Emerging Applications of Solid Catalysts with Ionic Liquid Layer Concept in Electrocatalysis

Zhang, Guirong; Etzold, Bastian J. M.

doi:10.1002/adfm.202010977

Cited by 27 publications

(20 citation statements)

References 123 publications

(303 reference statements)

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“…ILs are particularly interesting for catalytic applications. Two concepts have been developed and introduced, that is, the supported ionic liquid phase (SILP) approach [10,[22][23][24] and the solid catalyst with ionic liquid layer (SCILL) approach [24,25]. In SILP, an IL film containing dissolved transition metal complexes is coated onto a porous support, whereas in SCILL a thin IL film is coated onto the active metal surface of a heterogeneous catalyst [24].…”

Section: Introductionmentioning

confidence: 99%

Structure and Reactivity of the Ionic Liquid [C1C1Im][Tf2N] on Cu(111)

et al. 2023

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We studied the adsorption and reaction behavior of the ionic liquid (IL) 1,3-dimethylimidazolium bis[(trifluoromethyl)sulfonyl]imide ([C1C1Im][Tf2N]) on Cu(111) using non-contact atomic force microscopy (nc-AFM), scanning tunneling microscopy (STM), and angle-resolved X-ray photoelectron spectroscopy (ARXPS) in ultrahigh vacuum as a function of temperature, supported by density-functional theory (DFT) calculations. Our nc-AFM results for sub-monolayer IL films show that at 200 K, the IL self-assembles into highly ordered islands, with cations and anions arranged next to each other in a checkerboard–type phase. After extended annealing at 300 K, the structure transforms first to a hexagonal phase and then to a porous honeycomb phase. Simultaneously, many small, disordered islands are formed. Complementary ARXPS reveals no IL desorption until 300 K. However, a significant fraction of the IL is converted to a new species as deduced from new, strongly shifted peaks that develop in the XP spectra at around 275 K and grow with annealing time at 300 K. We correlate the remaining unshifted peaks to the ordered phases observed in nc-AFM and the shifted peaks to decomposition products, which appear as disordered islands in nc-AFM and STM. Upon further heating to 360 K, about 50% of the anions or their decomposition products desorb from the surface, while cation-related fragments mostly remain on the surface. From DFT, we obtain additional information on the structure of the ordered phases and the interaction of the IL with the substrate.

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Section: Introductionmentioning

confidence: 99%

Structure and Reactivity of the Ionic Liquid [C1C1Im][Tf2N] on Cu(111)

et al. 2023

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“…Sung’s and Miyabayashi’s groups modified a Pt catalyst with a small amount of amine-terminated organic molecules (octylamine, oleylamine, aniline, and hexamethylenediamine) and observed ORR activity enhancements. − They considered that the modification with the organic molecules changes the electronic state ( d -band center) of the catalyst NPs and suppresses the oxidation of the Pt surface, leading to the observed enhancement of the ORR activity. Snyder’s and Etzold’s groups demonstrated that the ORR activity of Pt and Pt alloy catalysts can be enhanced by decoration with ionic liquids (ILs). − They discussed the ORR activity enhancement in terms of a high oxygen solubility and a high hydrophobicity of the ILs.…”

Section: Introductionmentioning

confidence: 99%

A Strategy for Drastic Improvement in the Durability of Pt/C and PtCo/C Alloy Catalysts for the Oxygen Reduction Reaction by Melamine Surface Modification

et al. 2022

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A strategy for drastic improvement in the durability of a Pt/C catalyst and a PtCo/C alloy catalyst for the oxygen reduction reaction (ORR) by melamine surface modification was demonstrated. The durability of the catalysts was evaluated by an accelerated durability test (ADT) using a square wave potential cycling of 0.6–1.0 V vs RHE performed in Ar-saturated 0.1 mol dm–3 HClO4 containing a very small amount of melamine (10 μmol dm–3) at 80 °C for 10,000 cycles. Transmission electron microscopy (TEM) observations showed that melamine addition suppressed a size increase in the catalyst nanoparticles (NPs) during the ADT caused by the Ostwald ripening and/or migration-coalescence, which mitigated a loss in the electrochemical surface area of the catalysts. More importantly, TEM-EDX compositional analysis revealed that melamine addition suppressed Co dealloying of the PtCo NPs during the ADT and the alloy catalyst retained a high ORR mass activity of 1019 A g–1-Pt at 0.9 V vs RHE even after the ADT. The durability improvement is considered to arise from the suppression of Pt-oxygenated species formation caused by destabilization of a stable water molecule network formed on the catalyst surface and selective adsorption of melamine molecules at low-coordination surface Pt sites. Our results open up an alternative avenue for drastic improvement in the durability of the Pt-based catalysts for the ORR in polymer electrolyte fuel cells.

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“…[1][2][3][4][5] Ionic liquids are used as solvents in the processing of aerogels, as a silica supported catalyst in water and in other homogeneous and heterogeneous catalytic processes. [6][7][8][9][10][11][12] Concerning electrochemistry, they attract great attention as promising electrolytes in energy storage applications such as batteries and supercapacitors [13][14][15][16] and their associated charging dynamics have been extensively studied with molecular simulations. [17][18][19] However, the conductivity of ionic liquids is generally rather low 20 and can be increased by the addition of solvents that effectively reduce their viscosity.…”

Section: Introductionmentioning

confidence: 99%

Impact of confinement and polarizability on dynamics of ionic liquids

Gaeding

Tocci

Busch

et al. 2022

The Journal of Chemical Physics

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Polarizability is a key factor when it comes to an accurate description of different ionic systems. The general importance of including polarizability into molecular dynamics simulations was shown in various recent studies for a wide range of materials, ranging from proteins to water to complex ionic liquids and for solid-liquid interfaces. While most previous studies focused on bulk properties or static structure factors, this study investigates in more detail the importance of polarizable surfaces on the dynamics of a confined ionic liquid in graphitic slit pores, as evident in modern electrochemical capacitors or in catalytic processes. A recently developed polarizable force field using Drude oscillators is modified in order to describe a particular room temperature ionic liquid accurately and in agreement with recently published experimental results. Using the modified parameters, various confinements are investigated and differences between non-polarizable and polarizable surfaces are discussed. Upon introduction of surface polarizability, changes in the dipole orientation and in the density distribution of the anions and cations at the interface are observed and are also accompanied with a dramatic increase in the molecular diffusivity in the contact layer. Our results thus clearly underline the importance of considering not only the polarizability of the ionic liquid but also that of the surface.

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Emerging Applications of Solid Catalysts with Ionic Liquid Layer Concept in Electrocatalysis

Cited by 27 publications

References 123 publications

Structure and Reactivity of the Ionic Liquid [C1C1Im][Tf2N] on Cu(111)

Structure and Reactivity of the Ionic Liquid [C1C1Im][Tf2N] on Cu(111)

A Strategy for Drastic Improvement in the Durability of Pt/C and PtCo/C Alloy Catalysts for the Oxygen Reduction Reaction by Melamine Surface Modification

Impact of confinement and polarizability on dynamics of ionic liquids

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