Jeong Young Park

ADVERTISEMENT RETURN TO ISSUEReviewNEXTRole of Hot Electrons and Metal–Oxide Interfaces in Surface Chemistry and Catalytic ReactionsJeong Young Park*†‡, L. Robert Baker§, and Gabor A. Somorjai*∥⊥View Author Information† Center for Nanomaterials and Chemical Reactions, Institute for Basic Science, Daejeon 305-701, South Korea‡ Graduate School of EEWS, KAIST, Daejeon 305-701, South Korea§ Department of Chemistry and Biochemistry, The Ohio State University, Columbus, Ohio 43210, United States∥ Depa

Graphene produced by exfoliation has not been able to provide an ideal graphene with performance comparable to that predicted by theory, and structural and/or electronic defects have been proposed as one cause of reduced performance. We report the observation of domains on exfoliated monolayer graphene that differ by their friction characteristics, as measured by friction force microscopy. Angle-dependent scanning revealed friction anisotropy with a periodicity of 180° on each friction domain. T

ADVERTISEMENT RETURN TO ISSUEPREVReviewNEXTFundamental Aspects of Energy Dissipation in FrictionJeong Young Park*†‡ and Miquel Salmeron*§∥View Author Information† Center for Nanomaterials and Chemical Reactions, Institute for Basic Science, Daejeon 305-701, Republic of Korea‡ Graduate School of EEWS, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 305-701, Republic of Korea§ Materials Sciences Division, Lawrence Berkeley National Laboratory, University of California—Berkeley,

Recent breakthroughs in synthesis in nanoscience have achieved control of size and composition of nanoparticles that are relevant for catalyst design. Here, we show that the catalytic activity of CO oxidation by Rh/Pt bimetallic nanoparticles can be changed by varying the composition at a constant size (9+/-1 nm). Two-dimensional Rh/Pt bimetallic nanoparticle arrays were formed on a silicon surface via the Langmuir-Blodgett technique. Composition analysis with X-ray photoelectron spectroscopy ag

A remarkable dependence of the friction force on carrier concentration was found on doped silicon substrates. The sample was a nearly intrinsic n-type Si(100) wafer patterned with 2-micrometer-wide stripes of highly B-doped p-type material. The counter surface was the tip of an atomic force microscope coated with conductive titanium nitride. The local carrier concentration was controlled through application of forward or reverse bias voltages between the tip and the sample in the p and the n reg

Strong friction anisotropy is found when the twofold surface of an atomically clean aluminum-nickel-cobalt quasicrystal slides against a thiol-passivated titanium-nitride tip. Friction along the aperiodic direction is one-eighth as much as that along the periodic direction. This anisotropy, which is about three times as large as the highest value observed in anisotropic crystalline surfaces, disappears after the surface is oxidized in air. These results reveal a strong connection between interfa

Hot electron flow generated on colloid platinum nanoparticles during exothermic catalytic carbon monoxide oxidation was directly detected with Au/TiO2 diodes. Although Au/TiO2 diodes are not catalytically active, platinum nanoparticles on Au/TiO2 exhibit both chemicurrent and catalytic turnover rate. Hot electrons are generated on the surface of the metal nanoparticles and go over the Schottky energy barrier between Au and TiO2. The continuous Au layer ensures that the metal nanoparticles are el

Energy dissipation at surfaces and interfaces is mediated by excitation of elementary processes, including phonons and electronic excitation, once external energy is deposited to the surface during exothermic chemical processes. Nonadiabatic electronic excitation in exothermic catalytic reactions results in the flow of energetic electrons with an energy of 1-3 eV when chemical energy is converted to electron flow on a short (femtosecond) time scale before atomic vibration adiabatically dissipate

The origin of the synergistic catalytic effect between metal catalysts and reducible oxides has been debated for decades. Clarification of this effect, namely, the strong metal-support interaction (SMSI), requires an understanding of the geometric and electronic structures of metal-metal oxide interfaces under operando conditions. We show that the inherent lattice mismatch of bimetallic materials selectively creates surface segregation of subsurface metal atoms. Interfacial metal-metal oxide nan

While hot carrier generation from surface plasmon decay at the surface of a nanostructured metal offers a distinctive concept for boosting photoelectrocatalytic reactions, the nature of the plasmonic hot hole transfer based on the sizes of metallic nanomaterials has not been investigated in depth experimentally. Here, we report direct photoelectrochemical (PEC) experimental proof that the injection of plasmonic hot holes depends on the size of the metallic nanostructures. PEC results clearly ind

Continuous flow of ballistic charge carriers is generated by an exothermic chemical reaction and detected using the catalytic metal-semiconductor Schottky diode. We obtained a hot electron current for several hours using two types of catalytic nanodiodes, Pt/TiO2 or Pt/GaN, during carbon monoxide oxidation at pressures of 100 Torr of O2 and 40 Torr of CO at 413-573 K. This result reveals that the chemical energy of an exothermic catalytic reaction is directly converted into hot electrons flux in

The influence of physical and chemical properties of Pt/TiO2, Pd/TiO2, and Pt/GaN metal−semiconductor Schottky diodes on the yield of collected hot electron flow (number of hot electrons per product molecule) was investigated. We measured both the chemicurrent (electron flow) and chemical turnover rate during oxidation of carbon monoxide (at pressures of 100 Torr of O2 and 40 Torr of CO in the 373−513 K range) using reaction systems equipped for simultaneous reaction rate and current measurement

The use of hot carriers generated from the decay of localized surface plasmon resonance in noble metal nanoparticles is a promising concept for photocatalysis. Here, we report the enhancement of photocatalytic activity by the flow of hot electrons on TiO₂ nanotube arrays decorated with 5-30 nm Au nanoparticles as photoanodes for photoelectrochemical water splitting. This enhanced photocatalytic activity is correlated to the size of the Au nanoparticles, where higher oxygen evolution w