Density functional study of single-wall and double-wall platinum nanotubes

Konar, Shyamal; Gupta, Bikash C.

doi:10.1103/physrevb.78.235414

Cited by 22 publications

(28 citation statements)

References 47 publications

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“…7 Such single-wall helical nanotubes and helical multishell nanowires have been intensively fabricated experimentally and investigated theoretically not just for Au 1,[5][6][7][11][12][13][14][15][16] but also for various metals (e.g., Ag, Pt, Na, Rh, Zr, Ti, Pb, and ferromagnetic Ni). 2,3,[17][18][19][20][21][22][23][24] These studies have reported that the nanotubes and nanowires possess distinct mechanical and electronic properties originating from their helical shell structure, including superplasticity, 3 quantum ballistic conductance, 4 and helical conduction channels (which potentially could be used to fabricate nanosolenoid). 1,2 However, to the best of our knowledge, there has been no detailed study on the magnetism of helical nickel nanotubes or nanowires.…”

Section: Introductionmentioning

confidence: 99%

“…In addition, the magnetism is expected to be strongly dependent on the tube chirality, because the nanotubes with different chiralities have different electronic states. 1,2,12,18 Thus, studying ferromagnetic nickel nanotubes should lead to a deeper understanding of magnetism in nanostructures.…”

Section: Introductionmentioning

confidence: 99%

“…Theoretical studies based on ab initio (first-principles) density functional theory (DFT) calculations have successfully provided comprehensive insight into both the stability of metallic nanotubes 1,2,11,18 and the magnetic properties of various nanostructures. [25][26][27][28] In this study, we perform DFT calculations to investigate the magnetism as well as structural, energetic, and electronic properties in nickel single-wall nanotubes.…”

Section: Introductionmentioning

confidence: 99%

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Ab initiostudy of ferromagnetic single-wall nickel nanotubes

2011

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We performed ab initio spin-density functional theory calculations of the magnetic and electronic properties of ferromagnetic single-wall nickel nanotubes with various chiralities. A (6,3) nanotube was found to have an energetically favorable "magic" structure and consequently it is expected to be observed experimentally for both free-standing and tip-suspended conditions, whereas a (5,3) nanotube is expected to be observed only in the free-standing case. The (6,3) and (5,3) nanotubes, respectively, exhibit enhanced magnetic moments of 0.864 μ B and 0.774 μ B relative to 0.635 μ B in Ni bulk, because of their low coordination numbers. The dependence of the magnetic moment on the chirality is predominated by the minority-spin d xy and d zx states in which the out-of-plane d orbitals interact strongly with each other due to the nanotube curvature.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Ab initiostudy of ferromagnetic single-wall nickel nanotubes

2011

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confidence: 87%

“…In addition to widely-studied carbon nanotubes [7], chiral nanotubes have been formed from a range of other materials, including gold [5,8,9], platinum [10], silver [11], alkaline metals [12][13][14] and boron nitride [15,16]. These experimental observations have been supported by a range of theoretical investigations [17][18][19][20][21][22].It has recently been noted that the presence of intrinsic chiral electron currents in chiral nanotubes can be exploited to yield photogalvanic effects in heteropolar nanotubes [17], a new drive mechanism in carbon-nanotube windmills [23] and to produce internal magnetic fields in carbon nanotube solenoids [24] . In each of these examples, the underlying lattice is hexagonal, with two atoms per unit cell.…”

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confidence: 92%

Chiral currents in gold nanotubes

Manrique

Cserti²,

Lambert³

2010

Phys. Rev. B

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Results are presented for the electron current in gold chiral nanotubes (AuNTs). Starting from the band structure of (4, 3) and (5, 3) AuNTs, we find that the magnitude of the chiral currents are greater than those found in carbon nanotubes. We also calculate the associated magnetic flux inside the tubes and find this to be higher than the case of carbon nanotubes. Although (4,3) and (5,3) AuNTs carry transverse momenta of similar magnitudes, the low-bias magnetic flux carried by the former is far greater than that carried by the latter. This arises because the low-bias longitudinal current carried by a (4,3) AuNT is significantly smaller than that of a (5,3) AuNT.PACS numbers: 73.63. Nm, 73.63.Fg, 73.22.D Nanotubes and nanowires are of interest, not only because of their potential for deployment as interconnects, p-n junctions and rectifiers [1,2] in future nanoscale circuits, but also because they exhibit fundamental physical properties, such as conductance quantisation [3,4], and magic numbers reflecting structural stabilities [5,6]. One ubiquitous property associated with nanotubes is chirality, which arises because there is an infinite number of ways of rolling up a two-dimensional periodic lattice to form a cylinder. In addition to widely-studied carbon nanotubes [7], chiral nanotubes have been formed from a range of other materials, including gold [5,8,9], platinum [10], silver [11], alkaline metals [12][13][14] and boron nitride [15,16]. These experimental observations have been supported by a range of theoretical investigations [17][18][19][20][21][22].It has recently been noted that the presence of intrinsic chiral electron currents in chiral nanotubes can be exploited to yield photogalvanic effects in heteropolar nanotubes [17], a new drive mechanism in carbon-nanotube windmills [23] and to produce internal magnetic fields in carbon nanotube solenoids [24] . In each of these examples, the underlying lattice is hexagonal, with two atoms per unit cell. In contrast nanotubes formed from gold, silver and platinum are derived from triangular lattices with one atom per unit cell and therefore it is of interest examine whether or not these effects are enhanced or diminished compared with their carbon counterparts.In this paper, to answer these questions, we examine chiral currents in gold nanotubes. Our choice of gold is in part motivated by the fact that chiral currents are expected to scale with the Fermi velocity of the underlying two-dimensional lattice, which in gold is approximately double that of graphene.A nanotube formed from a 2D lattice with periodic boundary conditions can be described by a chiral vector C = na 1 + ma 2 , which defines the circumference of the nanotube, where a 1 , a 2 are the lattice vectors and n, m are integers. The axis of the nanotube lies parallel to the longitudinal translation vector T (which is perpendicular the the chiral vector), whose magnitude is equal to the length of the nanotube unit cell, along the tube axis. To understand the currents carried by such a nanotu...

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Synergetic Structural Transformation of Pt Electrocatalyst into Advanced 3D Architectures for Hydrogen Fuel Cells

Kim

et al. 2020

Advanced Materials

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oxidizing agent (oxygen). [4,5] Fuel cells are considered likely by many to play a central and integral role in future renewable energy developments. However, reducing their cost has been a significant challenge, and is critical for promoting future studies and accelerating market growth. [6-8] Currently, noble Pt materials are the most favored electrocatalysts for the electrochemical reactions at both the anode and cathode in fuel cells. The cathodic oxygen reduction reaction (ORR) rate is substantially slower than the anodic hydrogen oxidation reaction by several orders of magnitude. When properly tailored in electrodes, Pt materials provide fast reaction kinetics, good electrical conductivity, and high chemical stability in strongly acidic electrolytes. [9-11] Conventional electrocatalyst structures generally employ fine Pt powders (2-3 nm) supported on high surface area carbon (Pt/C). However, as the number of large scale energy applications continues to increase, the high required Pt loading (typically ≈0.5 mg cm −2 for commercial electrodes) and high cost of this precious metal (≈$1000 per troy ounce) pose significant barriers to the widespread use of fuel cells containing Pt materials. The quantity of Pt required to achieve the targeted electrode performance significantly contributes to the high cost of fuel cell systems. [12-14] In recent decades, significant efforts have been devoted to investigating the principles underlying the electrocatalyst layer, A new direction for developing electrocatalysts for hydrogen fuel cell systems has emerged, based on the fabrication of 3D architectures. These new architectures include extended Pt surface building blocks, the strategic use of void spaces, and deliberate network connectivity along with tortuosity, as design components. Various strategies for synthesis now enable the functional and structural engineering of these electrocatalysts with appropriate electronic, ionic, and electrochemical features. The new architectures provide efficient mass transport and large electrochemically active areas. To date, although there are few examples of fully functioning hydrogen fuel cell devices, these 3D electrocatalysts have the potential to achieve optimal cell performance and durability, exceeding conventional Pt powder (i.e., Pt/C) electrocatalysts. This progress report highlights the various 3D architectures proposed for Pt electrocatalysts, advances made in the fabrication of these structures, and the remaining technical challenges. Attempts to develop design rules for 3D architectures and modeling, provide insights into their achievable and potential performance. Perspectives on future developments of new multiscale designs are also discussed along with future study directions.

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Density functional study of single-wall and double-wall platinum nanotubes

Cited by 22 publications

References 47 publications

Ab initiostudy of ferromagnetic single-wall nickel nanotubes

Ab initiostudy of ferromagnetic single-wall nickel nanotubes

Chiral currents in gold nanotubes

Synergetic Structural Transformation of Pt Electrocatalyst into Advanced 3D Architectures for Hydrogen Fuel Cells

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