Thermodynamic properties of Pt nanoparticles: Size, shape, support, and adsorbate effects

Cuenya, Beatriz Roldán; Ortigoza, Marisol Alcántara; Ono, Luis K.; Behafarid, Farzad; Mostafa, Simón; Croy, Jason R.; Paredis, Kristof; Shafai, Ghazal; Rahman, Talat S.; Li, L.; Zhang, Z.; Yang, Judith C.

doi:10.1103/physrevb.84.245438

Cited by 50 publications

(83 citation statements)

References 70 publications

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“…Size-selected 57 Fe nanoparticles (NPs) were synthesized via inverse micelle encapsulation 52,53,59 . Non-polar/polar diblock copolymers [PS(x)-P2VP(y)] were dissolved in toluene (non-polar) to form reverse micelles and subsequently loaded with a 57 FeCl 3 salt.…”

Section: Methodsmentioning

confidence: 99%

“…Some examples of thermal quantities that are modified at the nanoscale are lattice specific heat (C v ) [5][6][7][8] , vibrational entropy (S vib ) 2, 4, 9, 10 , atomic mean square displacement (<x 2 >) and Debye temperature (Θ D ) [11][12][13][14][15] , thermal expansion 16,17 , melting temperature 18 , structural phase transitions involving soft phonon modes 28,29 , and thermally activated phenomena described by the pre-exponential factor 30 in Arrhenius-type processes on the surface of NPs (e.g. diffusion and surface chemical reactions 31 ).…”

Section: Introductionmentioning

confidence: 99%

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Size-dependent evolution of the atomic vibrational density of states and thermodynamic properties of isolated Fe nanoparticles

et al. 2012

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We have gained insight into the internal degree of atomic disorder in isolated sizeselected Fe nanoparticles (NPs) (~2 -6 nm in size) supported on SiO 2 /Si(111) and Al 2 O 3 (0001) from precise measurements of the low-energy (low-E) part of the phonon density of states [PDOS, g(E)] via 57 Fe nuclear resonant inelastic X-ray scattering (NRIXS), combined with transmission electron microscopy (TEM) measurements. An intriguing size-dependent trend was observed, namely, an increase of the low-E excess density of phonon states (as compared to the PDOS of bulk bcc Fe) with increasing NP size. This is unexpected, since usually the enhancement of the density of low-E phonon modes is attributed to low-coordinated atoms at the NP surface, whose relative content increases with decreasing NP size due to the increase in the surface-to-volume ratio. OurNPs are covered by a Ti coating layer, which essentially restores the local neighbourhood of surface Fe surface atoms towards bulk-like coordination, reducing the surface effect.Our data can be qualitatively explained by the existence of low-coordinated Fe atoms 2 located at grain boundaries or other defects with structural disorder in the interior of the large NPs (~3 -6 nm), while our small NPs (~2 nm) are single-grain and, therefore, characterized by a higher degree of structural order. This conclusion is corroborated by the observation of Debye behaviour at low energy [g(E) ~ E n with n ~ 2] for the small NPs, but non-Debye behaviour (with n ~ 1.4) for the large NPs. The PDOS was used to determine thermodynamic properties of the Fe NPs. Finally, our results demonstrate that, in combination with TEM, NRIXS is a suitable technique to investigate atomic disorder/defects in NPs. We anticipate that our findings are universal for similar NPs with bcc structure.Keywords: Fe, nanoparticle, nuclear resonant inelastic x-ray scattering, atomic force microscopy, transmission electron microscopy, x-ray photoelectron spectroscopy, phonon density of states.

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Size-dependent evolution of the atomic vibrational density of states and thermodynamic properties of isolated Fe nanoparticles

et al. 2012

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“…Theoretical, computational, and experimental studies have been performed to elucidate the melting mechanism as well as the exact dependency of the melting temperature on the particle diameter. The reported melting temperature of free‐standing metal nanoparticles is almost always linearly dependent on the inverse particle diameter ( T m ∼ d −1 ), see, e.g., the review by Nanda or the perspective by Li and Truhlar .…”

Section: Introductionmentioning

confidence: 99%

Size‐Dependence of the Melting Temperature of Individual Au Nanoparticles

Schlexer

Andersen

Sebők

et al. 2019

Part & Part Syst Charact

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Nanoparticles have an immense importance in various fields, such as medicine, catalysis, and various technological applications. Nanoparticles exhibit a significant depression in melting point as their size goes below ≈10 nm. However, nanoparticles are frequently used in high temperature applications such as catalysis where temperatures often exceed several 100 degrees which makes it interesting to study not only the melting temperature depression, but also how the melting progresses through the particle. Using high‐resolution transmission electron microscopy, the melting process of gold nanoparticles in the size range of 2–20 nm Au nanoparticles combined with molecular dynamics studies is investigated. A linear dependence of the melting temperature on the inverse particle size is confirmed; electron microscopy imaging reveals that the particles start melting at the surface and the liquid shell formed then rapidly expands to the particle core.

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“…Nanomaterials are gaining interest and prominence due to their many new-fangled properties in contrast to that in traditional bulk materials. Among the metal nanoparticles (NPs), transition metal NPs, in particular the nanoparticles of cobalt (Farhadi and Safabakhsh 2013), nickel (Abdelhalim et al 2012;Huang et al 2007Au, He et al 2013Nejati and Zabihi 2012;Wang et al 2008), palladium (Xiong et al 2005;Jana et al 2000); platinum (Roldan Cuenya et al 2011;Zhang et al 2008), gold (Merza1 et al 2012) and titanium (Mishra et al 2010), have attracted much attention of the researchers for a long time due to their size-induced properties and application-oriented importance in many industries as well as in advanced technologies. Among these transition metal nanoparticles, silver nanoparticles (Ag NPs) have been extensively studied due to their surface enhanced properties with fascinating structures and unique electrical, chemical, optical and antimicrobial properties.…”

Section: Introductionmentioning

confidence: 99%

Electrochemical synthesis, characterisation and phytogenic properties of silver nanoparticles

Singaravelan¹,

Alwar²

2015

Appl Nanosci

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This work exemplifies a simple and rapid method for the synthesis of silver nanodendrite with a novel electrochemical technique. The antibacterial activity of these silver nanoparticles (Ag NPs) against pathogenic bacteria was investigated along with the routine study of optical and spectral characterisation. The optical properties of the silver nanoparticles were characterised by diffuse reflectance spectroscopy. The optical band gap energy of the electrodeposited Ag NPs was determined from the diffuse reflectance using Kubelka-Munk formula. X-ray diffraction (XRD) studies were carried out to determine the crystalline nature of the silver nanoparticles which confirmed the formation of silver nanocrystals. The XRD pattern revealed that the electrodeposited Ag NPs were in the cubic geometry with dendrite preponderance. The average particle size and the peak broadening were deliberated using Debye-Scherrer equation and lattice strain due to the peak broadening was studied using Williamson-Hall method. Surface morphology of the Ag NPs was characterised by high-resolution scanning electron microscope and the results showed the high degree of aggregation in the particles. The antibacterial activity of the Ag NPs was evaluated and showed unprecedented level antibacterial activity against multidrug resistant strains such as Staphylococcus aureus, Bacillus subtilis, Klebsiella pneumonia and Escherichia coli in combination with Streptomycin.

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Thermodynamic properties of Pt nanoparticles: Size, shape, support, and adsorbate effects

Abstract: This study presents a systematic investigation of the thermodynamic properties of free and γ-

Cited by 50 publications

References 70 publications

Size-dependent evolution of the atomic vibrational density of states and thermodynamic properties of isolated Fe nanoparticles

Size-dependent evolution of the atomic vibrational density of states and thermodynamic properties of isolated Fe nanoparticles

Size‐Dependence of the Melting Temperature of Individual Au Nanoparticles

Electrochemical synthesis, characterisation and phytogenic properties of silver nanoparticles

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