Support effect for nanosized Au catalysts in hydrogen production from formic acid decomposition

Zacharska, Monika; Chuvilin, Andrey; Kriventsov, V. V.; Beloshapkin, Sergey; Estrada, Miguel; Simakov, Andrey; Bulushev, Dmitri A.

doi:10.1039/c6cy00552g

Cited by 58 publications

(43 citation statements)

References 33 publications

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“…The spectra of Au 25 glass exhibited two peaks at 85.8 and 89.6 eV that are identified as being due to binding energies of Au 3+ ions . In addition, two weak peaks at 84.0 and 87.6 eV predicted as characteristic binding energies of 4f 7/2 and Au 4f 5/2 metallic Au species, are also located in the spectrum of Au 25 . Due to enhancing the concentration of Au 2 O 3 intensity of the peaks corresponding to metallic particles gradually dominated over that of Au 3+ peaks.…”

Section: Resultsmentioning

confidence: 90%

Structural and physical characteristics of Au₂O₃‐doped sodium antimonate glasses – Part I

et al. 2018

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Na2O‐Sb2O3 glasses doped with different concentrations of Au2O3 were prepared by melt quenching technique and later were heat treated at 800°C for 6 hours. Structural analysis by XRD, XPS, SEM, EDS, and DSC techniques indicated that the samples are embedded with multiple crystallites composed of Sb3+, Sb5+, Au3+ ions, and Au0 metallic particles. These studies have further demonstrated a gradual increasing fraction of Au0 metallic particles with increasing Au2O3 concentration. IR spectral studies suggested increasing the degree of polymerization of the glass network (due to increasing concentration of Sb5+ ions that participate in the glass network with SbVO4 structural units) with rise in the concentration of Au2O3. Optical absorption spectra of the titled samples have exhibited a broad absorption band at about 530 nm predicted due to the surface plasmon resonance (SPR) and exhibited a spectral red shift with increasing intensity with increase in Au2O3 content. Photoluminescence (PL) spectra of the samples recorded (at λexc = corresponding SPR band position) exhibited an emission peak at about 580 nm (identified as being due to interband transition between sp and d bands of gold particles). Overall, the analysis of these results has confirmed increasing concentration of Au metallic particles with increase in Au2O3 content in the titled material. Finally, it is predicted that the presence of higher concentration of gold particles in the polymerized antimonate glass network makes the materials useful for designing different nano dimensional optoelectronic devices.

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Section: Resultsmentioning

confidence: 90%

Structural and physical characteristics of Au₂O₃‐doped sodium antimonate glasses – Part I

et al. 2018

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“…FT‐EXAFS spectra show an obvious difference in the peak of shell at ≈1.7 Å, which corresponds to the AuO bonding distance . Such peak is rarely shown in Au foil or as‐0.83‐Au/mCo 3 O 4 , but clearly visible in AL‐0.83‐Au/mCo 3 O 4 , suggesting the significant increase of AuO bonding (i.e., increase of atomically dispersed/clustered Au species) in the leached catalyst . However, two peaks at ≈2.7 and ≈3.5 Å, originated from single Au–Au path contribution, were also observed .…”

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confidence: 96%

Controlled Leaching Derived Synthesis of Atomically Dispersed/Clustered Gold on Mesoporous Cobalt Oxide for Enhanced Oxygen Evolution Reaction Activity

et al. 2018

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The water splitting for hydrogen energy is largely constrained by sluggish anodic oxygen evolution reaction (OER). Cobalt oxide, one of the most promising non‐noble metal catalysts for OER, can exhibit highly enhanced catalytic OER activity when deposited on gold substrates. However, it still remains challenging to develop efficient Au/Co3O4 catalysts that can maximize the catalytic activity with the minimum use of gold. Here is reported a simple leaching derived synthesis of atomically dispersed/clustered gold on mesoporous cobalt oxides as highly efficient catalysts for OER. With greatly lowered gold contents <1 wt%, the catalyst shows twice as much current density and Au normalized activity than mesoporous cobalt oxide at 400 mV overpotential. The present work provides a simple synthesis route toward atomically dispersed/clustered gold supported catalysts, which can be extended to the development of a wide variety of efficient nanocatalysts that can be designed for specific applications.

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“…The spectra recorded in the low‐binding energy regions have exhibited two peaks (at 85.8 and 89.6 eV) related to the binding energies of Au 3+ ions. Two weak peaks at 84.0 and 87.6 eV corresponding to binding energies of 4f 7/2 and Au 4f 5/2 metallic Au spices are also visualized in these spectra. In Figures A,B, we have presented the XPS spectra for one of the samples viz, Au 100 in the low and high binding energy regions, respectively.…”

Section: Resultsmentioning

confidence: 85%

Structural and physical characteristics of Au₂O₃‐doped sodium antimonate glasses – Part II electrical characteristics

et al. 2018

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In continuation of our earlier investigations on structural and physical characteristics of Au2O3‐doped sodium antimonate glass‐ceramics (Part‐1), in this part we have investigated the influence of gold ions on electrical characteristics of the Na2O–Sb2O3: Au2O3 glass‐ceramics. The study contains the results of quantitate investigations on dielectric properties, impedance spectra and A.C. conductivity in larger ranges of continuous frequencies (4 Hz‐8 MHz) and temperatures (300‐630 K). The variations exhibited by dielectric parameters with temperature and also with frequency were discussed in terms of various polarization mechanisms. The observed dielectric relaxation effects were analyzed using pseudo Cole‐Cole plot method and the analysis indicated spreading of relaxation times for dipoles. A.c. conductivity and also d.c. conductivity were found to decrease (to three orders of magnitude) with increase in Au2O3 concentration upto 0.1 mol%. The decrement is ascribed to the increasing concentration of Sb5+ ions that were predicted to participate in the glass network forming with SbO4 units. Even though, both ionic and polaronic contributions are possible for conduction in the studied material, quantitative analysis of these results indicated that the polaronic conduction (due to intervalence transfer between Sb3+ ↔ Sb5+ and Au0 ↔ Au3+) is prevalent. The results have also suggested that there is a gradual decrement in the ionic component with increase in Au2O3 concentration. Variation in σac in the low‐temperature region could satisfactorily be explained using quantum mechanical tunneling (QMT) model. Analysis of the results of d.c. conductivity indicated that the small polaron hoping (SPH) model is valid, especially in a high‐temperature region while the low temperature part of d.c. conductivity is analyzed based on variable range hopping (VRH) model. Overall, the increase in Au2O3 dopant concentration in the studied glass‐ceramics caused a decrement in the magnitude of the conductivity or increase in the insulating strength of the material.

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Support effect for nanosized Au catalysts in hydrogen production from formic acid decomposition

Abstract: Au catalysts with the same particle sizes demonstrate the following order of activity in formic acid decomposition: Au/Al2O3 > Au/ZrO2 ∼ Au/CeO2 > Au/La2O3 > Au/MgO.

Cited by 58 publications

References 33 publications

Structural and physical characteristics of Au₂O₃‐doped sodium antimonate glasses – Part I

Structural and physical characteristics of Au₂O₃‐doped sodium antimonate glasses – Part I

Controlled Leaching Derived Synthesis of Atomically Dispersed/Clustered Gold on Mesoporous Cobalt Oxide for Enhanced Oxygen Evolution Reaction Activity

Structural and physical characteristics of Au₂O₃‐doped sodium antimonate glasses – Part II electrical characteristics

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Support effect for nanosized Au catalysts in hydrogen production from formic acid decomposition

Abstract: Au catalysts with the same particle sizes demonstrate the following order of activity in formic acid decomposition: Au/Al2O3 > Au/ZrO2 ∼ Au/CeO2 > Au/La2O3 > Au/MgO.

Cited by 58 publications

References 33 publications

Structural and physical characteristics of Au2O3‐doped sodium antimonate glasses – Part I

Structural and physical characteristics of Au2O3‐doped sodium antimonate glasses – Part I

Controlled Leaching Derived Synthesis of Atomically Dispersed/Clustered Gold on Mesoporous Cobalt Oxide for Enhanced Oxygen Evolution Reaction Activity

Structural and physical characteristics of Au2O3‐doped sodium antimonate glasses – Part II electrical characteristics

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Structural and physical characteristics of Au₂O₃‐doped sodium antimonate glasses – Part I

Structural and physical characteristics of Au₂O₃‐doped sodium antimonate glasses – Part I

Structural and physical characteristics of Au₂O₃‐doped sodium antimonate glasses – Part II electrical characteristics