The colloidal tool-box approach for fuel cell catalysts: Systematic study of perfluorosulfonate-ionomer impregnation and Pt loading

Spéder, József; Zana, Alessandro; Arenz, Matthias

doi:10.1016/j.cattod.2015.09.021

Cited by 28 publications

(24 citation statements)

References 51 publications

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“…This formulation includes the way the catalysts are washed, re‐dispersed and deposited for electrochemical assessment. These steps can strongly affect the activity measured for what is initially a same catalytic material . This is observed here with the higher activity obtained with Ir‐no‐PVP catalyst washed with HCl vs .…”

Section: Figurementioning

confidence: 65%

Synthesis of Iridium Nanocatalysts for Water Oxidation in Acid: Effect of the Surfactant

et al. 2020

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Proton exchange membrane water electrolysers are very promising renewable energy conversion devices to produce hydrogen from sustainable feedstocks. These devices are mainly limited by the sluggish kinetics of the oxygen evolution reaction (OER). Therefore, efficient catalysts in acidic media that allow operating at low overpotential are necessary. Ir‐based nanoparticles are both active and stable for the OER. Surfactants are widely used in the preparation of nanoparticle colloids. A severe drawback for catalysis is the need to remove surfactants by typically costly, hazardous, time and/or energy consuming steps. Herein we present a modified approach of the polyol synthesis that consists of a simple surfactant‐free and NaOH‐free synthesis of Ir nanoparticles in ethylene glycol leading to colloidal nanoparticles of ca. 2.5 nm in diameter. The benefits and drawbacks of the surfactant‐free synthesis are illustrated by comparison with commercial Ir black nanoparticles and Ir nanoparticles obtained using surfactant for the electrocatalytic OER in acidic media.

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Section: Figurementioning

confidence: 65%

Synthesis of Iridium Nanocatalysts for Water Oxidation in Acid: Effect of the Surfactant

et al. 2020

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“…A dispersion was considered stable if the supernatant maintained a brown or dark color and no significant sedimentation of NPs was observed at the bottom of the vials. The concentration of Pt NPs typically used for redispersion varies between 0.1 and 0.5 g L −1 based on inductively coupled plasma mass spectrometry (ICP‐MS) measurements performed as previously documented …”

Section: Methodsmentioning

confidence: 99%

“…The concentration of Pt NPs typically used for redispersion varies between 0.1 and 0.5 gL À1 based on inductively coupled plasma mass spectrometry (ICP-MS) measurements performed as previously documented. [51] XAS measurements:X -ray absorption spectroscopy (XAS) measurements were performed at the Diamond Light Source (DLS), UK and Swiss Light Source, Switzerland, by using the B18 and Super-XAS beam line, respectively.T he storage ring of the DLS and SLS was operated at ab eam current of 300 and 400 mA, respectively, and the storage ring energies were 3.0 and 2.4 GeV,r espectively. At the B18 beam line, the Pt L 3 egde XAS spectra were recorded in fluorescence mode by using a9element Ge solid-state detector system, whereas the acquisition of the Pt L 3 edge XAS spectra was performed in transmission mode at the SuperXAS beam line by using N 2 -filled ionization chambers with lengths of 15 and 30 cm for the incident (I 0 )a nd transmitted (I 1 and I 2 )X -ray intensities.…”

Section: Methodsmentioning

confidence: 99%

Controlled Synthesis of Surfactant‐Free Water‐Dispersible Colloidal Platinum Nanoparticles by the Co4Cat Process

et al. 2019

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The recently reported Co4Cat process is a synthesis method bearing ecological and economic benefits to prepare precious‐metal nanoparticles (NPs) with optimized catalytic properties. In the Co4Cat process, a metal precursor (e.g., H2PtCl6) is dissolved in an alkaline solution of a low‐boiling‐point solvent (methanol) and reduced to NPs at low temperature (<80 °C) without the use of surfactants. Here, the Co4Cat process to prepare Pt NPs is described in detail. The advantages of this new synthesis method for research and development but also industrial production are highlighted in a comparison with the popular “polyol” synthesis. The reduction of H2PtCl6 from PtIV to PtII and further to Pt0 is followed by UV/Vis and XANES/EXAFS measurements. It is demonstrated how the synthesis can be accelerated, how size control is achieved, and how the colloidal dispersions can be stabilized without the use of surfactants. Despite being surfactant‐free, the Pt NPs exhibit surprisingly long‐term (up to 16 months) stability in water over a wide pH range (4–12) and in aqueous buffer solutions. The Co4Cat process is thus relevant to produce NPs for heterogeneous catalysis, electro‐catalysis, or bio/medical applications.

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“…[1][2][3][4][5][6][7][8][9][10][11][12][13][14] for an overview. Most studies are related to surface science and therefore target the structure sensitivity of anion adsorption on well-defined single crystal surfaces.…”

Section: Introductionmentioning

confidence: 99%

On the oxygen reduction reaction in phosphoric acid electrolyte: Evidence of significantly increased inhibition at steady state conditions

Deng

Wiberg

Zana

et al. 2016

Electrochimica Acta

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In the presented work, we investigate the oxygen reduction reaction (ORR) in half-cell measurements employing different electrolytes. The aim is to compare the ORR inhibition due to anion adsorption at transient as well as steady state conditions. It is found that the ORR inhibition at the platinum -phosphoric acid electrolyte interface is a relative slow, time dependent process. The major inhibition is not observed in transient polarization curves but only under steady state 2 conditions. This observation is in contrast to the typical ORR inhibition due to anion adsorption as observed for example in sulfuric acid electrolyte. In sulfuric acid the inhibition is fast and then stays more or less constant in time. As a consequence of our findings, common transient measurements of the ORR activity might not be sufficient to investigate suitable mitigation strategies for the ORR inhibition in phosphoric acid electrolyte. Such strategies need to take steady state conditions into account.In order to explain the slow ORR inhibition in phosphoric acid electrolyte, two possible explanations are discussed. Either the adsorption of phosphate is a slow, complex process, where a fast adsorption step is followed by a consecutive filling of the surface, or a mass transfer barrier develops at the polarized phosphoric acid -electrode interface. The latter might be the viscoelectric effect that is known from colloidal science.

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The colloidal tool-box approach for fuel cell catalysts: Systematic study of perfluorosulfonate-ionomer impregnation and Pt loading

Cited by 28 publications

References 51 publications

Synthesis of Iridium Nanocatalysts for Water Oxidation in Acid: Effect of the Surfactant

Synthesis of Iridium Nanocatalysts for Water Oxidation in Acid: Effect of the Surfactant

Controlled Synthesis of Surfactant‐Free Water‐Dispersible Colloidal Platinum Nanoparticles by the Co4Cat Process

On the oxygen reduction reaction in phosphoric acid electrolyte: Evidence of significantly increased inhibition at steady state conditions

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