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Plasmonic hot spots located among closely dispersed plasmonic nanoparticles (NPs) are intensively studied for efficient conversion of solar to chemical or electrical energy applications. Here, a successful method to synthesize high-density unaggregated plasmonic Ag or Au NPs (AgNPs or AuNPs) onto nanostructured semiconductors with 3D densely organized NPs is demonstrated. The densely dispersed plasmonic AgNPs or AuNPs are assembled chemically on the entire surface of the ZnO nanorods through bifunctional thioctic acid bridging linkers. The fabricated NPs possessing small interparticle gaps generate numerous plasmonic hot spots which boost catalytic activities of the photocatalysts. As depicted by exact 3D finite-difference time domain simulations, the electromagnetic fields are magnified exponentially among interparticle gaps, hot spots, due to the plasmonic coupling effects of the neighboring AgNPs. The electromagnetic fields are strengthened by decreasing the interparticle spacing of coupled AgNPs. It is consistent with the result that the photocatalytic reaction rate increases non-linearly with the Ag content under full-spectrum light irradiation. Using the spectral characterizations and electromagnetic field simulations, we unambiguously confirm the enhancement of photoactivity due to coupling of plasmonic hot spot effect to nanostructured semiconductors. Moreover, diverse heterostructures based on the plasmonic NPs on various ZnO nanostructures (films, nanorod arrays, branched nanowires, and mesoporous structures) or functional materials (CuInGaSe2 absorber films, multiferroic BiFeO3 films, visible-light photoactive Cu2S and CdS nanorods) are successfully fabricated using the present synthesis methodology.

Abstract: Electron field emission, electrons emitted from solid surfaces under high electric field, offers significant scientific interests in materials sciences and potential optoelectronics applications. 2D atomic layers, such as MoS2, exhibit fascinating properties for diverse applications in next‐generation nanodevices and rich physical phenomena for fundamental research. However, the study on field emission of semiconducting monolayers is lacking owing to its low efficiency and stability of electron emission. Here, electron field emission of the geometrically modulated monolayer semiconductors suspended with 1D nanoarrays is demonstrated. Chemical vapor deposition synthesis of two prototype monolayers of transition metal dichalcogenides (TMD), MoS2 and MoSe2, is presented and their diverse band structures offer an ideal platform to explore the fundamental process of the electron emission in the TMD. Geometrical modulation and charge transfer of the semiconducting monolayers can be significantly tuned with the structural suspension with the 1D ZnO nanoarrays. Possible mechanisms on the enhanced electron emission of the 2D monolayers are discussed. With geometrical control of the monolayers, a highly efficient and stable electron emission of TMD monolayers is achieved in low turn‐on electric fields, enabling applications on electrons sources and opening a new avenue toward geometrically tuned atomic layers. [ABSTRACT FROM AUTHOR]

The shape of Ag2O crystals that evolve from edge and corner-truncated cubes into rhombicuboctahedrons, then to hexapods can be conducted precisely by simply controlling the amount of AgNO3, NH4NO3 and NaOH precursors. The edge and corner-truncated cube crystals possess the highest photocatalytic activity, followed by the rhombicuboctahedrons, then the hexapods. The photocatalytic activity of the Ag2O crystals depends greatly on the type of the exposed facets. The {1 0 0} facets exhibit the highest photocatalytic activity in methyl orange solution under full-spectrum light irradiation, followed by the {1 1 0} facets, then the {1 1 1} facets. The {1 0 0} facets are also demonstrated to show intense susceptibility toward etching by NH3. [ABSTRACT FROM AUTHOR]

Two‐dimensional (2D) nanomaterials are widely recognized as an important class of functional materials possessing superior electrochemical reaction kinetics. Herein, an L‐aspartic acid (AA)‐modified graphene oxide (GO) templating strategy is developed to in situ yield ultrathin (i.e., ≈5 nm) cobalt carbonate hydroxide (Co2(OH)2CO3) nanosheets as advanced anode materials of lithium ion batteries. Notably, the covalent tethering of AA on the GO surface renders a high density of carboxyl groups that impart effective loading of Co‐containing precursors and subsequent growth into Co2(OH)2CO3 nanosheets bridging adjacent GO layers. The lasagna‐like Co2(OH)2CO3‐GO nanocomposites exhibit an ultrahigh lithium storage capacity of 1770 mAh g−1 after 500 cycles at 100 mA g−1. It is noteworthy that the cycled Co2(OH)2CO3 phase separates into homogeneously dispersed Co(OH)2 and CoCO3 phases with two different charge plateaus at ≈1.2 and 2.0 V, respectively, which effectively inhibit large‐scale homophase coarsening of Co, Li2CO3, and LiOH. The much shortened Li+/e− transfer distance enabled by individual ultrathin Co2(OH)2CO3 nanosheet together with robust layer‐by‐layer assembled nanostructure of Co2(OH)2CO3‐GO confers the superior electrochemical reactivity and mechanical stability. As such, the amino acid‐modified GO templating strategy may represent a simple yet robust means of crafting a variety of 2D nanostructured composites of interest for energy storage applications. [ABSTRACT FROM AUTHOR]

Despite impressive recent advances in the synthesis of lead chalcogenide solid nanoparticles, there are no examples of lead chalcogenide hollow nanoparticles (HNPs) with controlled diameter and shell thickness as current synthetic approaches for HNPs have inherent limitations associated with their complexity, inability to precisely control the dimensions, and limited possibilities with regard to applicable materials. Herein, we report on an unconventional strategy for crafting uniform lead chalcogenide (PbS and PbTe) HNPs with tailorable size, surface chemistry, and near-IR absorption. Amphiphilic star-like triblock copolymers [polystyrene-block-poly(acrylic acid)-block-polystyrene and polystyrene-block-poly(acrylic acid)-block-poly(3,4-ethylenedioxythiophene)] were rationally synthesized and exploited as nanoreactors for the formation of uniform PbS and PbTe HNPs. Compared to their solid counterparts, the near-IR absorption of the HNPs is blue-shifted owing to the hollow interior. This strategy can be readily extended to other types of intriguing low-band-gap HNPs for diverse applications., (© 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)