Local structure study of the Ni nanoparticles embedded in SiO2 by ion implantation

Zhang, Xiaojian; Wang, Yuhua; Chen, Huajian; Zheng, Lirong

doi:10.1016/j.jallcom.2015.09.139

Cited by 3 publications

(2 citation statements)

References 13 publications

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“…The metal–oxygen bond distances were R Ni–O = 2.030 ± 0.009 Å and R Co–O = 2.035 ± 0.016 Å for the 7.5Co–7.5Ni catalyst and R Co–O = 2.047 ± 0.008 Å for the 15Co catalyst. Second shell metal–metal scattering characteristic of CoO or NiO structures was not observed, while the metal–oxygen scattering bond distances were significantly shorter than for the corresponding bulk species ( R Co–O = 2.095 ± 0.008 Å; R Ni–O = 2.080 ± 0.006 Å). − These lower metal–oxygen bond distances, together with no significant presence of metal–metal (M–M) scattering derived from the oxide component, suggested the interaction of oxygen with the metal nanoparticle surfaces. , The M–M coordination numbers for the 7.5Co7.5Ni catalyst, obtained at the Co and Ni K-edges, could be considered to be in the same range, with a Co–Co bond distance ( R Co–Co ) of 2.499 ± 0.001 Å and a Ni–Ni bond distance ( R Ni–Ni ) of 2.488 ± 0.002 Å. These bond distances obtained for the 7.5Co7.5Ni bimetallic catalyst were lower than for the 15Co catalyst ( R Co–Co = 2.509 ± 0.001 Å) but were similar to those found for the monometallic 15Ni sample ( R Ni–Ni = 2.488 ± 0.003 Å).…”

Section: Resultsmentioning

confidence: 96%

Steam Reforming of Ethanol Using Ni–Co Catalysts Supported on MgAl₂O₄: Structural Study and Catalytic Properties at Different Temperatures

et al. 2021

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A spectroscopic and microscopic investigation was made of the dynamics of bimetallic nanoparticles (NPs) in Co− Ni/MgAl 2 O 4 catalysts used for the steam reforming of ethanol (SRE) reaction, considering the implications for catalytic performance, shedding light on the elusive effect of Co−Ni alloy in reforming reactions. X-ray absorption spectroscopy (XAS) analyses showed that contact with the reagent mixture led to major changes in the superficial structure of the Co−Ni nanoparticles, which were strongly dependent on temperature and the metal particle size. At room temperature, contact between the Co−Ni NPs and the reactants (ethanol and H 2 O) led to the formation of a Co−Ni oxide film over the Co−Ni metal core, with CoO/NiO = 1. For smaller Co−Ni NPs (about 5 nm), the oxide film showed a dynamic composition according to temperature, with Co migrating to the surface while being oxidized up to around 350 °C. A structure with a core of (Co,Ni) and a shell rich in CoO was formed, which could be reduced above 350 °C. The surface CoO was mainly reduced upon heating in the reaction stream, with migration into the NP cores. For larger Co−Ni NPs (about 10 nm), the oxide film remained stable up to 200 °C, being reduced by the ethanol stream at higher temperatures. At operating temperatures in the range of 350−400 °C, the surface structure of the Ni−Co alloy showed (Ni,Co)−O species, while these metal oxide species decreased with increases of the thermal treatment temperature and the nanoparticle size. At low temperatures, the Co−Ni nanoparticles were covered by CoO/NiO and were active for the oxidative dehydrogenation of ethanol. With the increase of temperature, surface CoO was reduced and incorporated in the Co−Ni nanoparticle core. These metal sites became active toward the reactant and catalyzed the dehydrogenation of ethanol, followed by C−C bond cleavage, resulting in the formation of CH 4 , CO, and H 2 . The presence of CoO at the surface of the smaller Co−Ni nanoparticles suppressed carbon accumulation, compared to larger Co−Ni or Ni nanoparticles that had highly reduced surfaces.

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Section: Resultsmentioning

confidence: 96%

Steam Reforming of Ethanol Using Ni–Co Catalysts Supported on MgAl₂O₄: Structural Study and Catalytic Properties at Different Temperatures

et al. 2021

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“…Compared to other techniques, such as chemical vapor deposition (CVD) [5], molecular beam epitaxy (MBE) [6], sol-gel synthesis [7] and pulsed laser deposition [8], ion implantation has several important advantages, including no synthesis-related impurities and precise control of the introduced metal ions and their depth distribution in the dielectric matrix [9]. Accordingly, nanoparticles of metals and metal oxides, such as copper (Cu) [10], gold (Au), nickel (Ni) [11], silver (Ag) [12], cobalt (Co) [13], etc., were synthesized by ion implantation in dielectrics such as SiO 2 [14], Al 2 O 3 [15], and even in MgO [16,17] or CeO 2 [13]. According to the literature sources, in the SiO 2 matrix, the implanted ions form spherical nanoparticles with a random distribution [14].…”

Section: Introductionmentioning

confidence: 99%

Influence of Annealing on the Dielectric Properties of Zn-SiO2/Si Nanocomposites Obtained in “Hot” Implantation Conditions

et al. 2022

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This paper presents the results of AC electrical measurements of Zn-SiO2/Si nanocomposites obtained by ion implantation. Implantation of Zn ions was carried out into thermally oxidized p-type silicon substrates with energy of 150 keV and fluence of 7.5 × 1016 ion·cm−2 at a temperature of 773 K, and is thus called implantation in “hot” conditions. The samples were annealed in ambient air for 60 min at 973 K. Electrical measurements of Zn-SiO2/Si nanocomposites were carried out before and after annealing. Measurements were performed in the temperature range from 20 K to 375 K. The measurement parameters were the resistance Rp, the capacitance Cp, the phase shift angle θ and the tangent of loss angle tanδ, as a function of the frequency in the range from 50 Hz to 5 MHz. Based on the characteristics σ(f) and the Jonscher power law before and after sample annealing, the values of the exponent s were calculated depending on the measurement temperature. Based on this, the conductivity models were matched. Additionally, the real and imaginary parts of the dielectric permittivity were determined, and on their basis, the polarization mechanisms in the tested material were also determined.

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Structure and magnetic properties of Fe nanoparticles in amorphous silica implanted with Fe ions and effect of subsequent energetic heavy ion irradiation

Iwase

Fukuda

Saitoh

et al. 2022

Journal of Applied Physics

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Amorphous silicon dioxide (hereafter SiO2) samples were implanted with 380 keV Fe ions at room temperature. After the implantation, some samples were irradiated with 16 MeV Au ions. The magnetic property was investigated by using a SQUID magnetometer, and the morphology of Fe-implanted SiO2 samples was examined by using a transmission electron microscope and x-ray absorption spectroscopy (extended x-ray absorption fine structure and x-ray absorption near edge structure). The size of Fe nanoparticles increases with an increase in the amount of Fe implantation. A part of Fe nanoparticles consists of Fe oxides, and with an increase in the amount of Fe implantation, the valence state of Fe atoms and the structure of Fe nanoparticles gets close to those of metallic α-Fe. The room temperature magnetism was observed in Fe-implanted SiO2 samples. The magnetization–magnetic field curves for samples implanted with a small amount of Fe are reproduced by the Langevin equation, implying that Fe nanoparticles present the superparamagnetic behavior. For a large amount of Fe implantation, the magnetization–magnetic field curve shows the ferromagnetic state. Such a result of magnetic property is consistent with the results of the x-ray absorption. By the subsequent 16 MeV Au irradiation, the Fe nanoparticles were fragmentated, resulting in the decrease in magnetization. The optical absorption property of the SiO2 samples is briefly discussed.

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Local structure study of the Ni nanoparticles embedded in SiO2 by ion implantation

Cited by 3 publications

References 13 publications

Steam Reforming of Ethanol Using Ni–Co Catalysts Supported on MgAl₂O₄: Structural Study and Catalytic Properties at Different Temperatures

Steam Reforming of Ethanol Using Ni–Co Catalysts Supported on MgAl₂O₄: Structural Study and Catalytic Properties at Different Temperatures

Influence of Annealing on the Dielectric Properties of Zn-SiO2/Si Nanocomposites Obtained in “Hot” Implantation Conditions

Structure and magnetic properties of Fe nanoparticles in amorphous silica implanted with Fe ions and effect of subsequent energetic heavy ion irradiation

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Local structure study of the Ni nanoparticles embedded in SiO2 by ion implantation

Cited by 3 publications

References 13 publications

Steam Reforming of Ethanol Using Ni–Co Catalysts Supported on MgAl2O4: Structural Study and Catalytic Properties at Different Temperatures

Steam Reforming of Ethanol Using Ni–Co Catalysts Supported on MgAl2O4: Structural Study and Catalytic Properties at Different Temperatures

Influence of Annealing on the Dielectric Properties of Zn-SiO2/Si Nanocomposites Obtained in “Hot” Implantation Conditions

Structure and magnetic properties of Fe nanoparticles in amorphous silica implanted with Fe ions and effect of subsequent energetic heavy ion irradiation

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Steam Reforming of Ethanol Using Ni–Co Catalysts Supported on MgAl₂O₄: Structural Study and Catalytic Properties at Different Temperatures

Steam Reforming of Ethanol Using Ni–Co Catalysts Supported on MgAl₂O₄: Structural Study and Catalytic Properties at Different Temperatures