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Solution–solid–solid (SSS) nanowires can be catalyzed by superionic Ag2S via ion diffusion. Here, we synthesize ZnS nanowires of the wurtzite crystal structure and heterostructures via a low-temperature growth pathway. Single-crystalline ZnS nanowires were produced by varying reaction time and temperature (120–200 °C) via thermal decomposition of a single-source precursor, Zn(DDTC)2. A phase transformation (zinc blende → wurtzite) was observed during the synthesis with a three-step growth pathway proposed. Temperature-controlled phase transformation facilitates oriented attachment into a 1D nanowire, followed by helical epitaxial and lateral growths during ripening. Additionally, the CdS–ZnS heterostructured nanowires can be obtained after introducing the Cd(DDTC)2 precursor. ZnS nanowires of defined diameters (5–10 nm) are served as backbones to grow heterostructures of ternary semiconductors with multicolor photoluminescence (450–800 nm). Structural and optical characterizations (PL, 2D PLE, and TCSPC) are investigated to confirm origins of broadband emission from multiple lifetimes (0.5–12 ns) for exciton recombination in heterostructures. Our study demonstrates this unique growth pathway for SSS nanowire synthesis under mild, facile, and atmospheric conditions.

Defect engineering is a strategy that has been widely used to design active semiconductor photocatalysts. However, understanding the role of defects, such as oxygen vacancies, in controlling photoc...

Magnetic hydrogel derived from wheat straw cellulose (WSC) and feather protein (FP) was successfully derived from [Bmim]Cl ionic liquids for copper nanoparticles carrier to prepare magnetic hydrogel-Cu (m-WSC/FP-Cu). Morphology, structure and component of m-WSC/FP-Cu were characterized by different techniques (SEM, TEM, XRD, FTIR, VSM, etc.). The activity of m-WSC/FP-Cu were evaluated by employing them as catalysts for the reduction of 2-nitrobenzoic acid (2-NA) to a useful industrial intermediates, 2-aminobenzoic acid (2-ABA). Effect of experimental conditions, including m-WSC/FP-Cu dosage, 2-NA initial concentration, NaBH4 dosage and temperature, were investigated. The m-WSC/FP-Cu exhibited maximum catalytic activity under conditions of 1.00 g m-WSC/FP-Cu, 100 mg/L 2-NA and 0.3 g NaBH4. Besides, higher activity of m-WSC/FP-Cu was obtained at higher temperature. The activity of m-WSC/FP-Cu maintained 99.02% over 5 cycles utilization and 90.60% after 30 days storage, which exhibited excellent recyclability and stability. It is expected that the m-WSC/FP-Cu have the potential for treating organic wastewater cooperated with a catalyst regeneration device.

n-Tetradecylphosphonic acid (TDPA) is an acid and also a source for a strong-binding ligand, n-tetradecylphosphonate (TDPT), for the preparation of the cadmium precursor Cd(DOPT)x(TDPT)1–0.5x (where DOPT = di-n-octylphosphinate). The reaction chemistry of the cadmium precursor and tri-n-octylphosphine telluride (TOPTe) is manipulated to favor the formation of a CdTe solute if the catalytic role of TDPA as an acid is predominant; otherwise the stabilization of the cadmium precursor by TDPT incorporation results in a significant excess of Te in the reaction mixture. These exert opposite consequences on the crystal-phase purity of colloidal CdTe quantum wires (QWs) grown from initial bismuth (Bi) nanoparticles. Primary dissolution of the available CdTe or Te into Bi nanoparticles affords liquid (y ≈ z) or solid (y ≪ z) BixCdyTez catalysts, respectively. The solid catalysts enable the solution–solid–solid growth of nearly phase-pure wurtzite QWs, whereas the liquid catalysts fulfill the solution–liquid–solid ...

Crystal-phase control is one of the most challenging problems in nanowire growth. We demonstrate that, in the solution-phase catalyzed growth of colloidal cadmium telluride (CdTe) quantum wires (QWs), the crystal phase can be controlled by manipulating the reaction chemistry of the Cd precursors and tri-n-octylphosphine telluride (TOPTe) to favor the production of either a CdTe solute or Te, which consequently determines the composition and (liquid or solid) state of the BixCdyTez catalyst nanoparticles. Growth of single-phase (e.g., wurtzite) QWs is achieved only from solid catalysts (y ≪ z) that enable the solution–solid–solid growth of the QWs, whereas the liquid catalysts (y ≈ z) fulfill the solution–liquid–solid growth of the polytypic QWs. Factors that affect the precursor-conversion chemistry are systematically accounted for, which are correlated with a kinetic study of the composition and state of the catalyst nanoparticles to understand the mechanism. This work reveals the role of the precursor-r...

Novel CuS nanoparticles embedded into carbon nanosheets (CuS@CNs) were prepared in situ by applying wheat straw cellulose/feather protein hydrogel beads as templates and were used to photocatalytically activate H2O2 to degrade 2,4-dichlorphenol (2,4-DCP). The photo-Fenton catalytic properties of the nanocomposite catalysts obtained under different synthetic conditions, including different Cu2+ concentrations, S2− concentrations and calcination temperatures, were evaluated. The results showed that CuS@CNs with 0.1 M Cu2+, 0.1 M S2− at 800 °C presented excellent photo-Fenton degradation performance for 2,4-DCP (25 mg/L) in the presence of H2O2 and could remove 90% of 2,4-DCP in 2.5 h. The water quality parameters (pH, Cl−, HCO3−, H2PO4− and SO42−) exhibited different effects on the photocatalytic degradation process. The catalytic activity of the CuS@CNs used in the cycle could be recovered after thermal regeneration. Radical quenching and electron paramagnetic resonance (EPR) experiments confirmed that ·OH species were main active radicals contributing to the degradation of 2,4-DCP. The photocatalytic mechanism of CuS@CNs was also explored by photoelectrochemical (PEC) measurements and UV–vis diffuse reflectance spectroscopy (DRS). Incorporation of carbon nanosheets could significantly improve the separation of photogenerated charge carriers to stimulate pollutant degradation by CuS. Based on the detected intermediates, the degradation pathway of 2,4-DCP in the CuS@CNs/H2O2 reaction system was also proposed.

The development of new nanomaterials for the highly efficient wastewater treatment has been one of the hot scientific researches. Herein, we report a novel 3D Fe3+-doped BiOBr-based magnetic Janus micromotors with superior solar photo-Fenton catalytic activity for organic pollutant degradation. Taking advantage of hydrogen peroxide as reagent and fuel, Fe3+-doped BiOBr based Janus micromotors exhibited extremely high efficiency for methylene blue degradation in a solar photo-Fenton system even at mild pH conditions, which was almost 4 times than BiOBr. The speed of the Janus micromotors could reach 214.7 ± 19.4 μm s−1 in a 5% H2O2 solution. Factors influencing the solar photo-Fenton reaction including Fe3+-doping amount, pH, concentration of H2O2, self-propelled movement as well as mechanical stirring were investigated to clarify the degradation mechanism. Nearly 97% of methylene blue was degraded by Fe0.11Bi0.89OBr/Fe3O4/Mn3O4 Janus micromotors in the presence of 3% H2O2 solution at neutral environment within 50 min. This study provided a new insight into the preparation of Janus micromotors for water purification applications based on solar photo-Fenton reaction.

Biomass-derived hierarchically porous CoFe-LDH (layered double hydroxides)/CeO2 hybrid possessing an inherent peroxidase-like activity was first fabricated employing kapok as bio-template. The CeO2 fibers not only exhibited peroxidase-like activity, but also served as a support and guided the deposition of CoFe-LDH nanosheets on their surface to form a hierarchically porous network. The resultant CoFe-LDH/CeO2 hybrid acted as a peroxidase mimic to catalyze 3,3′,5,5′- tetramethylbenzidine (TMB) with H2O2 to generate a typical blue colored product. Furthermore, CoFe-LDH/CeO2 hybrid displayed superior peroxidase-like catalytic property compared to the pristineCeO2 and CoFe-LDH, which was attributed to the presence of more effective active sites of unique hierarchical-porous architecture and the synergistic effect between CoFe-LDH and CeO2. A facile and sensitive sensing system for H2O2 and glucose determination was successfully proposed, which exhibited a sensitive response to glucose ranging from 0.05–2 mM with a detection limit of 0.015 mM based on the accelerated electron transfer between TMB and H2O2 with the assistance of CoFe-LDH/CeO2. This paper offered a feasible way or the fabrication of materials with hierarchical structure and provided a new insight into seeking novel peroxidase mimics with boosted catalytic activities.

Reaction of n-octylamine-passivated {CdSe[n-octylamine](0.53±0.06)} quantum belts with anhydrous metal carboxylates M(oleate)2 (M = Cd, Zn) results in a rapid exchange of the L-type amine passivation for Z-type M(oleate)2 passivation. The cadmium-carboxylate derivative is determined to have the composition {CdSe[Cd(oleate)2](0.19±0.02)}. The morphologies and crystal structures of the quantum belts are largely unaffected by the exchange processes. Addition of n-octylamine or oleylamine to the M(oleate)2-passivated quantum belts removes M(oleate)2 and restores the L-type amine passivation. Analogous, reversible surface exchanges are also demonstrated for CdS quantum platelets. The absorption and emission spectra of the quantum belts and platelets are reversibly shifted to lower energy by M(oleate)2 passivation vs amine passivation. The largest shift of 140 meV is observed for the Cd(oleate)2-passivated CdSe quantum belts. These shifts are attributed entirely to changes in the strain states in the Zn(oleate)2-passivated nanocrystals, whereas changes in strain states and confinement dimensions contribute roughly equally to the shifts in the Cd(oleate)2-passivated nanocrystals. Addition of Cd(oleate)2, which electronically couples to the nanocrystal lattices, increases the effective thickness of the belts and platelets by approximately a half of a monolayer, thus increasing the confinement dimension.

Colloidal CdTe quantum wires are reported having ensemble photoluminescence efficiencies as high as 25% under low excitation-power densities. High photoluminescence efficiencies are achieved by formation of a monolayer CdS shell on the CdTe quantum wires. Like other semiconductor nanowires, the CdTe quantum wires may contain frequent wurtzite–zinc-blende structural alternations along their lengths. The present results demonstrate that the optical properties, emission-peak shape and photoluminescence efficiencies, are independent of the presence or absence of such structural alternations.

The preparation, isolation, stoichiometric characterization, and dissolution of purified (CdSe)13 nanoclusters are described. We[1] and others[2] recently reported that (CdSe)13 nanoclusters were intermediates in the synthesis of CdSe quantum belts (nanoribbons). We now demonstrate that a lamellar intermediate phase[1] collected from the quantum-belt synthesis is [(CdSe)13(n-octylamine)13], the smallest, discrete, magic-size nanocluster of CdSe that has been observed.[3] Kinetic data show that free, soluble [(CdSe)13(oleylamine)13] nanoclusters are released from the insoluble [(CdSe)13(n-octylamine)13] upon ligand exchange.

Di-n-octylphosphine oxide (DOPO) and di-n-octylphosphinic acid (DOPA), as two of impurities found in commercial tri-n-octylphosphine oxide (TOPO), generate significant differences in the outcomes of CdSe-nanocrystal (NC) syntheses. Using n-tetradecylphosphonic acid (TDPA) as the primary acid additive, quantum dots (QDs) are grown with DOPO added, whereas quantum rods (QRs) are grown in the presence of DOPA. While using oleic acid (OA) as the primary acid additive, QDs are generated and the QDs produced with DOPA exhibit larger sizes and size distributions than those produced with DOPO. 31P NMR analyses of the reaction mixtures reveal that the majority of the DOPO has been converted into DOPA and di-n-octylphosphine (DOP) with DOP being removed via evacuation over the course of Cd-precursor preparation. The origin of the puzzling differences in the shape control of CdSe NCs in the presence of DOPO and DOPA is elucidated to be the small quantity of DOPO present, which liberates DOP during NC synthesis. In t...

An easy shortcut synthesis of thermally stable, near-monodisperse Bi nanoparticles from BiCl(3) and Na[N(SiMe(3))(2)] is described. The diameters of the Bi nanoparticles are controlled in the range of 4-29 nm by varying the amounts of BiCl(3) and Na[N(SiMe(3))(2)] employed. Standard deviations in their diameter distributions are 5-15% of the mean diameters, consistent with near monodispersity. These Bi nanoparticles are shown to be the best currently available catalysts for the solution-liquid-solid (SLS) growth of high-quality CdSe quantum wires.

Tri-n-octylphosphine oxide (TOPO) is the most commonly used solvent for the synthesis of colloidal nanocrystals. Here we show that the use of different batches of commercially obtained TOPO solvent introduces significant variability into the outcomes of CdSe quantum-wire syntheses. This irreproducibility is attributed to varying amounts of phosphorus-containing impurities in the different TOPO batches. We employ (31)P NMR to identify 10 of the common TOPO impurities. Their beneficial, harmful, or negligible effects on quantum-wire growth are determined. The impurity di-n-octylphosphinic acid (DOPA) is found to be the important beneficial TOPO impurity for the reproducible growth of high-quality CdSe quantum wires. DOPA is shown to beneficially modify precursor reactivity through ligand substitution. The other significant TOPO impurities are ranked according to their abilities to similarly influence precursor reactivity. The results are likely of general relevance to most nanocrystal syntheses conducted in TOPO.

Colloidal InP quantum wires are grown by the solution-liquid-solid (SLS) method, and passivated with the traditional quantum dots surfactants 1-hexadecylamine and tri-n-octylphosphine oxide. The size dependence of the band gaps in the wires are determined from the absorption spectra, and compared to other experimental results for InP quantum dots and wires, and to the predictions of theory. The photoluminescence behavior of the wires is also investigated. Efforts to enhance photoluminescence efficiencies through photochemical etching in the presence of HF result only in photochemical thinning or photooxidation, without a significant influence on quantum-wire photoluminescence. However, photooxidation produces residual dot and rod domains within the wires, which are luminescent. The results establish that the quantum-wire band gaps are weakly influenced by the nature of the surface passivation and that colloidal quantum wires have intrinsically low photoluminescence efficiencies.

Palladium catalysts have been used in the hydrodechlorination of perchlorobenzene under mild conditions. PdCl 2 is not very active for this reaction. However, when PdCl 2 is supported on PVP (polyvinyl pyrrolidone), it exhibits a high activity. Pd–Co supported on PVP displays a bimetallic synergic effect and gives higher catalytic activity. The catalytic activity can be increased further by using NaBH 4 to reduce the catalyst instead of H 2 prior to use.

In acidic reaction medium, polymer-supported monometallic palladium catalyst, PVP-PdCl2 [(PVP=poly(N-vinyl-pyrrolidone)], is used to catalyze the hydrogenation of nitrobenzene top-aminophenol and aniline. The addition of a second transition metal compound or a very small amount of 2-mercaptopyrimidine gives rise to an increase in the selectivity forp-aminophenol.

Here, we elucidate a double-lamellar-template pathway for the formation of CdSe quantum belts. The lamellar templates form initially by dissolution of the CdX(2) precursors in the n-octylamine solvent. Exposure of the precursor templates to selenourea at room temperature ultimately affords (CdSe)(13) nanoclusters entrained within the double-lamellar templates. Upon heating, the nanoclusters are transformed to CdSe quantum belts having widths, lengths, and thicknesses that are predetermined by the dimensions within the templates. This template synthesis is responsible for the excellent optical properties exhibited by the quantum belts. We propose that the templated-growth pathway is responsible for the formation of the various flat, colloidal nanocrystals recently discovered, including nanoribbons, nanoplatelets, nanosheets, and nanodisks.

The search for a more efficient production of hydrogen and ethylene glycol from aqueous methanol solution in the presence of ZnS colloid and UV irradiation is reported. The yields of hydrogen and ethylene glycol and the selectivity of ethylene glycol are strongly dependent on the initial pH and the reaction temperature. The selectivity of ethylene glycol can reach 95%. Spin trapping was employed to detect the radical intermediates formed during in situ irradiation of ZnS in aqueous methanol solution. Phenyl- N - tert -butyl nitrone (PBN) can be used as a spin trap. It was confirmed that CH 2 OH is the major radical intermediate in the alkaline reaction system. The coupling of CH 2 OH is the main method of formation of ethylene glycol.

Colloidal GaAs quantum wires with diameters of 5-11 nm and narrow diameter distributions (standard deviation = 12-21% of the mean diameter) are grown by two methods based on the solution-liquid-solid (SLS) mechanism. Resolved excitonic absorption features arising from GaAs quantum wires are detected, allowing extraction of the size-dependent effective band gaps of the wires. The results allow the first systematic comparison of the size dependences of the effective band gaps in corresponding sets of semiconductor quantum wires and quantum wells. The GaAs quantum wire and well band gaps scale according to the prediction of a simple effective-mass-approximation, particle-in-a-box (EMA-PIB) model, which estimates the kinetic confinement energies of electron-hole pairs in quantum nanostructures of different shapes and confinement dimensionalities.

Colloidal InP quantum rods (QRs) having controlled diameters and lengths are grown by the solution-liquid-solid method, from Bi nanoparticles in the presence of hexadecylamine and other conventional quantum dot surfactants. These quantum rods show band-edge photoluminescence after HF photochemical etching. Photoluminescence efficiency is further enhanced after the Bi tips are selectively removed from the QRs by oleic acid etching. The QRs are anisotropically 3D confined, the nature of which is compared to the corresponding isotropic 3D confinement in quantum dots and 2D confinement in quantum wires. The 3D-2D rod-wire transition length is experimentally determined to be 25 nm, which is about 2 times the bulk InP exciton Bohr radius (of approximately 11 nm).

[60]Fullerene mixed peroxides C 6 0 )(O)(OOtBu) 4 exhibit chemo-and regioselective reactions under mild conditions. The epoxy moiety is opened by ferric chloride to form vicinal hydroxy chloride C 6 0 Cl(OH)-(OOtBu) 4 . BF 3 is also effective in opening the epoxy moiety. The 0-0 bond of the fullerene mixed peroxide is cleaved by aluminum chloride to form both [5,6]- and [6,6]-fullerene hemiketals (oxohomo[60]fullerenes). A Hock-type rearrangement is proposed for the formation of the hemiketals, in which a fullerene C-C bond is cleaved. Lewis acids and/or visible light can initiate isomerization of the hemiketal isomers. Single-crystal X-ray analysis and theoretical calculations confirmed the results.