Noble‐metal nanomaterials are attracting increasing research interest due to their promising applications in electrochemical catalysis, for example. Although great efforts have been devoted to the ...size‐, shape‐, and architecture‐controlled synthesis of noble‐metal nanomaterials, their crystal‐phase‐controlled synthesis is still in its infancy. Here, for the first time, this study reports high‐yield synthesis of Au nanorods (NRs) with alternating 4H/face‐centered cubic (fcc) crystal‐phase heterostructures via a one‐pot wet‐chemical method. The coexistence of 4H and fcc phases is relatively stable, and the 4H/fcc Au NRs can serve as templates for crystal‐phase‐controlled epitaxial growth of other metals. As an example, bimetallic 4H/fcc Au@Pd core–shell NRs are synthesized via the epitaxial growth of Pd on 4H/fcc Au NRs. Significantly, the 4H/fcc Au@Pd NRs show superior mass activity toward the ethanol oxidation reaction, i.e., 6.2 and 4.9 times those of commercial Pd black and Pt/C catalysts, respectively. It is believed that this new synthetic strategy can be used to prepare other novel catalysts for various promising applications.
High‐yield crystal‐phase‐heterostructured 4H/fcc Au@Pd core–shell nanorods are successfully synthesized via a one‐pot, facile, wet‐chemical method. By using the 4H/fcc Au nanorod as a template, a 4H/fcc Au@Pd nanorod with epitaxially grown Pd shell is prepared, which exhibits superior electrocatalytic performance toward the ethanol oxidation reaction.
N and S codoping of graphene is realized by a novel approach: covalent functionalization of graphene oxide using 2‐aminothiophenol as a source of both N and S followed by thermal treatment. The ...resulting N‐ and S‐codoped graphene has potential applications in high‐performance lithium‐ion batteries and as a metal‐free catalyst for oxygen reduction reaction.
Transition metal dichalcogenide (TMD) nanomaterials, specially MoS2, are proven to be appealing nanoagents for photothermal cancer therapies. However, the impact of the crystal phase of TMDs on their ...performance in photoacoustic imaging (PAI) and photothermal therapy (PTT) remains unclear. Herein, the preparation of ultrasmall single‐layer MoS2 nanodots with different phases (1T and 2H phase) is reported to explore their phase‐dependent performances as nanoagents for PAI guided PTT in the second near‐infrared (NIR‐II) window. Significantly, the 1T‐MoS2 nanodots give a much higher extinction coefficient (25.6 L g−1 cm−1) at 1064 nm and subsequent photothermal power conversion efficiency (PCE: 43.3%) than that of the 2H‐MoS2 nanodots (extinction coefficient: 5.3 L g−1 cm−1, PCE: 21.3%). Moreover, the 1T‐MoS2 nanodots also give strong PAI signals as compared to negligible signals of 2H‐MoS2 nanodots in the NIR‐II window. After modification with polyvinylpyrrolidone, the 1T‐MoS2 nanodots can be used as a highly efficient agent for PAI guided PTT to effectively ablate cancer cells in vitro and tumors in vivo under 1064 nm laser irradiation. This work proves that the crystal phase plays a key role in determining the performance of nanoagents based on TMD nanomaterials for PAI guided PTT.
Ultrasmall single‐layer 1T‐ and 2H‐phase MoS2 nanodots are prepared to explore their phase‐dependent photoacoustic imaging (PAI) and photothermal therapy (PTT) properties. The polyvinylpyrrolidone‐modified 1T‐MoS2 nanodots can be used as a highly efficient agent for PAI guided PTT to effectively ablate cancer cells in vitro and tumors in vivo under 1064 nm laser irradiation.
Graphene quantum dots (GQDs) with white fluorescence are synthesized by a microwave‐assisted hydrothermal method using graphite as the precursor. A solution‐processed white‐light‐emitting diode ...(WLED) is fabricated using the as‐prepared white fluorescent GQDs (white‐light‐emitting graphene quantum dots, WGQDs) doped 4,4‐bis(carbazol‐9‐yl)biphenyl as the emissive layer. White‐light emission is obtained from the WLED with 10 wt% doping concentration of WGQDs, which shows a luminance of 200 cd m−2 at the applied voltage of 11–14 V. Importantly, an external quantum efficiency of 0.2% is achieved, which is the highest among all the reported WLED based on GQDs or carbon dots. The results demonstrate that WGQDs as a novel phosphor may open up a new avenue to develop the environmentally friendly WLEDs for practical application in solid‐state lighting.
Graphene quantum dots with white fluorescence are synthesized by microwave‐assisted hydrothermal method. A solution‐processed white‐light‐emitting diode (WLED) is developed using white‐light‐emitting graphene quantum dots as a single‐phase phosphor, which may open up a new avenue to develop the environmentally friendly WLEDs toward their practical application in solid‐state lighting.
Black Phosphorus Quantum Dots Zhang, Xiao; Xie, Haiming; Liu, Zhengdong ...
Angewandte Chemie (International ed.),
March 16, 2015, Letnik:
54, Številka:
12
Journal Article
Recenzirano
As a unique two‐dimensional nanomaterial, layered black phosphorus (BP) nanosheets have shown promising applications in electronics. Although mechanical exfoliation was successfully used to prepare ...BP nanosheets, it is still a challenge to produce novel BP nanostructures in high yield. A facile top‐down approach for preparation of black phosphorus quantum dots (BPQDs) in solution is presented. The obtained BPQDs have a lateral size of 4.9±1.6 nm and thickness of 1.9±0.9 nm (ca. 4±2 layers). As a proof‐of‐concept application, by using BPQDs mixed with polyvinylpyrrolidone as the active layer, a flexible memory device was successfully fabricated that exhibits a nonvolatile rewritable memory effect with a high ON/OFF current ratio and good stability.
Black phosphorus quantum dots (BPQDs) with lateral size of 4.9±1.6 nm and thickness of 1.9±0.9 nm (ca. 4±2 layers) are synthesized in solution by a top‐down approach. The mixture of BPQDs and polyvinylpyrrolidone is successfully used as active layer in a flexible memory device with a nonvolatile rewritable memory effect.
Noble multimetallic nanomaterials, if only consisting of Au, Ag, Pt, and Pd, typically adopt the high-symmetry face-centered cubic (fcc) structure. Here for the first time, by using the 4H/fcc Au@Ag ...nanoribbons (NRBs) as seeds, we report the synthesis of 4H/fcc trimetallic Au@PdAg core–shell NRBs via the galvanic reaction method under ambient conditions. Moreover, this strategy can also be used to synthesize 4H/fcc trimetallic Au@PtAg and quatermetallic Au@PtPdAg core–shell NRBs. Impressively, for the first time, these alloy shells, i.e., PdAg, PtAg, and PtPdAg, epitaxially grown on the 4H/fcc Au core with novel 4H hexagonal phase were successfully synthesized. Remarkably, the obtained 4H/fcc Au@PdAg NRBs exhibit excellent electrocatalytic activity toward the hydrogen evolution reaction, which is even quite close to that of the commercial Pt black. We believe that our findings here may provide a novel strategy for the crystal-structure-controlled synthesis of advanced functional noble multimetallic nanomaterials with various promising applications.
Five‐fold‐twinned PtCu nanoframes (NFs) with nanothorns protruding from their edges are synthesized by a facile one‐pot method. Compared to commercial Pt/C catalyst, the obtained highly anisotropic ...five‐fold‐twinned PtCu NFs show enhanced electrocatalytic performance toward the oxygen reduction reaction and methanol oxidation reaction under alkaline conditions.
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.
High-yield preparation of ultrathin two-dimensional (2D) nanosheets is of great importance for the further exploration of their unique properties and promising applications. Herein, for the first ...time, the high-yield and scalable production of ultrathin 2D ternary chalcogenide nanosheets, including Ta2NiS5 and Ta2NiSe5, in solution is achieved by exfoliating their layered microflakes. The size of resulting Ta2NiS5 and Ta2NiS5 nanosheets ranges from tens of nanometers to few micrometers. Importantly, the production yield of single-layer Ta2NiS5 nanosheets is very high, ca. 86%. As a proof-of-concept application, the single-layer Ta2NiS5 is used as a novel fluorescence sensing platform for the detection of DNA with excellent selectivity and high sensitivity (with detection limit of 50 pM). These solution-processable, high-yield, large-amount ternary chalcogenide nanosheets may also have potential applications in electrocatalysis, supercapacitors, and electronic devices.
In this report, we have developed a rapid and versatile ultrasonication enhanced lithium intercalation (ULI) method to prepare single-layer transition metal dichalcogenide nanosheets (TMDC NSs, ...including MoS2, WS2, and TiS2) by using n-butyllithium (n-BuLi).
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