Resolving ruthenium: XPS studies of common ruthenium materials

Morgan, David

doi:10.1002/sia.5852

Cited by 868 publications

(699 citation statements)

References 73 publications

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“…Also the XPS valence band hardly changes. Cl photoreduction has been reported before for RuCl 3 [25]. The Cl desorption will cause disorder at the surface which accounts for line broadening and loss of dispersion.…”

mentioning

confidence: 69%

JeffDescription of the Honeycomb Mott Insulatorα−RuCl3

Koitzsch¹,

Habenicht²,

Muller³

et al. 2016

Phys. Rev. Lett.

110

109

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Novel ground states might be realized in honeycomb lattices with strong spin-orbit coupling. Here we study the electronic structure of α-RuCl3, in which the Ru ions are in a d 5 configuration and form a honeycomb lattice, by angle-resolved photoemission, x-ray photoemission and electron energy loss spectroscopy supported by density functional theory and multiplet calculations. We find that α-RuCl3 is a Mott insulator with significant spin-orbit coupling, whose low energy electronic structure is naturally mapped onto J ef f states. This makes α-RuCl3 a promising candidate for the realization of Kitaev physics. Relevant electronic parameters such as the Hubbard energy U, the crystal field splitting 10Dq and the charge transfer energy ∆ are evaluated. Furthermore, we observe significant Cl photodesorption with time, which must be taken into account when interpreting photoemission and other surface sensitive experiments.

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mentioning

confidence: 69%

JeffDescription of the Honeycomb Mott Insulatorα−RuCl3

Koitzsch¹,

Habenicht²,

Muller³

et al. 2016

Phys. Rev. Lett.

110

109

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“…58 In the case of the Ru-HHDMA/TiSi 2 O 6 , a single Ru 3d 5/2 core level at 280.2 eV was displayed (Figure 6), confirming that the ruthenium surface is fully metallic. 58,59 An additional tool to further prove the oxidation state of the Ru catalysts is H 2 -TPR ( Figure S2). Apart from the decreased signal intensity observed at room temperature due to the stabilisation of the MS filament, Ru-HHDMA/TiSi 2 O 6 did not show any hydrogen consumption peak around 400 K, the expected temperature of reduction of RuO x species to Ru 0 .…”

Section: Resultsmentioning

confidence: 99%

Interfacial acidity in ligand-modified ruthenium nanoparticles boosts the hydrogenation of levulinic acid to gamma-valerolactone

Albani

Vilé

et al. 2017

Green Chem.

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a Gamma-valerolactone (GVL), a versatile renewable compound listed among the top 10 most promising platform chemical by the US Department of Energy, is produced via hydrogenation of levulinic acid (LA). The traditional high-loading ruthenium-on-carbon catalyst (5 wt.% Ru) employed for this transformation suffers from low metal utilisation and poor resistance to deactivation due to the formation of RuO x species. Aiming at an improved catalyst design, we have prepared ruthenium nanoparticles modified with the water-soluble hydroxyethyl-dimethyl ammonium dihydrogen phosphate (HHDMA) ligand and supported on TiSi 2 O 6 . The hybrid catalyst has been characterised by ICP-OES, elemental analysis, TGA, DRIFTS, H 2 -TPR, STEM, EDX, 31 P and 13 C MAS-NMR, and XPS. When evaluated in the continuous-flow hydrogenation of LA, the Ru-HHDMA/TiSi 2 O 6 catalyst (0.24 wt.% Ru) displays a fourfold higher reaction rate than the stateof-the-art Ru/C catalyst, while maintaining a 100% selectivity to GVL and no sign of deactivation after 15 hours on stream. An in-depth molecular analysis by Density Functional Theory demonstrates that the intrinsic acidic properties of the ligand-metal interface under reaction conditions ensure that the less energy demanding path is followed. The reaction does not obey the expected cascade mechanism and intercalates hydrogenation steps, hydroxyl/water eliminations, and ring closings to ensure high selectivity. Moreover, the interfacial acidity increases the robustness of the material against ruthenium oxide formation. These results provide valuable improvements for the sustainable production of GLV and insights for the rationalisation of the exceptional selectivity of Ru-based catalysts.

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“…S6, ESI †) indicates that the ruthenium species are RuO 2 . 53 Thus, 2.6 wt%RuO 2 nanoparticles have been loaded onto CTF-1-100W. According to the TEM image (as shown in Fig.…”

Section: Resultsmentioning

confidence: 99%

Efficient visible light-driven water oxidation and proton reduction by an ordered covalent triazine-based framework

Xie

Shevlin

Ruan

et al. 2018

Energy Environ. Sci.

251

188

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aWater oxidation is a rate-determining step in solar driven H 2 fuel synthesis and is technically challenging to promote. Despite decades of effort, only a few inorganic catalysts are effective and even fewer are effective under visible light. Recently, attention has been paid to synthetic semiconducting polymers, mainly on graphitic C 3 N 4 , with encouraging hydrogen evolution performance but lower activity for water oxidation. Here, a highly ordered covalent triazine-based framework, CTF-1 (C 8 N 2 H 4 ), is synthesised by a very mild microwave-assisted polymerisation approach. It demonstrates extremely high activity for oxygen evolution under visible light irradiation, leading to an apparent quantum efficiency (AQE) of nearly 4% at 420 nm. Furthermore, the polymer can also efficiently evolve H 2 from water. A high AQE of 6% at 420 nm for H 2 production has also been achieved. The polymer holds great potential for overall water splitting. This exceptional performance is attributed to its well-defined and ordered structure, low carbonisation, and superior band positions. Broader contextSplitting water by sunlight is an attractive renewable approach to generate clean hydrogen for producing chemicals or powering vehicles. This ultra-pure hydrogen also avoids the dreaded catalyst poisoning, which occurs even with very low levels of CO residuals from fossil-fuel generated hydrogen. The key challenge to sustain continued hydrogen generation from this artificial photosynthesis process is to speed up the water oxidation reaction, which is hard to proceed due to multiple electron transfer steps. Oxidation catalysts based on polymeric semiconductors are particularly promising for this purpose because of their abundance leading to low cost, tunable band structure to match the solar spectrum and variable degree of conjugation to impact on the p-p* excitation for efficient electron transfer. With a moderate microwave assisted strategy, we are able to control the degree of conjugation and minimise the undesirable structural carbonisation of a new type of polymeric photocatalyst-covalent triazine-based framework. The optimised catalyst shows advantageous band positions, to capture a wide spectrum of visible light and enhance the charge separation efficiency, leading to very high water oxidation and hydrogen evolution capabilities. The overall discovery paves the way for the development of efficient and continuous clean hydrogen production from the renewable visible-light water splitting process.

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Resolving ruthenium: XPS studies of common ruthenium materials

Cited by 868 publications

References 73 publications

JeffDescription of the Honeycomb Mott Insulatorα−RuCl3

JeffDescription of the Honeycomb Mott Insulatorα−RuCl3

Interfacial acidity in ligand-modified ruthenium nanoparticles boosts the hydrogenation of levulinic acid to gamma-valerolactone

Efficient visible light-driven water oxidation and proton reduction by an ordered covalent triazine-based framework

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