How to determine accurate chemical ordering in several nanometer large bimetallic crystallites from electronic structure calculations

Kozlov, Sergey M.; Kovács, Gâbor; Ferrando, Riccardo; Neyman, Konstantin M.

doi:10.1039/c4sc03321c

Cited by 73 publications

(160 citation statements)

References 112 publications

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“…Bimetallic TMCs using earth-abundant and cheap metals, such as Fe3Mo3C or Ni6Mo6C, have been previously prepared, via stepwise reduction of precursor oxides, 27 opening the path towards an economically reasonable synthesis procedure. Moreover, there have been clear improvements in the understanding of nanoalloys, 28 thus opening the door to future control.…”

Section: Introductionmentioning

confidence: 99%

Tuning transition metal carbide activity by surface metal alloying: a case study on CO₂capture and activation

López

Broderick

Carey

et al. 2018

Phys. Chem. Chem. Phys.

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CO2 is one of the main actors in the greenhouse effect and its removal from the atmosphere is becoming an urgent need. Thus, CO2 capture and storage (CCS) and CO2 capture and usage (CCU) are intensively investigated technologies to decrease the concentration of atmospheric CO2. Both CCS and CCU require appropriate materials to adsorb/release and adsorb/activate CO2, respectively. Recently, it has been theoretically and experimentally shown that transition metal carbides (TMC) are able to capture, store, and activate CO2. To further improve the adsorption capacity of these materials, a deep understanding of the atomic level processes involved is essential. In the present work, we theoretically investigate the possible effects of surface metal doping of these TMCs by taking TiC as a textbook case and Cr, Hf, Mo, Nb, Ta, V, W, and Zr as dopants. Using periodic slab models with large supercells and state-of-the-art density functional theory based calculations we show that CO2 adsorption is enhanced by doping with metals down a group but worsened along the d series. Adsorption sites, dispersion and coverage appear to play a minor, secondary constant effect. The dopant-induced adsorption enhancement is highly biased by the charge rearrangement at the surface. In all cases, CO2 activation is found but doping can shift the desorption temperature by up to 135 K.

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Section: Introductionmentioning

confidence: 99%

Tuning transition metal carbide activity by surface metal alloying: a case study on CO₂capture and activation

López

Broderick

Carey

et al. 2018

Phys. Chem. Chem. Phys.

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“…Moreover, the proposed mechanism can be confirmed by comparing the nanoparticles grown at room temperature with the ones grown at 60°C, as the latter ones seem to be ''swollen'' due to the formation of pores. From the literature it is known that, at higher temperatures, the optimal system energy has higher values than at lower temperatures [32], while the lowest system energy exhibit small, spherical nanoparticles. Therefore, when the synthesis temperature increases leading to the formation of bigger AuHP NPs, their pores become smaller to lower system energy [33].…”

Section: Resultsmentioning

confidence: 99%

Temperature-controlled synthesis of hollow, porous gold nanoparticles with wide range light absorption

et al. 2020

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An easy synthesis method of hollow, porous gold nanoparticles (AuHP NPs) with controlled diameter and pores sizes and with a wide range of light absorbance (continuous between 500 and 900 nm) is presented together with the explanation of the nanoparticle formation mechanism. The NPs were investigated using transmission electron microscopy (TEM) combined with the selected area electron diffraction patterns, X-ray diffraction and ultraviolet-visible spectroscopy. TEM images showed that changing the synthesis temperature allows to obtain AuHP NPs with sizes from 35 ± 4 nm at 60°C to 76 ± 8 nm at 90°C. The effects of nanoscale porosity on the far-and near-field optical properties of the nanoparticles, as well as on effective conversion of electromagnetic energy into thermal energy, were applied in simulated photothermal cancer therapy. The latter one was simulated by irradiation of two cancer cell lines SW480 and SW620 with lasers operating at 650 nm and 808 nm wavelengths. The mortality of cells after using the synthesized AuHP NPs as photosensitizers is between 20 and 50% and increases with the decrease in the diameter of the AuHP NPs. All these attractive properties of the AuHP NPs make them find application in many biomedical studies.

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“…The latter approach was demonstrated to yield results very close to those obtained with the cut-off 415 eV. 36 In our previous calculations of Pt-Sn nanoparticles (NPs) the application of the latter larger cut-off resulted in an energy change less than 0.5 meV per atom. 18 The one-electron levels were smeared by 0.1 eV using the rst-order method of Methfessel and Paxton; 37 nally, converged energies were extrapolated to the zero smearing.…”

Section: Density Functional Calculationsmentioning

confidence: 89%

Steering the formation of supported Pt–Sn nanoalloys by reactive metal–oxide interaction

et al. 2016

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The formation of a supported Pt-Sn nanoalloy upon reactive metal-oxide interaction between Pt nanoparticles and a Sn-CeO 2 substrate has been investigated by means of synchrotron radiation photoelectron spectroscopy and resonant photoemission spectroscopy in combination with density functional modeling. It was found that Pt deposition onto a Sn-CeO 2 substrate triggers the reduction of Sn 2+ cations yielding Pt-Sn nanoalloys at 300 K under ultra-high vacuum conditions. Three distinct stages of Pt-Sn nanoalloy formation were identified associated with the growth of (I) ultra-small monometallic Pt particles on a Sn-CeO 2 substrate, (II) Pt-Sn nanoalloys on a Sn-CeO 2 substrate, and (III) Pt-Sn nanoalloys on a stoichiometric CeO 2 substrate. These findings suggest the existence of a critical size of monometallic Pt particles above which the formation of a Pt-Sn nanoalloy becomes favorable. In this respect, density functional modeling revealed a strong dependence of the formation energy of the Pt x Sn nanoalloy on the size of the Pt particle. Additionally, the thermodynamically favorable bulk and surface Pt/Sn stoichiometries were identified as two parameters that determine the composition of the supported Pt-Sn nanoalloys and limit the extraction of Sn 2+ from the Sn-CeO 2 substrate. Primarily, the formation of a bulk Pt 3 Sn alloy phase drives the growth of the Pt-Sn nanoalloy upon Pt deposition at 300 K. Upon annealing, Sn segregation on the surface of the Pt-Sn nanoalloy promotes further extraction of Sn 2+ until the thermodynamically stable Pt/Sn concentration ratios of 3for the bulk and approximately 1.6 for the surface are reached.

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How to determine accurate chemical ordering in several nanometer large bimetallic crystallites from electronic structure calculations

Abstract: The proposed method allows to efficiently determine the atomic arrangement in bimetallic nanoparticles based on electronic structure calculations and unravels the relationship between structural preferences of atoms and binding in nanoalloys.

Cited by 73 publications

References 112 publications

Tuning transition metal carbide activity by surface metal alloying: a case study on CO₂capture and activation

Tuning transition metal carbide activity by surface metal alloying: a case study on CO₂capture and activation

Temperature-controlled synthesis of hollow, porous gold nanoparticles with wide range light absorption

Steering the formation of supported Pt–Sn nanoalloys by reactive metal–oxide interaction

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How to determine accurate chemical ordering in several nanometer large bimetallic crystallites from electronic structure calculations

Abstract: The proposed method allows to efficiently determine the atomic arrangement in bimetallic nanoparticles based on electronic structure calculations and unravels the relationship between structural preferences of atoms and binding in nanoalloys.

Cited by 73 publications

References 112 publications

Tuning transition metal carbide activity by surface metal alloying: a case study on CO2capture and activation

Tuning transition metal carbide activity by surface metal alloying: a case study on CO2capture and activation

Temperature-controlled synthesis of hollow, porous gold nanoparticles with wide range light absorption

Steering the formation of supported Pt–Sn nanoalloys by reactive metal–oxide interaction

Contact Info

Product

Resources

About

Tuning transition metal carbide activity by surface metal alloying: a case study on CO₂capture and activation

Tuning transition metal carbide activity by surface metal alloying: a case study on CO₂capture and activation