of ORR on Pd-based materials and Pd core–Pt shell structures. Full article

(This article belongs to the Special Issue Palladium Catalysts: From Design to Applications)

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