The Space Confinement Approach Using Hollow Graphitic Spheres to Unveil Activity and Stability of Pt‐Co Nanocatalysts for PEMFC

Pizzutilo, Enrico; Knossalla, Johannes; Geiger, Simon; Grote, Jan-Philipp; Polymeros, George; Baldizzone, Claudio; Mezzavilla, Stefano; Ledendecker, Marc; Mingers, Andrea Maria; Cherevko, Serhiy; Schüth, Ferdi; Mayrhofer, Karl Johann Jakob

doi:10.1002/aenm.201700835

Cited by 52 publications

(47 citation statements)

References 66 publications

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“…The adoption of advanced catalyst supports with high conductivity, sufficient corrosion resistance and strong chemical interactions can offer an additional degree of freedom to tune the ORR catalysts . The electrocatalysts can be supported on various carbon materials such as carbon black, hollow graphitic spheres (HGS), carbon nanotubes (CNTs) and reduced graphene oxide (rGO) or its functional derivatives as well as noncarbonaceous materials . Selective carbon or noncarbon supports can introduce synergistic catalytic effect between nanocatalysts and the supporting substrate.…”

Section: Nanoscale Structure Design For High‐performance Pt‐based Orrmentioning

confidence: 99%

Nanoscale Structure Design for High‐Performance Pt‐Based ORR Catalysts

et al. 2018

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Since testing a given catalyst through the way of a membrane electrode assembly (MEA) is quite intricate and time-consuming, a simplified alternative approach to determine the ORR activity of a catalyst is using a rotating disc electrode (RDE) system. [2] The RDE system is a widely adopted convective system, in which the rotating of the working electrode generates convection of electrolyte to alleviate the mass transfer issue of reactants. [3] A typical ORR measurement using an RDE system includes Proton-exchange-membrane fuel cells (PEMFCs) are of considerable interest for direct chemical-to-electrical energy conversion and may represent an ultimate solution for mobile power supply. However, PEMFCs today are primarily limited by the sluggish kinetics of the cathodic oxygen reduction reaction (ORR), which requires a significant amount of Pt-based catalyst with a substantial contribution to the overall cost. Hence, promoting the activity and stability of the needed catalyst and minimizing the amount of Pt loaded are central to reducing the cost of PEMFCs for commercial deployment. Considerable efforts have been devoted to improving the catalytic performance of Pt-based ORR catalysts, including the development of various Pt nanostructures with tunable sizes and chemical compositions, controlled shapes with selectively displayed crystallographic surfaces, tailored surface strains, surface doping, geometry engineering, and interface engineering. Herein, a brief introduction of some fundamentals of fuel cells and ORR catalysts with performance metrics is provided, followed by a detailed description of a series of strategies for pushing the limit of high-performance Pt-based catalysts. A brief perspective and new insights on the remaining challenges and future directions of Pt-based ORR catalysts for fuel cells are also presented.

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Section: Nanoscale Structure Design For High‐performance Pt‐based Orrmentioning

confidence: 99%

Nanoscale Structure Design for High‐Performance Pt‐Based ORR Catalysts

et al. 2018

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“…Owing to the easy‐to‐manipulate microstructure and delimited local voids, researchers recently have demonstrated that elaborated hollow nano/microstructures exhibit superior performance as the primary materials in a variety of emerging research fields, such as catalysis, lithium‐ion batteries (LIBs), supercapacitors, proton‐exchange‐membrane fuel cells (PEMFCs), chemical sensors, and biomedicine . Along with tremendous progress on microstructural characterizations and basic growth mechanism of nanocrystals, hollow nanomaterials become one of the hot spots in the modern research of nanoscience, particularly focusing on the development of synthetic methodologies and structure‐correlated properties …”

Section: Introductionmentioning

confidence: 99%

“…and enrich the functions (e.g., magnetic separation, stimuli‐responsive, tandem catalysis, etc. ), several functionalization synthetic methods have been applied to upgrade simplex hollow building blocks to complex hierarchical structures: ship‐in‐a‐bottle methods are applied for the synthesis of encapsulated hollow structures to disperse and stabilize the catalytic sites; multistep template methods are used for the synthesis of multishelled hollow structures to increase the number of active sites; pyrolysis of metal–organic polymers for single atom site hollow structures maximizes the exposure of metal atoms to promote the overall activity; surface molecular modification of hybrid hollow structures at diverse spatial sites enables the catalysis of tandem reactions on the integrated multiple reaction sites …”

Section: Introductionmentioning

confidence: 99%

Functionalization of Hollow Nanomaterials for Catalytic Applications: Nanoreactor Construction

et al. 2018

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Hollow nanomaterials have attracted a broad interest in multidisciplinary research due to their unique structure and preeminent properties. Owing to the high specific surface area, well-defined active site, delimited void space, and tunable mass transfer rate, hollow nanostructures can serve as excellent catalysts, supports, and reactors for a variety of catalytic applications, including photocatalysis, electrocatalysis, heterogeneous catalysis, homogeneous catalysis, etc. Based on state-of-the-art synthetic methods and characterization techniques, researchers focus on the purposeful functionalization of hollow nanomaterials for catalytic mechanism studies and intricate catalytic reactions. Herein, an overview of current reports with respect to the catalysis of functionalized hollow nanomaterials is given, and they are classified into five types of versatile strategies with a top-down perspective, including textual and composition modification, encapsulation, multishelled construction, anchored single atomic site, and surface molecular engineering. In the detailed case studies, the design and construction of hierarchical hollow catalysts are discussed. Moreover, since hollow structure offers more than two types of spatial-delimited sites, complicated catalytic reactions are elaborated. In summary, functionalized hollow nanomaterials provide an ideal model for the rational design and development of efficient catalysts.

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“…[17][18][19][20][21][22][23] In a series of papers, Mayrhofer and co-workers showed that during potential cycling with UPL higher than 1.1 V, greater Pt dissolution occurs during the cathodic scan than during the anodic scan. 17,21,22 The amount of Pt dissolved during the cathodic scan increased with increasing UPL as well as with decreasing scan rate and occurred at potentials below 1 V in the cathodic scan.…”

mentioning

confidence: 99%

Potential Dependence of Pt and Co Dissolution from Platinum-Cobalt Alloy PEFC Catalysts Using Time-Resolved Measurements

Ahluwalia

Papadias

Kariuki

et al. 2018

J. Electrochem. Soc.

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An electrochemical flow cell system with catalyst-ionomer ink deposited on glassy carbon is used to investigate the aqueous stability of commercial PtCo alloys under cyclic potentials. An on-line inductively coupled plasma-mass spectrometer, capable of real-time measurements, is used to resolve the anodic and cathodic dissolution of Pt and Co during square-wave and triangle-wave potential cycles. We observe Co dissolution at all potentials, distinct peaks in anodic and cathodic Pt dissolution rates above 0.9 V, and potential-dependent Pt and Co dissolution rates. The amount of Pt that dissolves cathodically is smaller than the amount that dissolves anodically if the upper potential limit (UPL) is lower than 0.9 V. At the highest UPL investigated, 1.0 V, the cathodic dissolution greatly exceeds the anodic dissolution. A non-ideal solid solution model indicates that the anodic dissolution can be associated with the electrochemical oxidation of Pt and PtOH to Pt 2+ , and the cathodic dissolution to electrochemical reduction of a higher Pt oxide, PtO x (x > 1), to Pt 2+ . Pt also dissolves oxidatively during the cathodic scans but in smaller amounts than due to the reductive dissolution of PtO x . The relative amounts Pt dissolving oxidatively as Pt and PtOH depend on the potential cycle and UPL.

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The Space Confinement Approach Using Hollow Graphitic Spheres to Unveil Activity and Stability of Pt‐Co Nanocatalysts for PEMFC

Cited by 52 publications

References 66 publications

Nanoscale Structure Design for High‐Performance Pt‐Based ORR Catalysts

Nanoscale Structure Design for High‐Performance Pt‐Based ORR Catalysts

Functionalization of Hollow Nanomaterials for Catalytic Applications: Nanoreactor Construction

Potential Dependence of Pt and Co Dissolution from Platinum-Cobalt Alloy PEFC Catalysts Using Time-Resolved Measurements

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