Discovery of Face-Centered-Cubic Ruthenium Nanoparticles: Facile Size-Controlled Synthesis Using the Chemical Reduction Method

Kusada, Kohei; Kobayashi, Hirokazu; Yamamoto, Tomokazu; Matsumura, Shuichi; Sumi, Naoya; Sato, Katsutoshi; Nagaoka, Katsutoshi; Kubota, Yoshiki; Kitagawa, Hiroshi

doi:10.1021/ja311261s

Cited by 309 publications

(421 citation statements)

References 42 publications

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“…For example, it was found that FCC Ru catalysts were more catalytically active for CO oxidation than HCP Ru catalysts. 12 In summary, we identify theoretically that, for CO activation in the presence of hydrogen, HCP Co catalysts have remarkably higher intrinsic activity than FCC Co catalysts, and HCP Co catalysts prefer the direct dissociation route while FCC Co catalysts prefer the H-assisted route. The great influence of crystallographic structure and corresponding morphology effect on formation of the various active sites with higher intrinsic activity and density is illustrated.…”

Section: Journal Of the American Chemical Societymentioning

confidence: 73%

Crystallographic Dependence of CO Activation on Cobalt Catalysts: HCP versus FCC

et al. 2013

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Identifying the structure sensitivity of catalysts in reactions, such as Fischer−Tropsch synthesis from CO and H 2 over cobalt catalysts, is an important yet challenging issue in heterogeneous catalysis. Based on a first-principles kinetic study, we find for the first time that CO activation on hexagonal close-packed (HCP) Co not only has much higher intrinsic activity than that of face centered-cubic (FCC) Co but also prefers a different reaction route, i.e., direct dissociation with HCP Co but Hassisted dissociation on the FCC Co. The origin is identified from the formation of various denser yet favorable active sites on HCP Co not available for FCC Co, due to their distinct crystallographic structure and morphology. The great dependence of the activity on the crystallographic structure and morphology of the catalysts revealed here may open a new avenue for better, stable catalysts with maximum mass-specific reactivity.I dentifying the structure sensitivity of catalysts in chemical reactions to achieve the maximum mass-specific yet stable reactivity is one of the most challenging goals in heterogeneous catalysis. 1 A growing number of studies are conducted to understand the nature of the structure sensitivity, supported by well-defined preparation methods, in situ characterizations, surface science studies, and ab initio calculations. A prime example of this complex structure sensitivity is the Fischer− Tropsch synthesis (FTS) converting CO and H 2 from coal, natural gas, and biomass to hydrocarbon over cobalt catalysts. 2 Over the years, two notable structure sensitivities have been observed for FTS over Co catalysts, i.e., crystallographic structure and particle size. First, it is noted that Co can exist in two crystallographic structures, namely, the hexagonal closepacked (HCP) phase and the face-centered cubic (FCC) phase, and both phases are found in FTS. It has been reported by many that HCP Co has higher FTS activity than FCC Co. 3 This structure sensitivity is, however, complicated by a phase transition from HCP to FCC upon decreasing the catalyst size, 4 varying the supports and promoters, and pretreating the catalysts. 5 To our best knowledge, it remains open as to whether and why HCP Co catalysts have higher FTS activity than FCC ones, which prevents the full exploration of this structure sensitivity. Second, there are a number of reports on the effect of particle size of Co catalysts on FTS activity; namely, the turnover frequency (TOF) was constant for crystallites above a certain diameter, but when the diameter became smaller, the TOF decreased. 6 It is unclear whether the decrease of FTS activity at the smaller particle size is related to the phase transition of the Co catalyst from HCP to FCC, because of the complexity of the FTS and the absence of sufficient crystallographic structure data. Nevertheless, it is clear that one cannot increase the mass-specific activity of Co catalysts in FTS simply by decreasing the particle size.We report here a density functional theory (DFT)-base...

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Section: Journal Of the American Chemical Societymentioning

confidence: 73%

Crystallographic Dependence of CO Activation on Cobalt Catalysts: HCP versus FCC

et al. 2013

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“…An intriguing example are tens of nanometers large Co nanoparticles stabilized in the fcc phase at ambient conditions while bulk Co crystallizes in hexagonal close-packed (hcp) structure [4,7]. Besides cooling, other preparation routes like high-pressure torsion, milling, epitaxial growth, chemical reduction, and microwave irradiation have been proven fruitful to stabilize pure metals in non-equilibrium crystalline phases of their phase diagram (e.g., fcc Fe nanoparticles [8][9][10], fcc Co films [11]) or to reveal unique crystalline phases, i.e., phases not * stesch@kth.se † xiaoqli@kth.se known from their pressure-temperature phase diagram (e.g., nanoparticles of fcc Ru [12], fcc Zr [13], tetragonal Ag [14], fcc Hf [15], and bcc Co films [16]). The common interest that drives current research on such nanostructured materials is related to their potentially shape-or size-enhanced mechanical, magnetic, optical, electronic, or catalytic properties [17].…”

Section: Introductionmentioning

confidence: 99%

Metastable cubic and tetragonal phases of transition metals predicted by density-functional theory

Schönecker

Koepernik

et al. 2015

RSC Adv.

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By means of density-functional calculations, we systematically investigated 24 transition metals for possible metastable phases in body-centered tetragonal structure (bct), including face-centered cubic (fcc) and body-centered cubic (bcc) geometries. A total of 36 structures not coinciding with equilibrium phases were found to minimize the total energy for the bct degrees of freedom. Among these, the fcc structures of Sc, Ti, Co, Y, Zr, Tc, Ru, Hf, Re, and Os, and bct Zr with c/a = 0.82 were found to be metastable according to their computed phonon spectra. Eight of these predicted phases are not known from the respective pressure-temperature phase diagrams. Possible ways to stabilize the predicted metastable phases are illustrated.

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“…Sun et al [109] observed the crystal phase evolution of Fe-Pt alloys from fcc to face-centered tetragonal (fct) at high temperature during the synthesis. Afterwards, under controlled synthetic conditions, hexagonal close-packed (hcp, 2H type) and 4H Au, [87,110] body-centered tetragonal (bct) Ag [111], fcc Fe [112], hcp Ni [113], fcc Ru [114] and hcp Rh [99] nanostructures can be prepared. In addition, during some typical growth stages such as seed growth, ligand exchange, and metal coating, the unusual phase or phase evolution can be also observed.…”

Section: Phase Evolutionmentioning

confidence: 99%

Understanding of the major reactions in solution synthesis of functional nanomaterials

Wang

2016

Sci. China Mater.

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This review covers the major reactions involved in the solution synthesis of nanomaterials. It was designed to classify the traditional strategies such as precipitation, reduction, seed growth, etching, and so on into two basic processes which are termed as bottom-up and top-down routines. The discussion is focused on the basic mechanism and principles during the nucleation and growth of nanocrystals, especially in the solution system. This review also presents a prediction for how to utilize these intrinsic processes to artificially construct the desired specific and functional nanostructures. We try to describe the most directive and effective way to control the structures of nanocrystals for researchers who can master the major reaction mechanism and grasp the basic technologies in synthetic nanoscience.

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Discovery of Face-Centered-Cubic Ruthenium Nanoparticles: Facile Size-Controlled Synthesis Using the Chemical Reduction Method

Cited by 309 publications

References 42 publications

Crystallographic Dependence of CO Activation on Cobalt Catalysts: HCP versus FCC

Crystallographic Dependence of CO Activation on Cobalt Catalysts: HCP versus FCC

Metastable cubic and tetragonal phases of transition metals predicted by density-functional theory

Understanding of the major reactions in solution synthesis of functional nanomaterials

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