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In photocatalysis,t he Schottky barrier in metalsemiconductor hybrids is knowntopromote charge separation, but acore-shell structure always leads to acharge build-up and eventually shuts off the photocurrent. Here,weshowthat Au-Cu 2 Oh ybrid nanostructures can be continuously tuned, particularly when the Cu 2 Od omains are single-crystalline. This is in contrast to the conventional systems,where the hybrid configuration is mainly determined by the choice of materials. The distal separation of the Au-Cu 2 Od omains in Janus nanostructures leads to enhanced charge separation and alarge improvement of the photocurrent. The activity of the Au-Cu 2 O Janus structures is 5times higher than that of the core-shell structure,a nd 10 times higher than that of the neat Cu 2 O nanocubes.T he continuous structural tuning allows to study the structure-property relationship and an optimization of the photocatalytic performance.

No abstract

We show that active surface growth is an effective method to create structural variety in the appending domain of Au seeds. The dynamic competition between the growth sites led to different Au hats on seeds.

Discovering new methods and principles in the inequivalent growth of equivalent facets is of great significance for going beyond symmetrical nanocrystals and for out-of-box exploration. In this work, we demonstrate that a middle ground exists between the traditional weak ligands and the strong ligands with unusual growth modes. By modifying the seed concentration during the growth of pentagonal Au nanorods, the typical weak ligand cetyltrimethylammonium bromide (CTAB) is made strong, leading to notches of restricted growth and even the active surface growth mode. In-depth investigation in the link between growth kinetics and ligand packing reveals the principle of their interplay --that the on-off dynamics of the ligands only allows for a certain limit of materials deposition rate. Beyond this limit, the growth materials build up and are then diverted elsewhere, leading to inequivalent growth. The fact that a freshly grown surface has few ligands promotes the active surface growth, focusing the growth materials onto a few sites. We believe that the knowhow of interfering ligand packing via growth kinetics would offer a powerful tool of synthetic control, where the facet-and curvature-dependent ligand packing is expected to be useful synthetic handles.

We demonstrate the regioselective growth of Au on Au nanobipyramids, either with etching of the tips, uniform coating except the tips, or forming a single island on the axial tip or an island on the equatorial corner. Importantly, the regioselectivity not only arises from the local curvature, as suggested by the recent literature, but also critically depends on the extent of ligand coverage on the seed surface. It is important to consider the competitive growth together with the curvature−ligand interplay: when there are insufficient ligands, they bind preferentially to the sharp tip for high surface energy, so that the remaining growth materials are diverted elsewhere; when the bipyramid is fully covered by ligands, the growth then selectively occurs at the tips because of the larger gaps among the ligands there. Our results demonstrate the great potentials in the rational design and synthesis when constructing sophisticated hybrid structures for functional nanomaterials.

The molar enthalpies of mixing for binary systems of choline chloride (chcl)/urea deep eutectic solvents (mole ratios of 1:1.5, 1:2, and 1:2.5) with water were measured at 308.15 and 318.15 K under atmospheric pressure with an isothermal calorimeter. The binary mixture of (chcl/urea (1:2.5) + water) showed endothermic behavior over the entire range of compositions, while the binary mixtures of (chcl/urea (1:1.5) + water) and (chcl/urea (1:2) + water) showed endothermic behavior first and then was changed to be exothermic with increasing content of deep eutectic solvents. The Redlich−Kister (RK) equation and the nonrandom twoliquid (NRTL) model were used to fit experimental molar enthalpies of mixing. The NRTL model with the fitted parameters was further used to predict the vapor pressure for the three systems and was compared with the experimental data from literature. For the binary mixtures of (chcl/urea (1:2) + water), the predicted vapor pressure agreed well with the experimental data only when the temperature was lower than 333.15 K and the mole fraction of chcl/urea (1:2) was lower than 0.1. Otherwise, the deviation increased greatly with an increase of the amount of chcl/urea (1:2).

Ligands are the primary tool for stabilizing nanoparticles and surface treatments. Understanding their relative strength and modulating their exchange are the initial steps towards their application. By real-time monitoring of...