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 increased. These results demonstrate that the photogenerated electron transfer and the resulting catalytic activity of the composites can be controlled by the size of the mediating gold capacitors.

The electron-transfer dynamics between nanoparticles has been studied as a function of interparticle distance by in situ voltammetry of well-defined monolayers of a metal quantum dot nanoparticle Au38(hexanethiolate)24. The interparticle distance is precisely controlled by the Langmuir technique and addition of various lengths of dithiol linkers (HS(CH2)nSH; n = 5, 6, 8, and 9). Voltammograms of Au38 monolayers display a well-defined single-electron charging peak that increases remarkably with decreasing the interparticle distance. The diffusion coefficient and rate constant calculated from the peak current for core-core electron hopping reaction both exponentially increase respectively, from 3.3 x 10-10 to 5.2 x 10-9 cm2/s and 2.2 x 104 to 5.0 x 105 s-1 as the distance decreases from 13.3 to 9.5 A and then levels off at 8.0 A. These rate constants are in good agreement with the literature values, demonstrating that the present experimental approach provides a powerful way to investigate the correlation between the electron-transfer dynamics and nanoparticle assembly structure.

Electrocatalytic CO 2 reduction reaction (CO 2 RR) is greatly facilitated by Au surfaces. However, large fractions of underlying Au atoms are generally unused during the catalytic reaction, which limits mass activity. Herein, we report a strategy for preparing efficient electrocatalysts with high mass activities by the atomic-level transplantation of Au active sites into a Ni 4 nanocluster (NC). While the Ni 4 NC exclusively produces H 2 , the Au-transplanted NC selectively produces CO over H 2 . The origin of the contrasting selectivity observed for this NC is investigated by combining operando and theoretical studies, which reveal that while the Ni sites are almost completely blocked by the CO intermediate in both NCs, the Au sites act as active sites for CO 2 -to-CO electroreduction. The Au-transplanted NC exhibits a remarkable turnover frequency and mass activity for CO production (206 mol CO /mol NC /s and 25,228 A/g Au , respectively, at an overpotential of 0.32 V) and high durability toward the CO 2 RR over 25 h.

Incidence of VTAs showed marked circadian variations with night-time peaks in patients with ERS and BS.

Ultrasmall gold nanoclusters (Au NCs) have recently gained enormous popularity as a newly emerging light harvester, but many fundamental aspects of their photoelectrochemical behavior are still largely unknown. Unlike traditional photoactive nanoparticles, the NC's core structure, rather than its size, is a key factor that dictates the physical properties of NCs because of a strong quantum confinement effect. Despite this importance, no effort has been made to elucidate the effect of the core structure on the photoelectrochemistry of Au NC-sensitized TiO 2 (Au NC−TiO 2 ). Using Au 25 NC as a model system, we delicately tailored the icosahedral Au 13 core of Au 25 NC into a cuboctahedral Au 15 core of Au 23 NC. This subtle core manipulation has a drastic impact on the entire interfacial behavior of Au NC−TiO 2 , which in turn significantly affects the photoelectrochemical performance. This new insight highlights the overlooked effect of the core structure on the photoelectrochemistry of Au NC−TiO 2 .