Hydrogen Oxidation-Driven Hot Electron Flow Detected by Catalytic Nanodiodes

Hervier, Antoine; Renzas, Russ; Park, Jeong Young; Somorjai, Gábor A.

doi:10.1021/nl9023275

Cited by 100 publications

(107 citation statements)

References 40 publications

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“…Furfuraldehyde binding on the [101] surface of anatase TiO 2 is discussed here; binding on other low-energy surfaces was considered with similar conclusions. When there is no O-vacancy on the surface, the calculations show that the furfuraldehyde molecule does not bind with either Ti cations or O anions on the surface.…”

Section: Charge Transfer From Tio 2 To Furfuraldehydementioning

confidence: 90%

“…99 Acid catalysis represents a unique chemistry that relies on charge transfer via protons and molecular ions, and many similarities appear to exist between SMSI and acid-base catalysis. The evolution of this work that began by measuring chemically induced charge flow at the oxide-metal interface [100][101][102] is quickly leading to a molecular level study of acid catalyzed chemistry with a focus on understanding the close relationship between charge flow and catalytic selectivity. Specifically, it is clear that a fundamental understanding of catalyst selectivity is closely related to understanding the flow of charge between various active sites on a catalyst.…”

Section: Methodsmentioning

confidence: 99%

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Charge Transfer and Catalysis at the Metal Support Interface

Baker

2012

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Kinetic, electronic, and spectroscopic characterization of model Pt-support systems are used to demonstrate the relationship between charge transfer and catalytic activity and selectivity. The results show that charge flow controls the activity and selectivity of supported metal catalysts.Using a Pt/n-Si Schottky junction, it is possible to externally control the electronic properties at the Pt/Si interface by applying bias or by exciting charge carriers with visible light. It is found that this device can control the rate of CO oxidation on Pt. Results show that negative charge on the Pt increases the reaction rate while positive charge on the Pt decreases the reaction rate. This is the first time that a solid-state device has been used to externally control the rate of a chemical reaction as determined by directly measuring the product yield. Similar experiments were performed for the H 2 oxidation reaction and analogous results were obtained.Similarly, electronic control of catalyst performance can be achieved by substrate doping. It is shown that F doping can tune the electronic structure of TiO 2 . When F is incorporated into TiO 2 , the electrical conductivity is dramatically enhanced because F acts as an n-type dopant. It is shown that this highly n-type TiO 2 acts as an electronically active support for Pt catalysts, increasing the rate of CO oxidation by electronically activating surface O. It is further shown that for a multipath reaction, the electronic structure of TiO 2 also controls the reaction selectivity. The electronic activity of highly n-type TiO 2 serving as a Pt support for methanol oxidation selectively enhances the production of formaldehyde relative to CO 2 .Finally, sum frequency generation (SFG) vibrational spectroscopy is used to probe the molecular nature of strong metal-support interactions (SMSI). This is the first time that SFG has been used to probe the highly selective oxide-metal interface during catalytic reaction, and the results demonstrate that charge transfer from TiO 2 on a Pt/TiO 2 catalyst controls the product distribution of furfuraldehyde hydrogenation by an acid-base mechanism. SFG spectra reveal that a furfuryl-oxy intermediate forms on TiO 2 as a result of a charge transfer interaction. This furfuryl-oxy intermediate is a highly active and selective precursor to furfuryl alcohol, and spectral analysis shows that the Pt/TiO 2 interface is required primarily for H spillover. Density functional calculations predict that O-vacancies on the TiO 2 surface activate the formation of the furfuryl-oxy intermediate via an electron transfer to furfuraldehyde, drawing a strong analogy between SMSI and acid-base catalysis. 2This dissertation builds on extensive existing knowledge of metal-support interactions in heterogeneous catalysis. The results show the prominent role of charge transfer at catalytic interfaces to determine catalytic activity and selectivity. Further, this research demonstrates the possibility of selectively driving catalytic chemistry by controlling charge f...

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Section: Charge Transfer From Tio 2 To Furfuraldehydementioning

confidence: 90%

Section: Methodsmentioning

confidence: 99%

Charge Transfer and Catalysis at the Metal Support Interface

Baker

2012

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“…5A. One can detect a so-called chemicurrent, which is correlated with the turnover rate of exothermic CO oxidation or hydrogen oxidation reactions (58). Theoretical calculations showed that the transition state in these processes involves CO 2 − or H 2 O − , which yields the chemicurrent that is proportional to the turnover rate.…”

Section: Oxide-metal Interfaces As Active Sites For Acid-base Catalysismentioning

confidence: 99%

Molecular catalysis science: Perspective on unifying the fields of catalysis

Hurlburt

Sabyrov

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

Self Cite

100

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Colloidal chemistry is used to control the size, shape, morphology, and composition of metal nanoparticles. Model catalysts as such are applied to catalytic transformations in the three types of catalysts: heterogeneous, homogeneous, and enzymatic. Real-time dynamics of oxidation state, coordination, and bonding of nanoparticle catalysts are put under the microscope using surface techniques such as sumfrequency generation vibrational spectroscopy and ambient pressure X-ray photoelectron spectroscopy under catalytically relevant conditions. It was demonstrated that catalytic behavior and trends are strongly tied to oxidation state, the coordination number and crystallographic orientation of metal sites, and bonding and orientation of surface adsorbates. It was also found that catalytic performance can be tuned by carefully designing and fabricating catalysts from the bottom up. Homogeneous and heterogeneous catalysts, and likely enzymes, behave similarly at the molecular level. Unifying the fields of catalysis is the key to achieving the goal of 100% selectivity in catalysis.Two major breakthroughs have revolutionized molecular catalysis science over the last 20 y. The first is in the development of nanomaterials science (1-4), which has made it possible to synthesize metallic (5-7), bimetallic, and core-shell nanoparticles (8, 9), mesoporous metal oxides (10, 11), and enzymes (12-16) in the nanocatalytic range between 0.8 and 10 nm. The second innovation is in the advancement of spectroscopy and microscopy instruments (17-20)-including nonlinear laser optics (21), sum-frequency generation vibrational spectroscopy (22-24), and synchrotronbased instruments, such as ambient pressure X-ray photoelectron spectroscopy (8,(25)(26)(27), X-ray absorption near-edge structure, extended X-ray absorption fine structure (28-30), infrared (IR) and X-ray microspectroscopies (31), and high-pressure scanning tunneling microscopies (32, 33)-that characterize catalysts at the atomic and molecular levels under reaction conditions (34). Most of the studies that use these techniques focus on nanoscale technologies, such as catalytic energy conversion and information storage, which have reduced the size of transistors to below 25 nm (35).Catalysts are classified into three types-heterogeneous, homogeneous, and enzymatic-and, in most cases, range in size from 1 to 10 nm, which is even smaller than the transistors being developed by the latest size-fabrication technologies. Heterogeneous catalysts work in reaction systems with multiple phases (e.g., solid-gas or solid-liquid phase); homogeneous catalysts reside in the same phase as the reactants, almost always in the liquid phase; and enzymatic catalysts, which are most active in an aqueous solution, make use of active sites in proteins. The catalysis of chemical energy conversion provides ever-increasing selectivity in producing combustible hydrocarbons, gasoline, and diesel.The tenets that direct our catalysis research involve nanoparticle synthesis, characterization under reaction con...

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“…This generates a hot electron, which, if the distance of travel to a Schottky interface is less than the mean free path of the electron, can cross the barrier and end up in the conduction band of the oxide (allowing a current to be measured). This has been done with both Pt films [84][85][86][87][88] and colloidal Pt nanoparticles on a Au/TiO 2 nanodiode, [89,90] the latter is depicted in Figure 6. higher potential than in Au, causing current to flow so a "chemicurrent" can be measured…”

Section: The Oxide Metal Interfacementioning

confidence: 99%

Conquering Catalyst Complexity: Nanoparticle Synthesis and Instrument Development for Molecular and Atomistic Characterisation Under In Situ Conditions

Somorjai

Beaumont

2015

Top Catal

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. (2015) 'Conquering catalyst complexity : nanoparticle synthesis and instrument development for molecular and atomistic characterisation under in situ conditions.', Topics in catalysis., 58 (10). pp. 560-572. Further information on publisher's website:http://dx.doi.org/10.1007/s11244-015- Publisher's copyright statement:The nal publication is available at Springer via http://dx.doi.org/10.1007/s11244-015-0398-5Additional information: Use policyThe full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-prot purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details. resolution in situ techniques with atomically and molecularly well-defined nanoparticle catalysts to achieve this goal. In particular we focus on mono-dispersed metal nanoparticles in the 0.8 -10 nm range with precise size distribution provided by modern colloidal synthetic techniques. These have been used in conjunction with a range of in situ techniques for understanding the complexity of a number of catalytic phenomena. Drawing on the nanoparticle size discrimination afforded by this approach, most metal nanoparticle catalysed covalent bond making/breaking reactions are identified as being structure sensitive, even when that was previously not thought to be the case. Small nanoparticles, below 2 nm, have been found to have changes of electronic structure that give rise to high oxidation state clusters under reaction conditions. These have been utilized to heterogenize typically homogeneous catalytic reactions using metal nanoclusters in the range of 40 atoms or less to carry out reactions on their heterogenized surfaces that would typically be expected only to occur at the higher oxidation state metal centre of a homogeneous organometallic catalyst. The combination of in-situ techniques and highly controlled metal nanoparticle structure also allows valuable insights to be achieved in understanding the mechanisms of multicomponent catalysts, catalysis occurring in different fluid phases and phenomena occurring at the metal-oxide interface.

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Hydrogen Oxidation-Driven Hot Electron Flow Detected by Catalytic Nanodiodes

Cited by 100 publications

References 40 publications

Charge Transfer and Catalysis at the Metal Support Interface

Charge Transfer and Catalysis at the Metal Support Interface

Molecular catalysis science: Perspective on unifying the fields of catalysis

Conquering Catalyst Complexity: Nanoparticle Synthesis and Instrument Development for Molecular and Atomistic Characterisation Under In Situ Conditions

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