Dongil Lee

Luminescent nanomaterials have captured the imagination of scientists for a long time and offer great promise for applications in organic/inorganic light-emitting displays, optoelectronics, optical sensors, biomedical imaging, and diagnostics. Atomically precise gold clusters with well-defined core-shell structures present bright prospects to achieve high photoluminescence efficiencies. In this study, gold clusters with a luminescence quantum yield greater than 60% were synthesized based on the

This paper describes electrochemical and spectroscopic properties of a well-characterized, synthetically accessible, 1.1 nm diam Au nanoparticle, Au(38)(PhC(2)S)(24), where PhC(2)S is phenylethylthiolate. Properties of other Au(38) nanoparticles made by exchanging the monolayer ligands with different thiolate ligands are also described. Voltammetry of the Au(38) nanoparticles in CH(2)Cl(2) reveals a 1.62 V energy gap between the first one-electron oxidation and the first reduction. Based on a ch

Thiolate-protected metal nanoparticles containing a few to few hundred metal atoms are interesting materials exhibiting unique physicochemical properties. They encompass the bulk-to-molecule transition region, where discrete electronic states emerge and electronic band energetics yield to quantum confinement effects. Recent progresses in the synthesis and characterization of ultrasmall gold nanoparticles have opened up new avenues for the isolation of extremely monodispersed nanoparticles with a

Copper electrocatalysts can reduce CO 2 to hydrocarbons at high overpotentials. However, a mechanistic understanding of CO 2 reduction on nanostructured Cu catalysts has been lacking. Herein we show that the structurally precise ligand-protected Cu-hydride nanoclusters, such as Cu 32 H 20 L 12 (L is a dithiophosphate ligand), offer unique selectivity for electrocatalytic CO 2 reduction at low overpotentials. Our density functional theory (DFT) calculations predict that the presence of the negati

Abstract The theoretically predicted volcano plot for hydrogen production shows the best catalyst as the one that ensures that the hydrogen binding step is thermodynamically neutral. However, the experimental realization of this concept has suffered from the inherent surface heterogeneity of solid catalysts. It is even more challenging for molecular catalysts because of their complex chemical environment. Here, we report that the thermoneutral catalyst can be prepared by simple doping of a plati

We present a systematic study of optical properties of a series of hexanethiolate-capped Au clusters of varying sizes using femtosecond transient absorption, time-resolved fluorescence, and two-photon absorption cross-sectional measurements. An abrupt change in optical properties and their trends has been found at the 2.2 nm size. Displacively excited vibrations with a period of 450 fs have been detected in the transient absorption signal for smaller clusters < or = 2.2 nm. These results strongl

This Letter describes size-controlled photocatalytic activity of ZnO nanoparticles coated with glutathione-protected gold nanoparticles with diameters of 1.1, 1.6, and 2.8 nm. The photocatalytic activity of the ZnO–Au composites was found to increase with increasing gold size for both oxidative and reductive catalytic reactions. Photoluminescence decay dynamics of the composites showed that the electron-transfer rate from the photoexcited ZnO to gold nanoparticle also increased as the gold size

The exceptional stability of thiolate-protected Au25 clusters, [Au25(SR)18](-), arises from the closure of superatomic electron shells, leading to a noble-gas-like 8-electron configuration (1S(2)1P(6)). Here we present that replacing the core Au atom with Pd or Pt results in stable [MAu24(SR)18](0) clusters (M = Pd, Pt) having a superatomic 6-electron configuration (1S(2)1P(4)). Voltammetric studies of [PdAu24(SR)18](0) and [PtAu24(SR)18](0) reveal that the highest occupied molecular orbital-low

Abstract Accurate identification of active sites is critical for elucidating catalytic reaction mechanisms and developing highly efficient and selective electrocatalysts. Herein, we report the atomic‐level identification of active sites using atomically well‐defined gold nanoclusters (Au NCs) Au 25 , Au 38 , and Au 144 as model catalysts in the electrochemical CO 2 reduction reaction (CO 2 RR). The studied Au NCs exhibited remarkably high CO 2 RR activity, which increased with increasing NC size

Well-defined Au/ZnO nanoparticle composites were prepared by modifying ZnO with preformed Au nanoparticles protected with bifunctional glutathione ligand. In this approach, the Au nanoparticles were highly monodisperse and their loading on ZnO surface could be precisely controlled by the anchoring conditions. Steady-state and time-resolved photoluminescence of the composites revealed the ability of the Au nanoparticles to efficiently extract conduction band electrons from the photoexcited ZnO. T

Development of efficient and selective electrocatalysts is a key challenge to achieve an industry-relevant electrochemical CO2 reduction reaction (CO2RR) to produce commodity chemicals. Here, we report that Au25 clusters with Au-thiolate staple motifs can initiate electrocatalytic reduction of CO2 to CO with nearly zero energy loss and achieve a high CO2RR current density of 540 mA cm–2 in a gas-phase reactor. Electrochemical kinetic investigations revealed that the high CO2RR activity of the Au

Ionic liquids are room-temperature molten salts that are increasingly used in electrochemical devices, such as batteries, fuel cells, and sensors, where their intrinsic ionic conductivity is exploited. Here we demonstrate that combining anionic, redox-active Au25 clusters with imidazolium cations leads to a stable ionic liquid possessing both ionic and electronic conductivity. The Au25 ionic liquid was found to act as a versatile matrix for amperometric enzyme biosensors toward the detection of

The energy gap law relates the nonradiative decay rate to the energy gap separating the ground and excited states. Here we report that the energy gap law can be applied to exciton dynamics in gold cluster molecules. Size-dependent electrochemical and optical properties were investigated for a series of n -hexanethiolate-protected gold clusters ranging from Au 25 to Au 333 . Voltammetric studies reveal that the highest occupied molecular orbital-lowest unoccupied molecular orbital (HOMO–LUMO) gap

Novel Au 25 (C 6 S) 17 PyS clusters (pyrene-functionalized Au 25 clusters) showing interesting electrochemical and optical properties are synthesized and characterized. Significant fluorescence quenching is observed for pyrene attached to Au 25 clusters, suggesting strong excited-state interactions. Time-resolved fluorescence upconversion and transient absorption measurements are utilized to understand the excited-state dynamics and possible interfacial electron- and energy-transfer pathways. El

This paper describes the effects of doped metals on hydrogen evolution reaction (HER) electrocatalyzed by atomically controlled MAu₂₄ and M₂Au₃₆ nanoclusters, where M = Pt and Pd. HER performances, such as onset potential ( E_onset), catalytic current density, and turnover frequency (TOF), are comparatively examined with respect to the doped metals. Doping Pt or Pd into gold nanoclusters not only changes the electrochemical redox potentials of nanoclust