Si Woo Lee

Gallium-containing alloys have recently been reported to hydrogenate CO₂ to methanol at ambient pressures. However, a full understanding of the Ga-promoted catalysts is still missing due to the lack of information about the surface structures formed under reaction conditions. Here, we employed near ambient pressure scanning tunneling microscopy and x-ray photoelectron spectroscopy to monitor the evolution of well-defined Cu-Ga surfaces during CO₂ hydrogenation. We show the

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 t

The intrinsic correlation between an enhancement of catalytic activity and the flow of hot electrons generated at metal-oxide interfaces suggests an intriguing way to control catalytic reactions and is a significant subject in heterogeneous catalysis. Here, we show surface plasmon-induced catalytic enhancement by the peculiar nanocatalyst design of hexoctahedral (HOH) Au nanocrystals (NCs) with Cu2O clusters. We found that this inverse catalyst comprising a reactive oxide for the catalytic porti

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 re

We report the effect of metal-oxide interfaces on CO oxidation catalytic activity with inverse TiO₂-nanostructured Au catalysts. The inverse nanocatalysts were prepared by depositing TiO₂via the liquid-phase immersion method on electrochemically synthesized Au nanostructure supports. The catalytic performance for CO oxidation was investigated using various amounts of Ti (i.e. 0.1-1.0 wt%) on two different morphologies of Au nanostructures (i.e. nanoporous and nanorod). In c

Fundamental understanding of energy dissipation on surfaces has been important issues for studying renewable energy conversion. An energetic electron with high kinetic energy can be produced by a non-adiabatic dissipation process when the surface is exposed to external energy, such as exothermic reaction, mechanical interaction, or photon absorption. Excited electrons with an energy of 1–3 eV that are not in thermal equilibrium in metal surfaces are called "hot electrons". Significantly, it has

Hot carriers generated from LSPR excitation of Au can transfer to Co₃O₄, thus enhancing the catalytic activity for CO oxidation.

Understanding the role of energy dissipation and charge transfer under exothermic chemical reactions on metal catalyst surfaces is important for elucidating the fundamental phenomena at solid-gas and solid-liquid interfaces. Recently, many surface chemistry studies have been conducted on the solid-liquid interface, so correlating electronic excitation in the liquid-phase with the reaction mechanism plays a crucial role in heterogeneous catalysis. In this review, we introduce the detection princi

Alloys of gallium with transition metals have recently received considerable attention for their applications in microelectronics and catalysis. Here, we investigated the initial stages of the Ga-Cu alloy formation on Cu(111) and Cu(001) surfaces using scanning tunneling microscopy (STM), X-ray photoelectron spectroscopy (XPS), and low energy electron diffraction (LEED). The results show that Ga atoms deposited using physical vapor deposition readily intermix with the Cu surface, leading to a ra

Excitation of hot electrons by energy dissipation under exothermic chemical reactions on metal catalyst surfaces occurs at both solid-gas and solid-liquid interfaces. Despite extensive studies, a comparative <i>operando</i> study directly comparing electronic excitation by electronically nonadiabatic interactions at solid-gas and solid-liquid interfaces has not been reported. Herein, on the basis of our <i>in situ</i> techniques for monitoring energy dissipation as a chemicurrent using a Pt/n-Si

Formulating a quantitative relationship between the extent of electron transfer at metal–oxide interfaces and catalytic performance aids the rational design of oxide-supported metal catalysts. An effective strategy for monitoring electron transfer at nanoscale interfacial sites is to detect in real time the hot electrons excited when catalytic reactions occur at metal–oxide perimeter sites. Here, based on our in situ techniques for extracting electron transfer as a current signal using a catalyt

Most compressive strengths commonly used in the construction field are in a range of 240 to 300 kgf/㎠ at 28 days. To get this rage of strengths, however, high-flowing concrete requires cementitious binders more than 400 to 450 kg/㎥ for preventing segregation and sedimentation of aggregates. This amount of cementitious binder generates a large emission of excessive hydration heat, which may consequently induce harmful cracks in concrete structure. In order to reduce excessive hydration heat, thus