Enhanced hot electron generation by inverse metal–oxide interfaces on catalytic nanodiode

Lee, Hyosun; Yoon, Sinmyung; Jo, Jinwoung; Jeon, Beomjoon; Hyeon, Taeghwan; An, Kwangjin; Park, Jeong Young

doi:10.1039/c8fd00136g

Cited by 13 publications

(16 citation statements)

References 35 publications

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“…Furthermore, for understanding hot electron dynamics at inverse oxide/metal interfacial sites, Lee et al fabricated a Schottky nanodevice by depositing Co 3 O 4 nanoparticles on a Pt film/TiO 2 nanodiode forming nanoscale inverse oxide−metal interfaces (Figure 13e). 192 Similar to the previous study, both the chemicurrent and catalytic activity were enhanced at the inverse CoO−Pt interfaces under the H 2 oxidation reaction. To demonstrate the electronic features on the inverse oxide/metal interface, the chemicurrent yield was estimated both on Pt/TiO 2 nanodiode and Co 3 O 4 nanoparticles/Pt/TiO 2 nanodiode, as shown in Figure 13f.…”

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confidence: 85%

“…Therefore, on the basis of both the turnover rate and chemicurrent results, we can conclude that the synergistic catalytic activity of the bimetallic Pt–Co nanoparticles came from the formation of the CoO–Pt interface under surface chemical reaction environments. Furthermore, for understanding hot electron dynamics at inverse oxide/metal interfacial sites, Lee et al fabricated a Schottky nanodevice by depositing Co 3 O 4 nanoparticles on a Pt film/TiO 2 nanodiode forming nanoscale inverse oxide–metal interfaces (Figure e) . Similar to the previous study, both the chemicurrent and catalytic activity were enhanced at the inverse CoO–Pt interfaces under the H 2 oxidation reaction.…”

Section: Operando Surface Science On Nanoparticle Catalystmentioning

confidence: 67%

“…The rectifying junction can form at the interface between the Pt film and TiO 2 . (f) Chemicurrent yield from the Pt film/TiO 2 and Co 3 O 4 nanoparticles/Pt film/TiO 2 nanodiodes under the H 2 oxidation reaction 192.…”

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confidence: 99%

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Operando Surface Characterization on Catalytic and Energy Materials from Single Crystals to Nanoparticles

Choi

Kim

et al. 2020

ACS Nano

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Modern surface science faces two major challenges, a materials gap and a pressure gap. While studies on single crystal surface in ultrahigh vacuum have uncovered the atomic and electronic structures of the surface, the materials and environmental conditions of commercial catalysis are much more complicated, both in the structure of the materials and in the accessible pressure range of analysis instruments. Model systems and operando surface techniques have been developed to bridge these gaps. In this Review, we highlight the current trends in the development of the surface characterization techniques and methodologies in more realistic environments, with emphasis on recent research efforts at the Korea Advanced Institute of Science and Technology. We show principles and applications of the microscopic and spectroscopic surface techniques at ambient pressure that were used for the characterization of atomic structure, electronic structure, charge transport, and the mechanical properties of catalytic and energy materials. Ambient pressure scanning tunneling microscopy and X-ray photoelectron spectroscopy allow us to observe the surface restructuring that occurs during oxidation, reduction, and catalytic processes. In addition, we introduce the ambient pressure atomic force microscopy that revealed the morphological, mechanical, and charge transport properties that occur during the catalytic and energy conversion processes. Hot electron detection enables the monitoring of catalytic reactions and electronic excitations on the surface. Overall, the information on the nature of catalytic reactions obtained with operando spectroscopic and microscopic techniques may bring breakthroughs in some of the global energy and environmental problems the world is facing.

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confidence: 85%

Section: Operando Surface Science On Nanoparticle Catalystmentioning

confidence: 67%

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Operando Surface Characterization on Catalytic and Energy Materials from Single Crystals to Nanoparticles

Choi

Kim

et al. 2020

ACS Nano

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“…We note that in our previous research, we found that hot electrons are generated much more in the reaction to methyl formate than CO 2 30 and it can be concluded that enhanced hot electron excitation obtained on Pt nanowires/TiO 2 indeed originates from their improved selectivity on nanoscale Pt-TiO 2 interfacial sites. Recently, we fabricated a Schottky nanodiode that formed a Pt/CoO interface and reported a significant increase in catalytic activity and hot electron excitation by hydrogen oxidation 48,49 . Thus, the improved partial oxidation selectivity when Pt nanowires were supported on TiO 2 can be attributed to the Pt-TiO 2 interfacial sites formed in the nanodiode, and owing to this increased selectivity, the efficiency of hot electron excitation was enhanced.…”

Section: Detection Of Hot Electrons On Pt Nanowires/tio 2 Nanodiodesmentioning

confidence: 99%

Controlling hot electron flux and catalytic selectivity with nanoscale metal-oxide interfaces

et al. 2021

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Interaction between metal and oxides is an important molecular-level factor that influences the selectivity of a desirable reaction. Therefore, designing a heterogeneous catalyst where metal-oxide interfaces are well-formed is important for understanding selectivity and surface electronic excitation at the interface. Here, we utilized a nanoscale catalytic Schottky diode from Pt nanowire arrays on TiO2 that forms a nanoscale Pt-TiO2 interface to determine the influence of the metal-oxide interface on catalytic selectivity, thereby affecting hot electron excitation; this demonstrated the real-time detection of hot electron flow generated under an exothermic methanol oxidation reaction. The selectivity to methyl formate and hot electron generation was obtained on nanoscale Pt nanowires/TiO2, which exhibited ~2 times higher partial oxidation selectivity and ~3 times higher chemicurrent yield compared to a diode based on Pt film. By utilizing various Pt/TiO2 nanostructures, we found that the ratio of interface to metal sites significantly affects the selectivity, thereby enhancing chemicurrent yield in methanol oxidation. Density function theory (DFT) calculations show that formation of the Pt-TiO2 interface showed that selectivity to methyl formate formation was much larger in Pt nanowire arrays than in Pt films because of the different reaction mechanism.

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“…Density functional theory (DFT) calculations confirmed that the step exhibiting the highest exothermic energy was in the methyl formate reaction, thus proving the facilitation of hot electron generation in the partial oxidation reaction. Recently, we reported some studies that detect hot electrons produced by the hydrogen oxidation reaction where only one product is produced (i.e., hydrogen oxidation only forming water as the product), ,, which showed a correlation between the catalytic activity and hot electron flux. In this work, we used a reaction where multiple products are produced (i.e., methanol oxidation forming CO 2 and methyl formate) so we can observe the selectivity and hot electron flux.…”

Section: Introductionmentioning

confidence: 99%

Intrinsic Relation between Hot Electron Flux and Catalytic Selectivity during Methanol Oxidation

et al. 2019

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Catalytic selectivity, or the production of only one desired molecule that may be used as a fuel or chemical out of several thermodynamically possible molecules, is the foundation of surface chemistry. During catalytic reactions, electronic excitation taking place on the surface creates energetic electrons called “hot electrons” that have a significant impact on catalytic reactions. Despite its importance in fundamentally understanding electronic excitation on the surface, no reports show the relation between hot electron flow and catalytic selectivity. Here, using a Pt/n-type TiO2 Schottky nanodiode, we show the intrinsic relation between hot electron flow and catalytic selectivity. On the Pt thin film, hot electron flow was generated by methanol oxidation exhibiting a two-path reaction of either full oxidation to CO2 or partial oxidation to methyl formate; a steady-state chemicurrent was detected. We show that the activation energy of the chemicurrent is quite close to that of the turnover frequency, indicating that the chemicurrent originated from the catalytic reaction on the Pt thin film. The dependence of the chemicurrent on methanol partial pressure was investigated by varying the partial pressure of methanol (1–4 Torr). We show that hot electron generation is more effective in the reaction pathway that produces methyl formate. On the basis of these results, we conclude that the selectivity for methyl formate production correlates well with hot electron generation because of the higher exothermicity of generating the intermediate, as was confirmed using theoretical calculations based on the density functional theory.

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Enhanced hot electron generation by inverse metal–oxide interfaces on catalytic nanodiode

Abstract: Mechanistic understanding of hot electron dynamics at inverse oxide/metal interfaces from a new catalytic nanodiode that exhibits nanoscale metal–oxide interfaces.

Cited by 13 publications

References 35 publications

Operando Surface Characterization on Catalytic and Energy Materials from Single Crystals to Nanoparticles

Operando Surface Characterization on Catalytic and Energy Materials from Single Crystals to Nanoparticles

Controlling hot electron flux and catalytic selectivity with nanoscale metal-oxide interfaces

Intrinsic Relation between Hot Electron Flux and Catalytic Selectivity during Methanol Oxidation

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