Hyunjoo Lee

As a catalyst, single-atom platinum may provide an ideal structure for platinum minimization. Herein, a single-atom catalyst of platinum supported on titanium nitride nanoparticles were successfully prepared with the aid of chlorine ligands. Unlike platinum nanoparticles, the single-atom active sites predominantly produced hydrogen peroxide in the electrochemical oxygen reduction with the highest mass activity reported so far. The electrocatalytic oxidation of small organic molecules, such as fo

Activity revived: Platinum nanoparticles (cuboctahedra, cubes, and porous particles, see picture, from left to right) capped with alkylammonium ions are synthesized by manipulating the reduction kinetics. The catalytic activity of these nanoparticles is superior to that of nanoparticles whose shape was controlled with a polymeric capping agent and foreign metal ions. Supporting information for this article is available on the WWW under http://www.wiley-vch.de/contents/jc_2002/2006/z603068_s.pdf

Arsenite [As(III)] and arsenate [As(V)] are highly toxic aquatic contaminants. Since arsenite is more mobile in natural waters and less efficiently removed in adsorption/coagulation processes than arsenate, the oxidation of arsenite to arsenate is desirable in water treatment. We performed the photocatalytic oxidation of arsenite in aqueous TiO2 suspension and investigated the effects of pH, dissolved oxygen, humic acid (HA), and ferric ions on the kinetics and mechanisms of arsenite oxidation.

Abstract Electrochemical water splitting is promising for utilizing intermittent renewable energy. The sluggish kinetics of the oxygen evolution reaction (OER), however, is a bottleneck in obtaining high efficiency. Only a few OER electrocatalysts have been developed for the use in acidic media despite the importance of a proton exchange membrane (PEM) water electrolyzer. IrO 2 is the only material that is both active and stable for the OER in highly corrosive acidic conditions. Herein, a facile

Single-atom catalysts (SACs), in which metal atoms are dispersed on the support without forming nanoparticles, have been used for various heterogeneous reactions and most recently for electrochemical reactions. In this Minireview, recent examples of single-atom electrocatalysts used for the oxygen reduction reaction (ORR), hydrogen oxidation reaction (HOR), hydrogen evolution reaction (HER), formic acid oxidation reaction (FAOR), and methanol oxidation reaction (MOR) are introduced. Many density

Minimizing the use of precious metal catalysts is important in many applications. Single-atom catalysts (SACs) have received much attention because all of the metal atoms can be used for surface reactions. However, SACs cannot catalyze some important reactions that require ensemble sites. Here, Rh catalysts were prepared by treating 2 wt % Rh/CeO₂ hydrothermally at 750 °C for 25 h. Nearly 100% dispersion was obtained, but the surface Rh atoms were not isolated (denoted as ENS). They c

Co3O4 is an attractive alternative to precious metal catalyst for CO oxidation due to its low cost and earth abundance, but its high catalytic activity is severely degraded in the presence of water. Here, we show that doping La into Co3O4 surfaces significantly enhances CO oxidation activity under moisture-rich condition. While bare Co3O4 is deactivated under moisture, the La-doped Co3O4 catalysts exhibit greatly improved activity and water resistance. The higher ratio of active Co3+ on the La-d

Abstract Single atomic Pt catalyst can offer efficient utilization of the expensive platinum and provide unique selectivity because it lacks ensemble sites. However, designing such a catalyst with high Pt loading and good durability is very challenging. Here, single atomic Pt catalyst supported on antimony‐doped tin oxide (Pt1/ATO) is synthesized by conventional incipient wetness impregnation, with up to 8 wt% Pt. The single atomic Pt structure is confirmed by high‐angle annular dark field scann

Wiederbelebte Aktivität: Platinnanopartikel (Kuboktaeder, Würfel und poröse Partikel, im Bild von links nach rechts) mit Alkylammoniumionen als Bedeckung sind durch Manipulation der Reduktionskinetik zugänglich. Diese Nanopartikel sind katalytisch aktiver als Nanopartikel, deren Form mithilfe von Polymeren und anderen Metallionen gesteuert wurde. Supporting information for this article is available on the WWW under http://www.wiley-vch.de/contents/jc_2001/2006/z603068_s.pdf or from the author. P

Nickel catalysts are typically used for hydrogen production by reforming reactions. Reforming methane with carbon dioxide, called dry reforming of methane (DRM), is a good way to produce hydrogen or syngas (a mixture of hydrogen and carbon monoxide) from two notable greenhouse gases. However, Ni catalysts used for DRM suffer from severe coke deposition. It has been known that small Ni nanoparticles are advantageous to reduce coke formation, but the high reaction temperature of DRM (800 °C) inevi

Single-atom catalysts (SACs) have emerged as promising materials in heterogeneous catalysis. Previous studies reported controversial results about the relative level in activity for SACs and nanoparticles (NPs). These works have focused on the effect of metal atom arrangement, without considering the oxidation state of the SACs. Here, we immobilized Pt single atoms on defective ceria and controlled the oxidation state of Pt SACs, from highly oxidized (Pt⁰ : 16.6 at %) to highly metall

Recent advances in heterogeneous single-atom catalysts (SACs), which have isolated metal atoms dispersed on a support, have enabled a more precise control of their surface metal atomic structure. SACs could reduce the amount of metals used for the surface reaction and have often shown distinct selectivity, which the corresponding nanoparticles would not have. However, SACs typically have the limitations of low-metal content, poor stability, oxidic electronic states, and an absence of ensemble si