Experimental and computational studies of formic acid dehydrogenation over PdAu: influence of ensemble and ligand effects on catalysis

Lee, Jin Hee; Cho, Jinwon; Jeon, Mina; Ridwan, Muhammad; Park, Hyun S.; Choi, Sun Hee; Nam, Suk Woo; Han, Jonghee; Lim, Tae Hoon; Ham, Hyung Chul; Yoon, Chang Won

doi:10.1039/c6ta03654f

Cited by 41 publications

(34 citation statements)

References 43 publications

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“…155 Various palladium-based catalysts are also reported to accelerate the dehydrogenation pathway (Equation 24 where Pt is replaced by Pd) compared with the dehydration pathway (Equation 25 where Pt is replaced by Pd). [156][157][158][159][160][161][162] The composite catalysts of platinum black modified by a submonolayer of spontaneously deposited Ru (Pt/Ru) and platinum black modified by a submonolayer of spontaneously deposited Pd (Pt/Pd) showed a maximum OCV of 0.91 V and 0.59 V, respectively. 163 In contrast to OCV, the Pt/Ru catalyst gave the largest power of 70 mW cm À2 at low voltage of 0.26 V, whereas the Pt/ Pd gave the lower power of 41 mW cm À2 at 0.27 V. 163 The Pd-black-based DFAFC generated a maximum power density of 271 mW cm À1 at 30 C with a maximum OCV of 0.90 V. 164 The amount of Pd loading was reduced by preparing finely dispersed Pd particles deposited on carbon supports (Vulcan XC-72).…”

Section: Scheme 1 Catalytic Cycles Of Interconversion Between Hydrogmentioning

confidence: 99%

Production of Liquid Solar Fuels and Their Use in Fuel Cells

Fukuzumi

2017

Joule

173

116

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This review focuses on the production of liquid fuels using solar energy combined with their use in direct liquid fuel cells. The production of formic acid, which is the two-electron reduced product of CO 2 , as a solar liquid fuel as well as a hydrogen storage material is discussed together with its use in direct formate fuel cells. Other CO 2 reduction products such as methanol and formaldehyde as solar liquid fuels as well as hydrogen storage materials are reviewed with the performance of the corresponding fuel cells. The production of nitrogen fixation products such as ammonia and hydrazine is also reviewed together with their fuel cells. Finally, the production of hydrogen peroxide from not only pure water but also seawater and dioxygen in the air using solar energy is discussed and combined with the recent development of one-compartment hydrogen peroxide fuel cells.

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Section: Scheme 1 Catalytic Cycles Of Interconversion Between Hydrogmentioning

confidence: 99%

Production of Liquid Solar Fuels and Their Use in Fuel Cells

Fukuzumi

2017

Joule

173

116

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“…In addition, in some reactions such as alkane isomerization 6 , formaldehyde oxidation 7 , sub-nano clusters, which consist of several active atoms, are found to be more reactive than single-atom catalysts. 6,[8][9] Small nanoclusters are very attractive because of their specific structural and electronic properties, [10][11] which are important factors to understand their catalytic properties. However, an additional key characteristics of nanoclusters is the fluxionality, implying their ability to restructure in reaction conditions, and to access not one but an ensemble of low free energy structures.…”

Section: Introductionmentioning

confidence: 99%

Structural Rearrangements of Subnanometer Cu Oxide Clusters Govern Catalytic Oxidation

2020

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Sub-nanometer metal oxide clusters are very important materials, widely used for example in catalysis or electronic devices such as sensors. Hence, it is critical to understand the atomic structures and properties of subnanometer metal oxide clusters under a reactive gas environment, such as O 2. We consider here experimentally-accessible precise-size Cu clusters (Cu 4) supported on partial hydroxylated amorphous alumina and show that such clusters can access, in catalytic conditions at high temperature under a pressure of O 2 , a large ensemble of oxidized structures, representing a large variety of oxygen content, of geometries in link with the support, and of catalytic activities for oxidation reactions, as seen from their reducibilities. A 1 grand canonical basin hopping method based on first-principles energy, reveals an ensemble of 24 configurations for the Cu 4 O x cluster of low free energy, less than 0.8 eV above the global minimum. The low free energy ensemble consists of clusters of different stoichiometries, which are mainly Cu 4 O 3 and Cu 4 O 4 in the temperature range of 200−400 ℃ and under a pressure of 0.5 bar of O 2. The presence of several competitive isomers at each composition implies that cluster fluxionality impacts the phase diagram, which should be ensemble-averaged. In terms of catalytic oxidation activity, Cu 4 O 3 isomers present highly variable O abstraction energy: the most stable isomers are inactive for alkane oxidative dehydrogenation, but isomerization to metastable isomers, that proceed with low barrier, enable to create active configurations with low O abstraction energy. O atoms with lowest anionic character, and thus of more electrophilic nature, present the best oxidation capability. In contrast, all Cu 4 O 4 isomers show a low O abstraction energy and a high potential catalytic activity. This manuscript demonstrates the unique structural and electronic properties of sub-nano Cu oxides clusters and illustrates the critical roles of configuration ensembles and rearrangement to highly reactive metastable cluster isomers in nanocatalysis.

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“…The CO vibrational band at 2023 cm À 1 is assigned to the linear adsorption model of CO on atop Pd sites; while the peak at 2006 cm À 1 is identified as CO adsorbed on the bridge Pd sites. [34] Similar CO vibrational peaks over PdAu@mTiO 2 were observed but with lower frequencies. [35,36] For example, the bridged CO band on PdAu@mTiO 2 is centered at 1975 cm À 1 that is a 31 cm À 1 downshift in comparison with that of PdAu@mSiO 2 ; while, the linear CO adsorption appears at 2013 cm À 1 , corresponding to a roughly 10 cm À 1 downshift.…”

Section: Resultsmentioning

confidence: 55%

Polymer‐Assisted Co‐Assembly towards Synthesis of Mesoporous Titania Encapsulated Monodisperse PdAu for Highly Selective Hydrogenation of Phenylacetylene

Liu

et al. 2020

ChemCatChem

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Bimetallic nanoalloys have attracted great research interest in the past decades by virtue of their tunable metal‐metal synergies. The preparation of well‐defined bimetallic nanoalloys largely relies on the use of capping ligands, which brings a great challenge to utilize the surface‐accessible active sites and/or tailor bimetallic‐support interactions. In the current paper, surface‐clean, thermally stable and monodisperse PdAu nanoalloys confined in mesoporous TiO2 (PdAu@mTiO2) were prepared using evaporation‐induced self‐assembly with two colloidal templates. The hydrogenation activity of PdAu@mTiO2 was demonstrated to be approximately 6 times higher than that of PdAu nanoalloys supported on mesoporous silica due to the bimetallic‐support interactions. Our method is expected to open up new opportunities to synthesize ligand‐free and stable bimetallic nanoalloys with tailored bimetallic‐support interactions for highly efficient catalysis.

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Experimental and computational studies of formic acid dehydrogenation over PdAu: influence of ensemble and ligand effects on catalysis

Abstract: Au alloying into Pd can greatly improve the catalytic activity for FA dehydrogenation. Distinct PdAu surface ensembles are prepared and the Au alloying effects are revealed by experimental and theoretical examinations.

Cited by 41 publications

References 43 publications

Production of Liquid Solar Fuels and Their Use in Fuel Cells

Production of Liquid Solar Fuels and Their Use in Fuel Cells

Structural Rearrangements of Subnanometer Cu Oxide Clusters Govern Catalytic Oxidation

Polymer‐Assisted Co‐Assembly towards Synthesis of Mesoporous Titania Encapsulated Monodisperse PdAu for Highly Selective Hydrogenation of Phenylacetylene

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