Exploration of low‐cost and earth‐abundant photocatalysts for highly efficient solar photocatalytic water splitting is of great importance. Although transition‐metal dichalcogenides (TMDs) showed ...outstanding performance as co‐catalysts for the hydrogen evolution reaction (HER), designing TMD‐hybridized photocatalysts with abundant active sites for the HER still remains challenge. Here, a facile one‐pot wet‐chemical method is developed to prepare MS2–CdS (M=W or Mo) nanohybrids. Surprisedly, in the obtained nanohybrids, single‐layer MS2 nanosheets with lateral size of 4–10 nm selectively grow on the Cd‐rich (0001) surface of wurtzite CdS nanocrystals. These MS2–CdS nanohybrids possess a large number of edge sites in the MS2 layers, which are active sites for the HER. The photocatalytic performances of WS2–CdS and MoS2–CdS nanohybrids towards the HER under visible light irradiation (>420 nm) are about 16 and 12 times that of pure CdS, respectively. Importantly, the MS2–CdS nanohybrids showed enhanced stability after a long‐time test (16 h), and 70 % of catalytic activity still remained.
A single layer makes the difference: MS2–CdS (M=W or Mo) nanohybrids with single‐layer MS2 nanosheets selectively grown on the Cd‐rich (0001) surface of wurtzite CdS nanocrystals (see picture) are synthesized by a facile one‐pot wet‐chemical method. The MS2–CdS nanohybrids showed excellent photocatalytic activity towards the hydrogen evolution reaction and good stability.
Yolk/shell particles possess a unique structure that is composed of hollow shells that encapsulate other particles but with an interstitial space between them. These structures are different from ...core/shell particles in that the core particles are freely movable in the shell. Yolk/shell particles combine the properties of each component, and can find potential applications in catalysis, lithium ion batteries, and biosensors. In this Research News article, a soft‐template‐assisted method for the preparation of yolk/silica shell particles is presented. The demonstrated method is simple and general, and can produce hollow silica spheres incorporated with different particles independent of their diameters, geometry, and composition. Furthermore, yolk/mesoporous silica shell particles and multishelled particles are also prepared through optimization of the experimental conditions. Finally, potential applications of these particles are discussed.
A mixture of anionic and zwitterionic surfactants was used as soft templates for the preparation of yolk/silica shell particles. Moreover, it is demonstrated that yolk/mesoporous silica shell particles and multishelled particles can be synthesized by this strategy (see figure).
Nanostructured transition metal dichalcogenides (TMDs) are proven to be efficient and robust earth‐abundant electrocatalysts to potentially replace precious platinum‐based catalysts for the hydrogen ...evolution reaction (HER). However, the catalytic efficiency of reported TMD catalysts is still limited by their low‐density active sites, low conductivity, and/or uncleaned surface. Herein, a general and facile method is reported for high‐yield, large‐scale production of water‐dispersed, ultrasmall‐sized, high‐percentage 1T‐phase, single‐layer TMD nanodots with high‐density active edge sites and clean surface, including MoS2, WS2, MoSe2, Mo0.5W0.5S2, and MoSSe, which exhibit much enhanced electrochemical HER performances as compared to their corresponding nanosheets. Impressively, the obtained MoSSe nanodots achieve a low overpotential of −140 mV at current density of 10 mA cm−2, a Tafel slope of 40 mV dec−1, and excellent long‐term durability. The experimental and theoretical results suggest that the excellent catalytic activity of MoSSe nanodots is attributed to the high‐density active edge sites, high‐percentage metallic 1T phase, alloying effect and basal‐plane Se‐vacancy. This work provides a universal and effective way toward the synthesis of TMD nanostructures with abundant active sites for electrocatalysis, which can also be used for other applications such as batteries, sensors, and bioimaging.
A general and facile method is developed for high‐yield, large‐scale production of water‐dispersed, ultrasmall, high‐percentage 1T‐phase, single‐layer transition metal dichalcogenide nanodots with high‐density active edge sites and clean surface, including MoS2, WS2, MoSe2, Mo0.5W0.5S2, and MoSSe, which exhibit much enhanced electrochemical hydrogen evolution reaction performances as compared to their corresponding nanosheets.
Semiconducting nanosheets with microscale lateral size are attractive building blocks for the fabrication of electronic and optoelectronic devices. The phase‐controlled chemical synthesis of ...semiconducting nanosheets is of particular interest, because their intriguing properties are not only related to their size and shape, but also phase‐dependent. Herein, a facile method for the synthesis of phase‐pure, microsized, two‐dimensional (2D) CuSe nanosheets with an average thickness of approximately 5 nm is demonstrated. These hexagonal‐phased CuSe nanosheets were transformed into cubic‐phased Cu2−xSe nanosheets with the same morphology simply by treatment with heat in the presence of CuI cations. The phase transformation, proposed to be a template‐assisted process, can be extended to other systems, such as CuS and Cu1.97S nanoplates. Our study offers a new method for the phase‐controlled preparation of 2D nanomaterials, which are not readily accessible by conventional wet‐chemical methods.
Not fazed by change: A facile solution‐based strategy was used for the preparation of microsized CuSe nanosheets. As‐prepared CuSe with a hexagonal phase was transformed into Cu2−xSe with a cubic phase through simple treatment with heat without damaging the shape of the original 2D nanosheets (see picture). The two kinds of nanosheets show different optical properties and are both promising building blocks for the construction of various devices.
Crystal-phase engineering offers opportunities for the rational design and synthesis of noble metal nanomaterials with unusual crystal phases that normally do not exist in bulk materials. However, it ...remains a challenge to use these materials as seeds to construct heterometallic nanostructures with desired crystal phases and morphologies for promising applications such as catalysis. Here, we report a strategy for the synthesis of binary and ternary hybrid noble metal nanostructures. Our synthesized crystal-phase heterostructured 4H/fcc Au nanowires enable the epitaxial growth of Ru nanorods on the 4H phase and fcc-twin boundary in Au nanowires, resulting in hybrid Au-Ru nanowires. Moreover, the method can be extended to the epitaxial growth of Rh, Ru-Rh and Ru-Pt nanorods on the 4H/fcc Au nanowires to form unique hybrid nanowires. Importantly, the Au-Ru hybrid nanowires with tunable compositions exhibit excellent electrocatalytic performance towards the hydrogen evolution reaction in alkaline media.
Phase engineering of nanomaterials (PEN) offers a promising route to rationally tune the physicochemical properties of nanomaterials and further enhance their performance in various applications. ...However, it remains a great challenge to construct well‐defined crystalline@amorphous core–shell heterostructured nanomaterials with the same chemical components. Herein, the synthesis of binary (Pd‐P) crystalline@amorphous heterostructured nanoplates using Cu3−χP nanoplates as templates, via cation exchange, is reported. The obtained nanoplate possesses a crystalline core and an amorphous shell with the same elemental components, referred to as c‐Pd‐P@a‐Pd‐P. Moreover, the obtained c‐Pd‐P@a‐Pd‐P nanoplates can serve as templates to be further alloyed with Ni, forming ternary (Pd‐Ni‐P) crystalline@amorphous heterostructured nanoplates, referred to as c‐Pd‐Ni‐P@a‐Pd‐Ni‐P. The atomic content of Ni in the c‐Pd‐Ni‐P@a‐Pd‐Ni‐P nanoplates can be tuned in the range from 9.47 to 38.61 at%. When used as a catalyst, the c‐Pd‐Ni‐P@a‐Pd‐Ni‐P nanoplates with 9.47 at% Ni exhibit excellent electrocatalytic activity toward ethanol oxidation, showing a high mass current density up to 3.05 A mgPd−1, which is 4.5 times that of the commercial Pd/C catalyst (0.68 A mgPd−1).
Binary (Pd‐P) and ternary (Pd‐Ni‐P) nanoplates, both with crystalline@amorphous core–shell nanostructures, are synthesized using Cu3−χP nanoplates as templates. The obtained c‐Pd‐Ni‐P@a‐Pd‐Ni‐P heterostructured nanoplates exhibit superior electrocatalytic performance toward the ethanol oxidation reaction in alkaline media compared to c‐Pd‐P@a‐Pd‐P heterostructured nanoplates and commercial Pd/C catalysts.
Two‐dimensional (2D) copper‐based ternary and quaternary semiconductors are promising building blocks for the construction of efficient solution‐processed photovoltaic devices at low cost. However, ...the facile synthesis of such 2D nanoplates with well‐defined shape and uniform size remains a challenge. Reported herein is a universal template‐mediated method for preparing copper‐based ternary and quaternary chalcogenide nanoplates, that is, CuInS2, CuInxGa1−xS2, and Cu2ZnSnS4, by using a pre‐synthesized CuS nanoplate as the starting template. The various synthesized nanoplates are monophasic with uniform thickness and lateral size. As a proof of concept, the Cu2ZnSnS4 nanoplates were immobilized on a Mo/glass substrate and used as semiconductor photoelectrode, thus showing stable photoelectrochemical response. The method is general and provides future opportunities for fabrication of cost‐effective photovoltaic devices based on 2D semiconductors.
Step up to the nanoplate: A facile and general method was used to synthesize monodispersed copper‐based ternary and quaternary semiconducting nanoplates (i.e., CuInxGa1−xS2 and Cu2ZnSnS4) with pre‐synthesized ultrathin CuS nanoplates as a template. The obtained nanoplates had tunable optical properties, and a photoelectrochemical device based on Cu2ZnSnS4 nanoplates demonstrated promise for photovoltaic devices.
Selective hydrogenation of nitrostyrenes is a great challenge due to the competitive activation of the nitro groups (─NO2) and carbon–carbon (C═C) double bonds. Photocatalysis has emerged as an ...alternative to thermocatalysis for the selective hydrogenation reaction, bypassing the precious metal costs and harsh conditions. Herein, two crystalline phases of layered ternary sulfide Cu2WS4, that is, body‐centered tetragonal I‐Cu2WS4 nanosheets and primitive tetragonal P‐Cu2WS4 nanoflowers, are controlled synthesized by adjusting the capping agents. Remarkably, these nanostructures show visible‐light‐driven photocatalytic performance for selective hydrogenation of 3‐nitrostyrene under mild conditions. In detail, the I‐Cu2WS4 nanosheets show excellent conversion of 3‐nitrostyrene (99.9%) and high selectivity for 3‐vinylaniline (98.7%) with the assistance of Na2S as a hole scavenger. They also can achieve good hydrogenation selectivity to 3‐ethylnitrobenzene (88.5%) with conversion as high as 96.3% by using N2H4 as a proton source. Mechanism studies reveal that the photogenerated electrons and in situ generated protons from water participate in the former hydrogenation pathway, while the latter requires the photogenerated holes and in situ generated reactive oxygen species to activate the N2H4 to form cis‐N2H2 for further reduction. The present work expands the rational synthesis of ternary sulfide nanostructures and their potential application for solar‐energy‐driven organic transformations.
The body‐centered tetragonal I‐Cu2WS4 nanosheets and primitive tetragonal P‐Cu2WS4 nanoflowers are successfully prepared as highly efficient photocatalysts for hydrogenation of 3‐nitrostyrene by selective activation of the nitro group (─NO2) and carbon–carbon (C═C) double bond, producing 3‐vinylaniline and 3‐ethylnitrobenzene, respectively, with high selectivity and high conversion of 3‐nitrostyrene by the optimal participation of scavengers.
The electronic coupling between a metal electrode and single nano‐entities is of unfading significance which impacts the heterogeneous electron transfer. Herein, we demonstrated a simple optical ...technique for directly imaging the transient interfacial electronic coupling events during electrochemical oxidation of single Ag nanoparticles on Au electrode. The electronic coupling brings out a dramatic dip behavior of bright field imaging traces, and is conductive to cross the energy barrier of oxidation for single silver nanoparticles. This dip behavior is further verified by in situ vis‐transmission spectroscopy, and the heterogeneity of the Au−Ag electronic coupling down to single‐nanoparticle level is uncovered by unifying the morphology and size of individual silver nanoparticles. These results suggest the interfacial electronic coupling facilitates electron transfer of single nanoparticles, and provide important insight into understanding detailed mechanism of nanoelectrochemistry.
During electrochemical oxidation processes, a dip behavior for single Ag nanoparticles on Au electrodes is directly visualized using a monochromatic bright field imaging technique. This observation can be attributed to interfacial Au−Ag electronic coupling interactions, which are manifested as the heterogeneity of electrochemical activity of individual Ag nanoparticles.
The rational synthesis of hierarchical three-dimensional nanostructures with specific compositions, morphologies and functionalities is important for applications in a variety of fields ranging from ...energy conversion and electronics to biotechnology. Here, we report a seeded growth approach for the controlled epitaxial growth of three types of hierarchical one-dimensional (1D)/two-dimensional (2D) nanostructures, where nanorod arrays of II-VI semiconductor CdS or CdSe are grown on the selective facets of hexagonal-shaped nanoplates, either on the two basal facets of the nanoplate, or on one basal facet, or on the two basal facets and six side facets. The seed engineering of 2D hexagonal-shaped nanoplates is the key factor for growth of the three resulting types of 1D/2D nanostructures. The wurtzite- and zinc-blende-type polymorphs of semiconductors are used to determine the facet-selective epitaxial growth of 1D nanorod arrays, resulting in the formation of different hierarchical three-dimensional (3D) nanostructures.
