Size and alloying induced shift in core and valence bands of Pd-Ag and Pd-Cu nanoparticles

Sengar, Saurabh K.; Mehta, B. R.; Govind,

doi:10.1063/1.4869437

Cited by 50 publications

(37 citation statements)

References 44 publications

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“…The NTs were found to exhibit hollow morphologies, which are desirable from the point‐of‐view of high specific surface areas. High‐resolution X‐ray photoelectron spectra (XPS) of the Pd x Ag NTs (Supporting Information, Figure S2) are consistent with alloying …”

Section: Figurementioning

confidence: 69%

Synergy between Plasmonic and Electrocatalytic Activation of Methanol Oxidation on Palladium–Silver Alloy Nanotubes

et al. 2019

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Localized surface plasmon resonance (LSPR) excitation of noble metal nanoparticles has been shown to accelerate and drive photochemical reactions. Here, LSPR excitation is shown to enhance the electrocatalysis of a fuel‐cell‐relevant reaction. The electrocatalyst consists of PdxAg alloy nanotubes (NTs), which combine the catalytic activity of Pd toward the methanol oxidation reaction (MOR) and the visible‐light plasmonic response of Ag. The alloy electrocatalyst exhibits enhanced MOR activity under LSPR excitation with significantly higher current densities and a shift to more positive potentials. The modulation of MOR activity is ascribed primarily to hot holes generated by LSPR excitation of the PdxAg NTs.

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Section: Figurementioning

confidence: 69%

Synergy between Plasmonic and Electrocatalytic Activation of Methanol Oxidation on Palladium–Silver Alloy Nanotubes

et al. 2019

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“…In the Cu 2p 3/2 spectrum, the main peak at ab inding energy (BE)o f9 30-935 eV was deconvolutedi nto two peaks that correspond to Cu 0 /Cu + + (BE = 931.9 eV) and Cu 2+ + (BE = 933.8 eV) species, respectively. [19,22] The satellite peak aroundB E = 941 eV was clear evidenceo f the existence of Cu 2+ + particlesi nt he Cu-Pd catalysts. As the binding energies of Cu 0 and Cu + + are very close, the Cu LMM spectrumw as recorded to distinguish these two species.…”

Section: Resultsmentioning

confidence: 97%

“…The Cu 2p 3/2 and Cu 2p 3/2 levels were fitted together with a fixed separation. In the Cu 2p 3/2 spectrum, the main peak at a binding energy (BE) of 930–935 eV was deconvoluted into two peaks that correspond to Cu 0 /Cu + (BE=931.9 eV) and Cu 2+ (BE=933.8 eV) species, respectively . The satellite peak around BE=941 eV was clear evidence of the existence of Cu 2+ particles in the Cu‐Pd catalysts.…”

Section: Resultsmentioning

confidence: 99%

Catalytic Transfer Hydrogenation of Furfural to 2‐Methylfuran and 2‐Methyltetrahydrofuran over Bimetallic Copper–Palladium Catalysts

et al. 2016

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The catalytic transfer hydrogenation of furfural to the fuel additives 2-methylfuran (2-MF) and 2-methyltetrahydrofuran (2-MTHF) was investigated over various bimetallic catalysts in the presence of the hydrogen donor 2-propanol. Of all the as-prepared catalysts, bimetallic Cu-Pd catalysts showed the highest catalytic activities towards the formation of 2-MF and 2-MTHF with a total yield of up to 83.9 % yield at 220 °C in 4 h. By modifying the Pd ratios in the Cu-Pd catalyst, 2-MF or 2-MTHF could be obtained selectively as the prevailing product. The other reaction conditions also had a great influence on the product distribution. Mechanistic studies by reaction monitoring and intermediate conversion revealed that the reaction proceeded mainly through the hydrogenation of furfural to furfuryl alcohol, which was followed by deoxygenation to 2-MF in parallel to deoxygenation/ring hydrogenation to 2-MTHF. Finally, the catalyst showed a high reactivity and stability in five catalyst recycling runs, which represents a significant step forward toward the catalytic transfer hydrogenation of furfural.

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“…It is believed that active oxygen can preferential adsorbs on the metals with the number of unpaired electrons, because each oxygen atom requires two unpaired electrons from the d-band for bond formation [13]. The interatomic electronic transfer may also be associated with so-called hybridization effect that involves an increased d to sp promotion of metals [40]. Thus, the increase unpaired electrons for Ag atoms donated form adjacent Pt atoms contributes to the formation of the partially filled bonding and antibonding states of Ag atoms [13], which result in the favorable adsorption of active oxygen on Ag atom surface, which would further facilitate the ORR kinetics on these Pt-Ag bimetallic catalysts.…”

Section: The Origin Of Improved Activity Of Pt-ag Bimetallic Catalystsmentioning

confidence: 99%

A novel strategy to synthesize bimetallic Pt–Ag particles with tunable nanostructures and their superior electrocatalytic activities toward the oxygen reduction reaction

et al. 2016

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The ability to precisely control the nanoscale phase structure of bimetallic catalysts is required to achieve a synergistic effect between two metal for oxygen reduction reaction (ORR). In this work, we synthesized Pt-Ag bimetallic nanoparticles (NPs) with Ag@Pt core-shell, highly alloyed solid and hollow nanostructures respectively, via a galvanic replacement reaction by modifying H 2 PtCl 6 concentration in an aqueous solution containing homemade Ag NPs as the sacrificial templates. The nanophase and corresponding electronic structures of the synthesized Pt-Ag NPs were characterized by transmission electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy. The formation of these Pt-Ag NPs with different 2 nanophase structures is closely ascribed to a defect-induced Kirkendall effect that involves the accelerated interdiffusion of Ag and Pt atoms, triggered by the high density of defects along the Ag NP surface generated by the galvanic replacement reaction. The nanophase structure-dependent electrocatalytic activity of three Pt-Ag bimetallic NPs was determined in 0.5 M H 2 SO 4 solution by using a rotating disk electrode (RDE). The results showed that the core-shell and hollow alloy NPs exhibit the excellent ORR activity in an acidic solution, which is remarkably higher than that of the commercial Pt/C (E-TEK). The physical origin of the enhancement in the ORR activity can be explained by a mutual ligand effect, raised by the substantial electronic transfer between Pt and Ag at the atomic level, which results from the downshift of the d-band center for Pt and the increased number of the unpaired electrons for Ag in these bimetallic catalysts. Thus two factors achieve a synergistic effect that dominates the remarkably improved electrocatalytic activity for the ORR.

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Size and alloying induced shift in core and valence bands of Pd-Ag and Pd-Cu nanoparticles

Cited by 50 publications

References 44 publications

Synergy between Plasmonic and Electrocatalytic Activation of Methanol Oxidation on Palladium–Silver Alloy Nanotubes

Synergy between Plasmonic and Electrocatalytic Activation of Methanol Oxidation on Palladium–Silver Alloy Nanotubes

Catalytic Transfer Hydrogenation of Furfural to 2‐Methylfuran and 2‐Methyltetrahydrofuran over Bimetallic Copper–Palladium Catalysts

A novel strategy to synthesize bimetallic Pt–Ag particles with tunable nanostructures and their superior electrocatalytic activities toward the oxygen reduction reaction

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