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Cu-based nanocrystals are desirable for high efficiency catalysis, although they are easily oxidized under ambient conditions. Alloying Au and Cu provides the strategy for Cu-contained nanocrystals toward both high stability and high catalytic activity. However, a synthetic method of homogeneous alloy nanocrystals with tunable composition in aqueous solutions is lacking. Specific composition for achieving both enhanced stability and high catalytic activity remains elusive. Herein, coreduction of Au3+ and Cu2+ was performed through controlling the kinetics of the coreduction to form AuCu alloyed shells on the Au nanorod (NR) cores and obtain Au@AuCu NRs under the protection of nitrogen. The Cu atomic fraction (atom %) of the shell was finely tuned from 0 to 100% by controlling the fraction of Cu2+ cations in the growth solution. For Au@Au0.85Cu0.15 NRs, epitaxial growth of AuCu alloy on the Au NR was evidenced with about 4.0% lattice mismatch due to Cu alloying in the Au lattice by high-resolution transmission electron microscopy. Au@AuCu NRs with different aspect ratios were also obtained for tuning longitudinal plasmonic resonance. Stability characterization indicates that the Au@AuCu NRs with Cu atom % in the shell lower than 15% are of enhanced stability, while an increase in Cu atom % in the shell from 0 to 15.3 and 100% leads to dramatic reduction of the activation energy, Ea, of p-nitroaniline from 111 to 45 and 33 kJ/mol, respectively. Therefore, Au@Au0.85Cu0.15 NRs are preferable for high catalytic activity and enhanced stability. [ABSTRACT FROM AUTHOR]

Ruthenium (Ru) is known as the optimal metal catalyst for ammonia (NH3) synthesis, but the poor light-harvesting capability restricts its application in photocatalysis. Herein, we construct an antenna-reactor nanostructure through the controllable growth of an ultrathin Ru nanocluster shell with desired catalytic activity on the plasmonic gold (Au) nanoantennas. In this nanostructure, Au nanoantennas interact strongly with light to generate hot carriers, meanwhile Ru nanoclusters adsorb and activate N2, leading to the reduction of N2 to NH3 by the generated hot electrons. This antenna-reactor plasmonic photocatalyst exhibits shell-thickness-dependent photocatalytic activity toward nitrogen (N2) photofixation under visible and near-infrared light illumination. [ABSTRACT FROM AUTHOR]

Symmetry‐breaking synthesis of colloidal nanocrystals with desired structures and properties has aroused widespread interest in various fields, but the lack of robust synthetic protocols and the complex growth kinetics limit their practical applications. Herein, a general strategy is developed to synthesize the Au–Cu Janus nanocrystals (JNCs) through the site‐selective growth of Cu nanodomains on Au nanocrystals, which is directed by the substantial lattice mismatch between them, with the assistance of judicious manipulation of the growth kinetics. This strategy can work on Au nanocrystals with different architectures for the achievement of diverse asymmetric Au–Cu hybrid nanostructures. Of particular note, the obtained Au nanobipyramids (Au NBPs)‐based JNCs facilitate the conversion of CO2 to C2 hydrocarbon production during electrocatalysis, with the Faradaic efficiency and maximum partial current density being 4.1‐fold and 6.4‐fold higher than those of their monometallic Cu counterparts, respectively. The excellent electrocatalytic performances benefit from the special design of the Au–Cu Janus architectures and their tandem catalysis mechanism as well as the high‐index facets on Au nanocrystals. This research provides a new approach to synthesize various hybrid Janus nanostructures, facilitating the study of structure‐function relationship in the catalytic process and the rational design of efficient heterogeneous electrocatalysts. [ABSTRACT FROM AUTHOR]

Hybrid photocatalysts containing plasmonic metal and semiconductor building blocks can alleviate charge carrier recombination and broaden the range of light absorption of the semiconductor. In this work, plasmonic Au nanocrystals of different sizes and shapes (spheres and rods) are attached on graphitic carbon nitride (g-C3N4) nanosheets through electrostatic attraction. The effects of the morphology and loading amount of the Au nanocrystals are carefully studied for understanding and optimizing the hybrid photocatalysts. The optimized 18 nm-sized Au nanospheres/g-C3N4 photocatalyst exhibits a superior activity for H2 evolution at a rate of 540 μmol g−1 h−1 under visible light (λ ＞ 420 nm), exceeding those produced over larger-sized Au nanospheres/g-C3N4, Au nanorods/g-C3N4 and photodeposited Au nanoparticles/g-C3N4 photocatalysts. The excellent activity for H2 evolution is attributed to the electron sink and plasmonic effects of the Au nanocrystals in different spectral regions, as evidenced by photocurrent measurements. The introduced plasmonic Au nanocrystals not only enhance the photocatalytic activity, but they also endow the hybrid photocatalysts with an extended light absorption range. Our results and understanding will be useful for the design of efficient plasmonic photocatalysts for solar to fuel energy conversion as well as for other plasmon-driven chemical reactions. [ABSTRACT FROM AUTHOR]

Transition metal phosphides have sparked considerable interest as electrocatalysts owing to their excellent catalytic activities towards water splitting. However, the development of a general strategy for the preparation of metal phosphides has remained challenging. In this work, we demonstrate a two-step, aerosol spray-based strategy for the synthesis of various mesoporous monometallic and multimetallic phosphide microspheres. Four monometallic (FeP, CoP, Ni2P, and Cu3P), one bimetallic (Co6Ni4P5) and one trimetallic (Co4Ni3Cu2P10) phosphide samples are successfully prepared, suggesting the generality of our method. In addition, the CoP sample is found to be an excellent material for the hydrogen evolution reaction over a wide pH range through the introduction of corrosion-resistant Cr2O3. On the other hand, its catalytic activity can be switched to the oxygen evolution reaction in combination with Fe2O3. The overpotential for the oxygen evolution reaction to generate a current density of 10 mA cm−2 is as low as 302 mV. This activity can be maintained for at least 50 h. More importantly, a two-electrode electrolyzer constructed from 10% Cr–CoP and 30% Fe–CoP samples delivers a current density of 100 mA cm−2 at a cell voltage of merely 1.67 V, showing the use of these cost-effective materials for bifunctional water splitting. [ABSTRACT FROM AUTHOR]

The synthesis of anisotropic metal nanostructures is strongly desired for exploring plasmon-enabled applications. Herein, the preparation of anisotropic Au/SiO2 and Au/SiO2/Pd nanostructures is realized through selective silica coating on Au nanobipyramids. For silica coating at the ends of Au nanobipyramids, the amount of coated silica and the overall shape of the coated nanostructures exhibit a bell-shaped dependence on the cationic surfactant concentration. For both end and side silica coating on Au nanobipyramids, the size of the silica component can be varied by changing the silica precursor amount. Silica can also be selectively deposited on the corners or facets of Au nanocubes, suggesting the generality of this method. The blockage of the predeposited silica component on Au nanobipyramids enables further selective Pd deposition. Suzuki coupling reactions carried out with the different bimetallic nanostructures functioning as plasmonic photocatalysts indicate that the plasmonic photocatalytic activity is dependent on the site of Pd nanoparticles on Au nanobipyramids. Taken together, these results suggest that plasmonic hot spots play an important role in hot-electron-driven plasmonic photocatalysis. This study opens up a promising route to the construction of anisotropic bimetallic nanostructures as well as to the design of bimetallic plasmonic-catalytic nanostructures as efficient plasmonic photocatalysts. [ABSTRACT FROM AUTHOR]

Developing photocatalysts that can efficiently produce hydrogen from water under solar irradiation is highly desired for sustainable and clean hydrogen energy. Herein, it is demonstrated that (TiO2(B) nanosheet)/(metallic phase MoS2) hybrid nanostructures have high activity for photocatalytic hydrogen evolution from water. The TiO2(B) nanosheets are prepared by solvothermal reaction with TiCl3 as a precursor in the presence of ethylene glycol. Due to the short transportation distance of charge carriers, more negative conduction band edge, and the existence of oxygen vacancy, the photocatalytic activity of the pure TiO2(B) nanosheets is one order of the magnitude larger than that of the commercial P25. After loading metallic phase MoS2, the photocatalytic activity of TiO2(B) is further improved by ≈13 times to 1444 μmol g−1 h−1 because of the superior activity of metallic phase MoS2 for hydrogen evolution. The findings provide a cost‐effective and highly active photocatalyst for hydrogen production from water and are very helpful for the development of sustainable and clean hydrogen energy. [ABSTRACT FROM AUTHOR]

Metal oxide nanostructures represent a large class of dielectric nanomaterials with high or moderate refractive indexes. Dielectric nanomaterials have recently attracted much attention in the field of all‐dielectric nanophotonics. They can support both electric and magnetic resonances without suffering from high losses or heating as their plasmonic counterparts. Although various intriguing optical effects have been discovered on dielectric nanostructures, a real challenge in this field is the difficulty in the production of dielectric nanostructures with well‐defined geometry, smooth surface, moderate/high refractive indexes, and good crystallinity. In this work, using an aerosol spray method and subsequent thermal treatment, smooth‐surfaced metal oxide spheres that span a broad size range from 100 nm to several micrometers in diameter and a relatively wide refractive index range from 2 to 2.35 in the visible region have been successfully synthesized. In particular, they are shown to support strong electric and magnetic resonances of different orders in excellent agreement with Mie theory, which is a signature of their outstanding optical performance. The findings offer many possibilities for a wide variety of low‐loss optical components, from Mie‐type nanoresonators and whispering gallery cavities to micrometer lenses. [ABSTRACT FROM AUTHOR]