Sang Woo Han

Abstract Hollow tin dioxide (SnO 2 ) microspheres were synthesized by the simple heat treatment of a mixture composed of tin( IV ) tetrachloride pentahydrate (SnCl 4 ·5H 2 O) and resorcinol–formaldehyde gel (RF gel). Because hollow structures were formed during the heat treatment, the pre‐formation of template and the adsorption of target precursor on template are unnecessary in the current method, leading to simplified synthetic procedures and facilitating mass production. Field‐emission scanni

Pd-Pt alloy nanocrystals (NCs) with hollow structures such as nanocages with porous walls and dendritic hollow structures and Pd@Pt core-shell dendritic NCs could be selectively synthesized by a galvanic replacement method with uniform Pd octahedral and cubic NCs as sacrificial templates. Fine control over the degree of galvanic replacement of Pd with Pt allowed the production of Pd-Pt NCs with distinctly different morphologies. The synthesized hollow NCs exhibited considerably enhanced oxygen r

Octahedral Au@Pd core-shell nanoparticles have been prepared by a one-step aqueous synthesis method where both metal precursors are present simultaneously with the use of cetyltrimethylammonium chloride as both reductant and stabilizer.

Dendritic Au−Pd alloy nanoparticles were synthesized in high yield through the coreduction of HAuCl 4 and K 2 PdCl 4 in aqueous solutions by using hydrazine as a reducing agent. Relative compositions between Au and Pd at the particle surfaces as well as in bulk phases could be modulated by controlling the molar ratios between metal precursors in the feeding solutions. The formation of nanodendrites may be the result of the fast reduction rate of metal ions and subsequent fast, kinetically contro

A synthesis strategy for the preparation of ultrathin free-standing ternary-alloy nanosheets is reported. Ultrathin Pd-Pt-Ag nanosheets with a thickness of approximately 3 nm were successfully prepared by co-reduction of the metal precursors in an appropriate molar ratio in the presence of CO. Both the presence of CO and the interplay between the constituent metals provide fine control over the anisotropic two-dimensional growth of the ternary-alloy nanostructure. The prepared Pd-Pt-Ag nanosheet

The development of an efficient synthesis method to produce multimetallic nanoparticles (NPs) with a desirable structure is strongly required to clarify the structure-composition-property relationship of NPs and to investigate their possible applications. However, the controlled synthesis of NPs consisting of multiple (n ≥ 3) noble metal components has been relatively unexplored in comparison to bimetallic NPs. In the present work, we have demonstrated a facile one-pot aqueous approach for the c

Die Mischung macht's: Au-Pd-Legierungs-, Au@Pd-Kern-Schale-, Pd- und Au-Nanokristalle (NCs) mit identischer Oktaederform und ähnlicher Größe wurden hergestellt, um speziell die Auswirkung der Atomverteilung auf die Leistungsfähigkeit von NC-Katalysatoren zu studieren. Für die Oxidation von Ameisensäure wurde eine starke Abhängigkeit der Aktivitäten und Stabilitäten dieser NCs gefunden: Au–Pd (Legierung) > Au@Pd (Kern-Schale) > Pd ≫ Au. Detailed facts of importance to specialist readers are publi

In the mix: Au–Pd alloy, Au@Pd core–shell, Pd, and Au nanocrystals (NCs) with an identical octahedral shape and with similar NC size were prepared to examine exclusively the effect of atomic distribution on the catalytic performance of NCs (see picture). The catalytic activities and stabilities toward formic acid oxidation highly depend on the atomic distribution in the NCs: Au–Pd alloy > Au@Pd core–shell > Pd ≫ Au NCs.

Au nanocrystals (NCs) with an unprecedented hexoctahedral structure enclosed exclusively by high-index {321} facets have been prepared for the first time. Manipulating the NC growth kinetics by controlling the amount of reductant and the reaction temperature in the presence of a suitable surfactant was the key synthetic lever for controlling the morphology of the Au NCs. The hexoctahedral Au NCs exhibited efficient optical and surface-enhanced Raman scattering activities due to their unique morp

Precise control over the topology of plasmonic metal–semiconductor heteronanostructures is essential for fully harnessing their plasmonic function and hence for designing innovative solar energy conversion platforms. Here, we present a rational synthesis strategy for the realization of plasmonic metal–semiconductor heteronanocrystals with intended configurations through the site-selective overgrowth of semiconductor Cu 2 O on desired sites of anisotropic Au nanocrystals. Both the exploitation of

A facile synthesis of flower-shaped porous Au−Pd alloy nanoparticles with ascorbic acid as a reductant and PVP as a stabilizing agent is presented. The alloy nanoparticles were prepared from the aqueous solutions of HAuCl 4 /K 2 PdCl 4 mixtures in molar ratios of 3:1, 1:1, and 1:3. The size, structure, optical properties, and composition distribution of the synthesized Au−Pd alloy nanoparticles were characterized by transmission electron microscopy, energy-dispersive X-ray spectroscopy, UV−vis s

The core of the matter: The catalytic activities of [email protected] heteronanostructures (see scheme; CTAB: cetyltrimethylammonium bromide, NPs: nanoparticles) toward oxygen reduction are highly dependent on the shape of the cores, thus revealing the importance of the core structure for enhancing the activity of core–shell-type nanocatalysts. Detailed facts of importance to specialist readers are published as ”Supporting Information”. Such documents are peer-reviewed, but not copy-edited or ty

We have investigated comparative adsorptivities and relative stabilities of self-assembled monolayers of thiol (benzenethiol, BT) vs selenol (benzeneselenol, BSe) on a silver surface by diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy and surface-enhanced Raman spectroscopy (SERS). BT and BSe are chemisorbed on silver as benzenethiolate and benzeneselenolate, respectively, after deprotonation with a tilted orientation with respect to the substrate surface; the benzene rings of

The many faces of noble metals: Through the simultaneous reduction of Au and Pd ions in the presence of octahedral Au nanocrystal (NC) seeds, hexoctahedron-like convex Au@Pd core–shell NCs, enclosed predominantly by high-index {12 5 3} facets, were synthesized under aqueous room-temperature conditions (see picture). The convex Au@Pd NCs showed much higher electrocatalytic properties toward ethanol oxidation than other types of Au@Pd NCs. Detailed facts of importance to specialist readers are pub