Hyun You Kim

Density functional theory was used to study the CO oxidation catalytic activity of CeO(2)-supported Au nanoparticles (NPs). Experimental observations on CeO(2) show that the surface of CeO(2) is enriched with oxygen vacancies. We compare CO oxidation by a Au(13) NP supported on stoichiometric CeO(2) (Au(13)@CeO(2)-STO) and partially reduced CeO(2) with three vacancies (Au(13)@CeO(2)-3VAC). The structure of the Au(13) NP was chosen to minimize structural rearrangement during CO oxidation. We sugg

Catalytic supremacy of Pt-single atoms achieved by CeO_x–TiO₂interfaces.

We scrutinized the reaction mechanism of CO2 methanation catalyzed by a Pd-MgO/SiO2 catalyst. Density functional theory studies showed that MgO and Pd nanoparticles play completely different roles. We found that MgO initiates the reaction by binding a CO2 molecule, forming a magnesium carbonate species on the surface, and that a supply of atomic H is essential for further hydrogenation of magnesium carbonate to methane. A CO2temperature-programmed desorption study gives credence to our findings

DFT+U calculations of CO oxidation by Au12 nanoclusters supported on a stepped-CeO2(111) surface show that lattice oxygen at the step edge oxidizes CO bound to Au NCs by the Mars-van Krevelen (M-vK) mechanism. We found that CO2 desorption determines the rate of CO oxidation, and the vacancy formation energy is a reactivity descriptor for CO oxidation. Our results suggest that the M-vK mechanism contributes significantly to CO oxidation activity at Au particles supported on the nano- or meso-stru

We used density functional theory to study CO oxidation catalyzed by TiO2(110), in which some Ti atoms on the surface are replaced with V, Cr, Mo, W, or Mn. We find that in the presence of O, V, Cr, Mo, and W dopants at the surface bind an oxygen atom so that the dopant has formula MO (M = V, Cr, Mo, W). Rutile doped with Mn does not take an oxygen atom from the gas phase. We find that these materials oxidize CO by a Mars−van Krevelen mechanism in which the role of the dopant is to facilitate th

DFT+U calculations of CO oxidation by Au13 nanoclusters (NCs) supported on either CeO2 or doped (X-Ce)O2 (X = Au, Pt, Pd, Ti, Ru, Zr) show that doping the CeO2 support accelerates CO oxidation by the Mars-van Krevelen mechanism at the Au-(X-Ce)O2 interface. We find that Au, Pd, Pt, and Ti dopants significantly lower the vacancy formation energy of the CeO2 support and that electron donation from the supported Au13 NC shifts the vacancy formation energy of (X-Ce)O2 and determines the final vacanc

We use density functional theory (DFT) to study CO-adsorption-induced Pd surface segregation in Au/Pd bimetallic surfaces, dynamics of Pd–Au swapping, effect of defects on the swapping rate, CO-induced Pd clustering, and the reaction mechanism of CO oxidation. The strong CO-philic nature of Pd atoms supplies a driving force for the preferential surface segregation of Pd atoms and Pd cluster formation. Surface vacancies are found to dramatically accelerate the rate of Pd–Au swapping. We find that

Abstract The development of highly active and durable Ir‐based electrocatalysts for the acidic oxygen evolution reaction (OER) is challenging because of the corrosive anodic conditions. Herein, IrO x /Zr 2 ON 2 electrocatalyst is demonstrated, employing Zr 2 ON 2 as a support material, to overcome the trade‐off between the activity and stability in the OER. Zr 2 ON 2 is selected due to its excellent electrical conductivity and chemical stability, and the fact that it induces strong interactions

Classical molecular dynamics simulations of the coalescence between an Ag cluster composed of 135 atoms and a Pd cluster of 16 atoms were performed at $500\phantom{\rule{0.3em}{0ex}}\mathrm{K}$. All Pd atoms penetrated into the Ag cluster and preferentially segregated at the subsurface layer. The density functional theory calculations revealed that the center site is the most stable position for Pd atoms. However, the energy barrier for further penetration of Pd atoms located at the subsurface w

The catalytic activity derived from the metal–support interaction at the Pt–CeO 2 interface can be demonstrated by the two descriptors of Pt particle size and CeO 2 morphology.

Platinum-based heterogeneous catalysts are mostly used in various commercial chemical processes because of their high catalytic activity, influenced by the metal/oxide interaction. To design rational catalysts with high performance, it is crucial to understand the relationship between the metal-oxide interface and the reaction pathway. Here, we investigate the role of oxygen defect sites in the reaction mechanism for CO oxidation using Pt nanoparticles supported on mesoporous TiO₂ cat

Achieving high mobility and reliability in atomic layer deposition (ALD)-based IGZO thin-film transistors (TFTs) with an amorphous phase is vital for practical applications in relevant fields. Here, we suggest a method to effectively increase stability while maintaining high mobility by employing the selective application of nitrous oxide plasma reactant during plasma-enhanced ALD (PEALD) at 200 °C process temperature. The nitrogen-doping mechanism is highly dependent on the intrinsic carbon imp

In this study, we report a facile synthetic pathway to three-dimensional (3D) Pd nanosponge-shaped networks wrapped by graphene dots (Pd@G-NSs), which show superior electrocatalytic activity toward the hydrogen evolution reaction (HER) and exhibited excellent long-term stability in acidic media. Pd@G-NSs were synthesized by simply mixing Pd precursors, reducing agent, carbon dots (Cdots), and Br^- ion at 30 °C. Experimental results and density functional theory (DFT) calculations sugge