Byungchan Han

Here, we present oxygen-deficient black ZrO2-x as a new material for sunlight absorption with a low band gap around ~1.5 eV, via a controlled magnesiothermic reduction in 5% H2/Ar from white ZrO2, a wide bandgap(~5 eV) semiconductor, usually not considered for solar light absorption. It shows for the first time a dramatic increase in solar light absorbance and significant activity for solar light-induced H2 production from methanol-water with excellent stability up to 30 days while white ZrO2 fa

Using first-principles density functional theory, we study the effect of particle size and surface structure on the chemisorption energy of OH and O on nanoparticles of Pt. We find that the chemisorption energies of O and OH are strongly affected by the size and structure of the Pt particle varying by up to $1.0\phantom{\rule{0.3em}{0ex}}\mathrm{eV}$ at different adsorption sites and particle sizes.

We argue that surface segregation can be substantially modified by the presence of adsorbates and present a first-principles method that allows us to equilibrate segregation and adsorption simultaneously on surfaces with fixed topology. The method is based on a cluster expansion theory to write the state of the system in terms of adsorbate and surface layer occupation variables. This model can be parametrized with density functional theory calculations and equilibrated at finite temperature with

The identification and development of efficient catalysts made of non-precious materials for oxygen reduction reaction (ORR) are essential for the successful operation of a wide range of energy devices. This study provides evidence that earth-abundant nanoparticles of transition metals encapsulated in a nitrogen-doped carbon shell (M@N–C, M=Fe, Co, Ni, Cu or Fe alloys) are promising catalysts in acidic solutions. By density functional theory calculations and experimental validations, we quantita

Cu is considered as the most promising catalyst for the electrochemical carbon dioxide reduction reaction (CO2RR) to produce C2+ hydrocarbons, but achieving high C2+ product selectivity and efficiency with long-term stability remains one of great challenges. Herein, we report a strategy to realize the CO2RR catalyst allowing high C2+ product selectivity and stable catalytic properties by utilizing the benefits of oxygen-plasma-assisted nitrogen doping on CuO. It is exhibited that the defects suc

This study establishes big data for the catalytic properties of two-dimensional metal-dichalcogenides (2D-TMDs) toward the hydrogen evolution reaction (HER). In addition to conventionally known active sites of edges, it proposes that terrace sites (or the basal plane) can be substantially activated for the HER.

Cu@N-C with the Cu particles encapsulated in N-doped carbon shells, which was activated by CO₂treatment, is an excellent electrocatalyst for the oxygen reduction reaction.

Using density functional theory (DFT) calculations, we identify the thermodynamically stable configurations of Pt-Co alloy nanoparticles of varying Co compositions and particle sizes. Our results indicate that the most thermodynamically stable structure is a shell-by-shell configuration where the Pt atom only shell and the Co only shell alternately stack and the outermost shell consists of a Pt skin layer. DFT calculations show that the structure has substantially higher dissolution potential of

The modulating of the geometric and electronic structures of metal-N-C atomic catalysts for improving their performance in catalyzing oxygen reduction reactions (ORRs) is highly desirable yet challenging. We herein report a delicate "encapsulation-substitution" strategy for the synthesis of paired metal sites in N-doped carbon. With the regulation of the <i>d</i>-orbital energy level, a significant increment in oxygen electroreduction activity was demonstrated in Ru-Co diatomic catalyst (DAC) co

N₄-chelate macrocycles comprise the foundation for non-precious metal oxygen reduction reaction (ORR) catalyst research, where the main electrochemical process occurs in polymer electrolyte membrane (PEM) fuel cells.

Nano-scale Pt particles are often reported to be more electrochemically active and stable in a fuel cell if properly displaced on support materials; however, the factors that affect their activity and stability are not well understood. We applied first-principles calculations and experimental measurements to well-defined model systems of N-doped graphene supports (N-GNS) to reveal the fundamental mechanisms that control the catalytic properties and structural integrity of nano-scale Pt particles