Search

Abstract: Studies on surface plasmon resonance (LSPR) mediated catalytic transformations have focused on quantification of reaction rates and investigation on enhancement mechanisms. However, the establishment of structure‐performance relationships remains limited. For instance, the importance of nanoparticle size remains overlooked, and relatively large nanoparticles (>50 nm in size) are generally employed as catalysts. Herein, we unravel how plasmon decay pathways (absorption and scattering efficiencies) and electric field enhancements as a function of size dictate plasmonic catalytic performances. We employed Ag NPs having 12–50 nm in size as a proof‐of‐concept catalysts, and the LSPR‐mediated oxidation of p‐aminothiophenol to p,p′‐dimercaptoazobenzene as a model reaction. Our data and simulations revealed that the LSPR‐mediated activities displayed a volcano‐type variation with size, which was dependent on the balance among near field enhancements, absorption, and scattering. As this transformation is driven by the charge‐transfer of LSPR‐excited hot‐electrons to adsorbed O2 molecules, the variations in the optical absorption as a function of size represented the dominant contribution to the plasmonic catalytic activities. We believe our results shed important insights over the optimization of physical and chemical parameters in plasmonic nanoparticles in order to maximize plasmonic catalytic activities. [ABSTRACT FROM AUTHOR]

Herein, we report a successful synthesis of porous TiO 2 monoliths decorated with unique nanoplate, nanoprism, and nanopyramid-shaped CdSe particles through a mild selenylation of CdO embedded inside porous TiO 2 monoliths via a hydrothermal method in a very controlled manner. Compared with pure TiO 2 , as-synthesized CdSe/TiO 2 photocatalyst not only enhances light absorption but also leads to a highly efficient charge-carrier separation. Particularly, the nanoplate-shaped 7% CdSe/TiO 2 photocatalyst (molar percentages of CdSe to TiO 2 is 7:100) exhibits an exceptional hydrogen evolution rate up to 3650 μmol h −1 g −1 without resorting to any noble-metal co-catalysts under visible-light irradiation owing to synergistic effects envisaged by a rational material design. Our results may provide a useful strategy to develop a highly-efficient visible-light-driven hydrogen production system via water splitting. [ABSTRACT FROM AUTHOR]

Controlling the synthesis of nanostructured surfaces is essential to tailor the properties of functional materials such as catalysts. We report on the synthesis of nanocavities of 1-2 nm dimension on planar Si-wafers by sacrificial nanotemplating and atomic layer deposition (ALD). It is shown that the process of nanocavity formation can be directly monitored on a monomolecular level through imaging with an atomic force microscope (AFM). In particular, by employing the AFM peak force tapping mode the simultaneous mapping of surface topography and tip-surface adhesion forces is accessible, which is useful for the assignment of topographical features and determining the orientation of the template molecules on the wafer surface. Detailed analysis based on the three-dimensional AFM topography allows for a quantification of the template and nanocavity surface coverage. The results are of importance for a detailed understanding of the processes underlying template-based nanocavity formation on oxide surfaces. [ABSTRACT FROM AUTHOR]

Cobalt carbides (Co 2 C and Co 3 C) nanocomposites exhibit interesting hard magnetic property, controlled synthesis of individual phase facilitates to clarify the magnetism of each, but it is difficult to obtain the single phase. We present a new approach to address this issue via a polyol refluxing process, using cobalt laurate as the precursor. The single phase Co 2 C magnetic nanochains self-assembled by nanoparticles are synthesized. The precursor is the key factor for controlling the growth kinetics of the Co 2 C nanochains. Cobalt, instead of cobalt carbides, is produced if cobalt chloride, acetate and acetylacetonate replace cobalt laurate as the precursor, respectively. The evolution of the growth process has been studied. In the formation of Co 2 C, first fcc-Co produces, then it transforms into Co 2 C by carbon diffusion process, and the produced carbon first exists in disordered state and then a small amount of them transforms into graphite. Saturation magnetization ( Ms ) of Co 2 C nanochains obtained at 300 °C for 20, 60, and 180 min are 27.1, 18.9, and 10.9 emu g −1 , respectively. The decrease of Ms caused by increasing carbon content, and the carbon content are much larger than the stoichiometric ratio value of Co 2 C (9.2 wt%). The Co 2 C nanochains have mesoporous pore of 3.8 nm and the specific surface area of 48.6 m 2  g −1 . [ABSTRACT FROM AUTHOR]

Bi 2 S 3 nanorods anchored over reduced graphene oxide (rGO/Bi 2 S 3 ) were successfully synthesized via a one-pot hydrothermal process, where in-situ generation of Bi 2 S 3 nanorods and reduction of GO occurred simultaneously. Moreover, the controlled synthesis of rGO/Bi 2 S 3 nanocomposite with tunable size was achieved by adjusting the dosage of GO. The nanocomposites were characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy-dispersive X-ray spectrometry (EDX), X-ray diffraction (XRD), Raman spectroscopy and Fourier transform infrared (FTIR) spectroscopy, respectively. Because of the particular construction of as-prepared nanocomposite and the synergistic effect between rGO sheets and Bi 2 S 3 nanorods, the rGO/Bi 2 S 3 film can effectively accelerate electron transport and extend catalytic active sites, leading to the remarkable electrochemical performance for dopamine sensing. The rGO/Bi 2 S 3 -1/GCE sensor exhibited excellent electrocatalytic activity toward the dopamine oxidation with a wide linear range of 0.01–40 μM and a low detection limit of 12.3 nM. Furthermore, the as-prepared sensor could be feasibly applied to detect dopamine in urine samples. Hence, the prepared rGO/Bi 2 S 3 composite is one of the low cost, extremely promising and nontoxicity materials for electrocatalysis and relevant fields. [ABSTRACT FROM AUTHOR]

As a promising structure in enhancing the photo-catalytic performance of the materials, hollow-shell structure still faces the great challenge of constructing an effective architecture for catalytic application. Herein, multi-shelled hollow microspheres of the visible-light photo-catalyst Bi 2 WO 6 with shells up to the triple (BWO-MSH), have been synthesized by using a facile and effective carbonaceous template route. Intriguingly, the photo-catalytic reaction rate constant of BWO-MSH sample is nearly 16 times higher than the Bi 2 WO 6 prepared through solid-state reaction (BWO-SSR). The single-, double-shelled Bi 2 WO 6 microspheres (Broken) could only be synthesized with lower quality (synthesized with many broken species), and their photo-catalytic performance was nearly the same poor as the BWO-SSR sample. Furthermore, multi-shelled hollow microsphere of Bi 2 O 3 /Bi 2 WO 6 (BO/BWO-MSH) composite was also synthesized. The present work not only extends the scope of high-performance complex mixed metal oxides with multi-shelled microstructures, but also brings a good reference to engineer other impressive photo-catalyst. [ABSTRACT FROM AUTHOR]

Magnetic nanoparticles have been of great interest for various biomedical applications due to their controllability in the distance. Monodisperse superparamagnetic CoFe 2 O 4 (CFO) nanoparticles were synthesized by solvothermal method with oleic acid. The oleic acid ligands are exchanged with citric acid to obtain water-dispersible citric acid-coated CA (CFO–CA) nanoparticles. The M–H curve recorded at room temperature shows the superparamagnetic nature of CFO nanoparticles for both oleic- and citric-coated samples. The magnetic heating performance of CFO–CA shows an exciting dependence on the particle size and surface functionality. The hyperthermia efficiency of CFO–CA nanoparticles increases with increasing magnetic field strength and nanoparticle concentration. A specific absorption ratio value of 152.7 W/g obtained in this study is comparable to other investigations, demonstrating a great potential of CFO–CA nanoparticles for hyperthermia-based treatments. This controlled synthesis process can be applied to various functional biomedical nanoparticles to prepare nanoparticles with designed surface moieties for further potential applications. [Display omitted] • Superparamagnetic CoFe 2 O 4 nanoparticles have been solvothermally synthesized. • CoFe 2 O 4 particle size and magnetic property can be controlled by oleic acid coating. • Ligand exchange has been used to replace oleic acid with citric acid for coating. • Citric acid-coated CoFe 2 O 4 nanoparticles show improvements in magnetic heating. [ABSTRACT FROM AUTHOR]

The use of extensive, time-consuming synthesis and the cost of an additional element in synthesis makes difficult the synthesis of photocatalyst active under a broad wavelength range. We propose a synthesis method to obtain ZnO nanoparticles in distinctive morphologies, which lie to several photocatalytic activation conditions. The Zn precursor concentration, solvent, temperature and reaction time altered the ZnO particles morphologies. Although all synthesis parameters modification interferes in ZnO particle morphology, the most pronounced was Zn salt precursor concentration. The synthesis parameter did not interfere in the crystalline wurtzite ZnO phase and the optical characterization, indicating possibilities of ionic defects formations in ZnO lattice. The “3-D flower like” ZnO structure reaches 98% of discoloration under UV illumination and 42% under visible illumination of initial rhodamine-B concentration. The good UV and visible photocatalytic active confirms that with only the modification of synthesis method without any dopant element, ZnO structure is active in large wavelength range. [ABSTRACT FROM AUTHOR]

A highly selective morphology formation of Cu-Ni bimetallic nanocrystals is developed with a solvothermal method, using poly(vinylpyrrolidone) (PVP) as capping agent and aniline as reducing agent in benzyl alcohol. It is shown that temperature is crucial to the controlled synthesis of nanocrystals, and that Cu-Ni nanoparticles evolve from hexagonal nanoplates to nanowires with increasing the concentration of pyrrolidone unit. The synthetic Cu-Ni hexagonal nanoplates and nanowires are well dispersed and have high crystallinity, purity, uniformity of shape and size, and face-centered cubic lattice structure. Furthermore, a mechanism of the formation of Cu-Ni nanocrystals is proposed, and the functions of capping agent, reducing agent, solvent, etc. are discussed. It is also found that both nanoplates and nanowires show better catalytic activities in o -xylene combustion than the conventional catalyst. Especially, the Cu-Ni nanowire catalyst exhibits the most excellent catalytic performance due to the formation of durian-like surface structure. [ABSTRACT FROM AUTHOR]

There is an ongoing debate on the structure of titania supported vanadia used for catalytic partial oxidation reactions as well as for abatement of nitrogen oxide (NO) by ammonia selective catalytic reduction (NH-SCR). To gain further insight into the essential features of the catalyst composition of the surface we introduce a new class of vanadia model catalysts based on monodispersed silica particles as a platform. The evaluation of the influence of different catalyst components (TiO, WO) and different vanadia synthesis approaches (incipient wetness, ion-exchange) is facilitated by the hierarchical structure of the catalysts as well as the controlled synthesis approach. Catalysts tested under industrial ammonia SCR conditions show a strong dependence on the catalyst composition. In particular, the presence of crystalline titania and tungsta leads to a strong increase in NO conversion. Detailed catalyst characterization by X-ray diffraction and by visible Raman, UV Raman, UV-Vis and X-ray photoelectron spectroscopies provides insight into the bulk structure, the surface composition as well as the vanadia surface structure of the catalysts. The potential of UV resonance Raman spectroscopy for structural analysis of vanadia model catalysts for SCR is highlighted. Differences in catalytic activity are discussed in light of the structural results and the available literature. [ABSTRACT FROM AUTHOR]

An AgI dimer capped with labile organometallic diphosphorus ligands [Cp2Mo2(CO)4(η2-P2)] (Cp=C5H5) acts as a highly pre-organized molecular precursor to direct the construction of 1D or 2D, and 3D organometallic-organic hybrid coordination polymers upon reaction with ditopic pyridine-based linkers. The formation of the supramolecular aggregates can be controlled by the stoichiometry of the organic molecules, and the mechanism is supported by DFT calculations. [ABSTRACT FROM AUTHOR]

Copyright of Chinese Journal of Chemical Physics (1674-0068) is the property of American Institute of Physics and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Well defined crystallographic and one dimensional morphological structure of molybdenum oxide were successfully synthesized by adjusting the duration of hydrothermal treatment. The prepared molybdenum oxide was examined through XRD, SEM, FTIR, TEM, BET and electrochemical studies. The XRD patterns illustrate that MoO x prepared by variying the hydrothermal reaction time are in different crystallographic structure of Mo y O x (Mo 8 O 23 and MoO 3 ). SEM studies reveal the different morphological structures ranging from flake like morphology to nanorods. TEM images confirm the excellent nanorod structure. The nanorod structure ensures good cyclic behaviour with maximum capacitance of 1080 F g −1 at a current density of 2 A g −1 . This large capacity of the MoO 3 nanostructures enabled fabrication of symmetric and asymmertic supercapacitor devices. The asymmertic device exhibits a maximum specific capacitance of 145 F g −1 at 2 mV s −1 with highest energy density of 38.6 W h kg −1 at 374.7 W kg −1 power density. [ABSTRACT FROM AUTHOR]

The controlled conversion of biomass is necessary for their efficient utilization. In this work, we report the controlled synthesis of a novel macroscopic three-dimensional hollow reticulate hard carbon by hydrothermal pretreatment and further low temperature (600 °C) pyrolysis method. The carbonization mechanism is presented based on differential thermal analysis, which shows that the hydrothermal pretreatment gets through the reticulate structure by removing flavonoids and the pyrolysis temperature is a key factor for inheriting the unique architecture. Tested against sodium, the hard carbon exhibits good cycling stability, showing capacity retention of 90% after 1000 cycles. The excellent Na-ion storage property is attributed to the interconnected three-dimensional architecture, the abundant O-containing functional groups and the large interlayer spacing. [ABSTRACT FROM AUTHOR]

Commonly, novel morphology can obviously lead to superior performance. Herein, we have firstly synthesized porous FeSe 2 nanomesh arrays grown on titanium foil, which exhibit remarkable performance during hydrogen evolution reaction (HER). Our sample is fabricated via a general wet-chemical process and then one-step calcination. It is worth noting that the FeSe 2 is tightly stuck on the surface of titanium plate, which could result in enhanced stability in the long-time operation for HER. Moreover, the porous structure could provide large specific surface area and probably more active sites for electrolysis. Based on the above advantages, the as-synthesized material shows a low overpotential of 175 mV at 10 mA cm −2 and excellent stability with 4% increase in overpotential under a constant current density of 10 mA cm −2 for 24 h in 0.5 M H 2 SO 4 solution. [ABSTRACT FROM AUTHOR]

Investigating the surface structure, including crystal surface and surface-coating ligands, of nanoparticulate T1 contrast agent may help to understand the T1 relaxation enhancement in vitro and in vivo. This study presents a novel strategy to develop high-performance T1 magnetic resonance imaging (MRI) contrast agents through optimizing the nanocrystal surface and the nanobio interface. Based on the optimized crystal surface, the novel manganese oxide nanocubes (MOCs) show significantly higher surface-to-volume ratio and an approximately threefold higher r1 value compared to traditional manganese oxide nanospheres. Concurrently, transferring MOCs into aqueous media by dopamine derivatization can avoid the oxidation of Mn(II) ions and provide abundant magnetic core. This optimized surface endows MOCs with a high chemical exchange efficiency during T1 relaxation. Of particular significance, a rationally designed pH-induced charge-switchable surfaces can be negatively charged and corona-free in blood and positively charged surface in tumor sites. This unique feature improves the circulation behavior of this intelligent T1 contrast agent in blood and increases cancer cell uptake to achieve accurate detection of solid tumor, holding great potential in aiding early and precise tumor diagnosis. This study provides a novel tool for sophisticated design of high-performance T1 MRI contrast agents in bioimaging applications. [ABSTRACT FROM AUTHOR]

Well-defined poly(2,5-dihexyloxyphenylene-1,4-diyl) (PPP) is successfully synthesized by the Negishi catalyst-transfer polycondensation (NCTP) using dilithium tetra( tert-butyl)zincate ( tBu4ZnLi2). The obtained PPP possesses the number-averaged molecular weight ( Mn) values in the range of 2100-22 000 and the molar-mass dispersity ( ÐM) values in the range of 1.09-1.23. In addition, block copolymers containing PPP and poly(3-hexylthiophene) (P3HT) segments (PPP- b-P3HT) are synthesized to confirm the feasibility of chain extension between the different monomers based on NCTP. [ABSTRACT FROM AUTHOR]

Well-defined poly(2,5-dihexyloxyphenylene-1,4-diyl) (PPP) is successfully synthesized by the Negishi catalyst-transfer polycondensation (NCTP) using dilithium tetra( tert-butyl)zincate ( tBu4ZnLi2). The obtained PPP possesses the number-averaged molecular weight ( Mn) values in the range of 2100-22 000 and the molar-mass dispersity ( ÐM) values in the range of 1.09-1.23. In addition, block copolymers containing PPP and poly(3-hexylthiophene) (P3HT) segments (PPP- b-P3HT) are synthesized to confirm the feasibility of chain extension between the different monomers based on NCTP. [ABSTRACT FROM AUTHOR]

Gold nanoparticles are attractive in catalytic field due to their high activity and selectivity. However, dispersion and sintering resistance have been two of the biggest issues in catalysis for preparation of gold nanoparticles. In this paper, a controlled impregnation method was employed to prepare highly dispersed and thermally stable Au-based catalysts for aerobic oxidation of benzyl alcohol. The size of hydrotalcites (HTs)-supported Au nanoparticles was 2.8 nm at 300 °C of calcination temperature, which was 3.2 nm when calcination temperature was increased to 600 °C. The mechanism of forming metal nanoparticles was proposed. The high dispersion of Au was ascribed to the directing role of Cu and the interaction between Au (and Pt) and Cu. It was proposed that the thermal stability of Au nanoparticles was due to the simultaneous employment of multiple additional effects. The activity of Au nanoparticles was far higher than those prepared by traditional methods. Furthermore, the PtCu elements in Au nanoparticles were homogeneously distributed. In contrast, they were randomly distributed in Au nanoparticles prepared by the traditional method. [ABSTRACT FROM AUTHOR]

Non-neutral layered crystals, another group of two-dimensional (2D) materials that lack a well-defined van der Waals (vdWs) gap, are those that form strong chemical bonds in-plane but display weak out-of-plane electrostatic interactions, exhibiting intriguing properties for the bulk counterpart. However, investigation of the properties of their atomically thin counterpart are very rare presumably due to the absence of efficient ways to achieve large-area high-quality 2D crystals. Here, high-mobility atomically thin Bi2O2Se, a typical non-neutral layered crystal without a standard vdWs gap, was synthesized via a facial chemical vapor deposition (CVD) method, showing excellent controllability for thickness, domain size, nucleation site, and crystal-phase evolution. Atomically thin, large single crystals of Bi2O2Se with lateral size up to 200 μm and thickness down to a bilayer were obtained. Moreover, optical and electrical properties of the CVD-grown 2D Bi2O2Se crystals were investigated, displaying a size-tunable band gap upon thinning and an ultrahigh Hall mobility of >20000 cm² V-1 s-1 at 2 K. Our results on the high-mobility 2D Bi2O2Se semiconductor may activate the synthesis and related fundamental research of other non-neutral 2D materials. [ABSTRACT FROM AUTHOR]

Green synthesis of nanoparticles (NPs) is a major developing field. In this study, we utilised Whitania somnifera leaves as a green source to synthesise platinum (Pt) NPs. Synthesised Pt NPs resulted from controlled synthesis of 12 nm spherical particles. The synthesised Pt NPs were subjected to anti-diabetic applications resulting in a significant decrease in plasma glucose levels after injecting the Pt NPs into streptozotocin-induced diabetic rats. [ABSTRACT FROM AUTHOR]

In this article, ternary oxides NiCo 2 O 4 with morphologies of nanosheets, nanorods and nanoflowers have been synthesized by the thermal treatment of the precursors which were fabricated via a hydrothermal process. The materials were then used as counter electrodes (CEs) in dye-sensitized solar cells (DSSCs). The DSSCs equipped with NiCo 2 O 4 nanoflowers CE achieved excellent power conversion efficiency (PCE) of 8.48%, which is higher than that of counter parts of NiCo 2 O 4 nanosheets (3.57%), NiCo 2 O 4 nanorods (6.84%) and Pt (8.11%) CEs. Transmission electron microscopy image shows that the NiCo 2 O 4 nanoflowers have the best porous 3-dimensional spatial structure. This study offers a self-assembled synthetic route to prepare NiCo 2 O 4 nanoflowers. The unique structure exhibits high efficient performance and excellent catalytic activity, which may open a new window to use ternary oxides for greatly extending potential applications in dye-sensitized solar cells and other related fields. [ABSTRACT FROM AUTHOR]

Graphical abstract Cobalt hollow nanospheres are successfully synthesized by using the solvothermal method. The morphology of the cobalt hollow nanospheres can be regulated by adjusting the original ethylenediamine/ethanol volume ratio, reaction time and temperature. Impressively, the magnetic property study reveals that the coercivity of the as-synthesized cobalt hollow nanospheres is much enhanced compared with that of bulk cobalt materials. Moreover, the as-synthesized cobalt hollow nanospheres, CoPtHS and CoHS-rGO show highly catalytic activities for the hydrogen generation from ammonia borane (AB) hydrolysis. Abstract Size tunable cobalt hollow nanospheres with high catalytic activity for the ammonia borane (AB) hydrolysis have been synthesized by using the solvothermal method. The complexation between Co2+ and ethylenediamine is observed to be critical for the formation of the cobalt hollow nanospherical structure. The morphology of the cobalt hollow nanospheres can be regulated by adjusting the original ethylenediamine/ethanol volume ratio, reaction time and temperature. Impressively, the magnetic property study reveals that the coercivity of the as-synthesized cobalt hollow nanospheres is much enhanced compared with that of bulk cobalt materials. Meanwhile, Co/Pt bimetal hollow nanospheres (CoPtHS) and graphene-cobalt hollow composite nanospheres (CoHS-rGO) have also been explored. In comparison with the cobalt hollow nanospheres, both the CoPtHS and CoHS-rGO show higher catalytic activities and better repeatability for the catalytic hydrogen generation from AB hydrolysis. Moreover, it is noted that these catalysts could be recycled by using the magnetic separation method. [ABSTRACT FROM AUTHOR]

As an emerging ultrathin semiconductor material, Bi 2 O 2 Se has shown outstanding performance in fields of electronics, optoelectronics and ultrafast optics. High performance Bi 2 O 2 Se nanosheets were desperately needed for further foundational research and practical applications. However, their synthesis has not yet been completely developed. In this paper, high quality Bi 2 O 2 Se nanosheets were efficiently obtained by sdjusting synthesis pressure. The uniform nucleation of Bi 2 O 2 Se nanosheets on substrates was achieved, put forward the nucleation mechanism of Bi 2 O 2 Se nanosheets. The near-infrared (NIR) optoelectronic properties of multilayer Bi 2 O 2 Se nanosheets were systematically investigated. Photodetectors were constructed based on Bi 2 O 2 Se nanosheets of different thicknesses and the near-infrared (NIR) photoelectric properties of Bi 2 O 2 Se-based photodetectors with the highest responsivity were systematically investigated. The multilayer Bi 2 O 2 Se nanosheets exhibit sensitive responsivity to the NIR, including high responsivity (∼825 A/W), high external quantum efficiency (∼1.25 × 105%) and high detectivity (6 × 1010Jones). These results suggest that devices based on multilayer Bi 2 O 2 Se nanosheets may have great potential for future applications in ultrafast, high-sensitivity NIR optoelectronic devices. • 1、Uniform and controlled synthesis of Bi 2 O 2 Se nanosheets were achieved by regulating reaction pressure. • 2、The influence mechanism of multilayer Bi 2 O 2 Se nanosheet thickness on electrical properties was put forward and discussed. • 3、Bi 2 O 2 Se-based photodetectors with ultrahigh responsivity (825 A/W) and external quantum effects (1.25 × 105%) were done. [ABSTRACT FROM AUTHOR]

Controlling the growth of small-sized catalysts with more accessible active sites and low cost is of great significance to promote their hydrodesulfurization (HDS) performance. Herein, we have synthesized an efficient ZnNiMoS x /C composite catalyst by using biomass-derived porous carbon as the support. With ZnCl 2 to regulate porous structure, the obtained carbon support presents an enhanced specific surface area (1581.1 m2/g), which promotes the dispersion of ZnNiMoS x catalysts. The ZnNiMoS x on ZnNiMoS x /C-3 shows fewer layers (2–4 layers) and shorter length (about 4–5 nm), indicating more corner and edge active sites. Besides, the addition of Zn species improves the sulfurization degree of ZnNiMoS x and provides more sulfur vacancies for the enhanced HDS performance. The synthesized ZnNiMoS x /C-3 catalyst shows the k HDS value of dibenzothiophene to be 39.42 × 10−7 mol/(g s) and the direct desulfurization selectivity up to 94.5 %. This study provides a new thought for the development of HDS catalysts with cheap biomass-derived materials. [Display omitted] • An efficient ZnNiMoS x /C composite catalyst is synthesized by using biomass-derived porous carbon as the support. • The high specific surface area of the carbon support promotes the dispersion of the ZnNiMoS x active metal catalysts. • ZnNiMoS x /C-3 produces more corner and edge active sites to promote its hydrodesulfurization activity. • The addition of Zn species improves the sulfurization degree of ZnNiMoS x species and provides more sulfur vacancies. • The ZnNiMoS x /C-3 catalyst shows a K HDS value of 39.42 × 10−7 mol/(g s) and a direct desulfurization selectivity of 94.5 %. [ABSTRACT FROM AUTHOR]

Lead halide perovskite nanocrystals (LHP NCs) have rapidly emerged as one of the most promising materials for optical sources, photovoltaics, and sensor fields. The controlled synthesis of LHP NCs with high monodispersity and precise size tunability has been a subject of intensive research in recent years. However, due to their ionic nature, LHP NCs are usually formed instantaneously, and the corresponding nucleation and growth are difficult to monitor and regulated. In this Perspective, we summarize the representative attempts to achieve controlled synthesis of LHP NCs. We first highlight the burst nucleation and rapid growth characteristics of conventional synthesis methods. Afterward, we introduce the scheme of changing the LHP NCs into kinetically dominant, continuously size-tunable synthesis via nucleation-growth decoupling. We also summarize methods to eliminate undesired ripening effects and achieve homogeneous size distribution through rational ligand selection and solvent engineering. We hope this Perspective will facilitate the development of controlled LHP NCs synthesis protocols and advance the understanding of crystal growth fundamentals of perovskite materials.

2D semiconducting transition metal dichalcogenide (TMDCs) possess atomically thin thickness, a dangling-bond-free surface, flexible band structure, and silicon-compatible feature, making them one of the most promising channels for constructing state-of-the-art field-effect transistors in the post-Moore's era. However, the existing 2D semiconducting TMDCs fall short of meeting the industry criteria for practical applications in electronics due to their small domain size and the lack of an effective approach to modulate intrinsic physical properties. Therefore, it is crucial to prepare and dope 2D semiconducting TMDCs single crystals with wafer size. In this review, the up-to-date progress regarding the wafer-scale growth of 2D semiconducting TMDC polycrystalline and single-crystal films is systematically summarized. The domain orientation control of 2D TMDCs and the seamless stitching of unidirectionally aligned 2D islands by means of substrate design are proposed. In addition, the accurate and uniform doping of 2D semiconducting TMDCs and the effect on electronic device performances are also discussed. Finally, the dominating challenges pertaining to the enhancement of the electronic device performances of TMDCs are emphasized, and further development directions are put forward. This review provides a systematic and in-depth summary of high-performance device applications of 2D semiconducting TMDCs., (© 2023 Wiley-VCH GmbH.)

Controlled synthesis of bimetallic catalysts has attracted much attention in heterogeneous catalysis because their catalytic activity depends on the size of nanoparticles and hence the methods of synthesis. In this work, one convenient method was proposed, with an aim to control the size and dispersion of bimetallic nanoparticles. In this method, Cu (or Ni) configurational ion of hydrotalcites was used as directing reagent, which directed the position and dispersion of the final bimetallic nanoparticles by employing the metal interaction between Cu and Au as the driving force. The size, structure and composition of bimetallic nanoparticles were characterized using techniques of X-ray diffraction (XRD), nitrogen physisorption, X-ray photoelectron spectra (XPS) and scanning transmission electron microscopy (STEM). The mean size of bimetallic AuCu nanoparticles was 2.5 nm, which was 1/4 (Step-impregnation) or 1/10 (Co-impregnation) of that prepared by traditional methods. Even if the loading of Au was increased to 10 wt%, the obtained AuCu nanoparticles were still well dispersed. The catalytic activity of AuCu and AuNi nanoparticles in aerobic oxidation of benzyl alcohol was far higher than those prepared by traditional methods. The mechanism of forming bimetallic nanoparticles was investigated. It was found that the dispersion of Cu (or Ni) and the interaction between Cu (or Ni) and Au are two key factors affecting the dispersion of AuCu (or AuNi) nanoparticles. Graphical Abstract: [ABSTRACT FROM AUTHOR]

Graphitic carbon nitride (g-C 3 N 4 ) with high nitrogen content and surface area was synthesized by the thermal condensation of dicyandiamide and urea. This method gave a much higher product yield than the direct thermal decomposition of urea. The prepared g-C 3 N 4 is active for the Knoevenagel condensation of an aldehyde or ketone with methylenic compounds, but the activity depends on the structure of basic nitrogen species. Fourier transform infrared and X-ray photoelectron spectroscopy show that at least four types of nitrogen species are present in g-C 3 N 4 , including primary amines ( NH 2 ), secondary amines ( NH ), tertiary nitrogen (N( C) 3 ), and pyridinic nitrogen (C N C). The amounts and types of these nitrogen species in g-C 3 N 4 are closely related to the urea/dicyandiamide ratio in its precursor mixture. The catalytic activity of these nitrogen species in the inactivated Knoevenagel condensation system decreases in the order of NH 2 > NH > N( C) 3 > C N C, while it is similar for the NH 2 and NH species in the activated reaction system. This trend provides strong evidence for the abstraction of a proton from the methylenic compounds as the rate-determining step. The prepared g-C 3 N 4 is highly stable and reusable in the Knoevenagel condensation reactions. [ABSTRACT FROM AUTHOR]

Monodisperse magnetite nanospheres with hollow interior and porous shell structure were synthesized through one-pot solvothermal process. The chemical conversions of the Fe (III) compounds to generate Fe 3 O 4 simultaneously coupled with the Ostwald ripening process within the magnetite spheres were considered as underlying mechanism for evolution of the Fe 3 O 4 porous/hollow nanostructure. The morphology of Fe 3 O 4 nanoparticles could be controlled by adjusting the conditions of process variables. We investigated their potential in hyperthermia-based treatments, using an alternative magnetic field. Our study revealed that higher applied frequency resulted in the higher heat generation and thus faster temperature growth. The hyperthermia efficiency of the Fe 3 O 4 nanoparticles generally depended on particle structures and magnetic properties. The Fe 3 O 4 porous/hollow nanoparticles also exhibited an excellent heat generation for several continuous cycles of applied field for a long time. [ABSTRACT FROM AUTHOR]

Unprecedented interest has been spurred recently in two-dimensional (2D) layered transition metal dichalcogenides (TMDs) that possess tunable electronic and optical properties. However, synthesis of a wafer-scale TMD thin film with controlled layers and homogeneity remains highly challenging due mainly to the lack of thermodynamic and diffusion knowledge, which can be used to understand and design process conditions, but falls far behind the rapidly growing TMD field. Here, an integrated density functional theory (DFT) and calculation of phase diagram (CALPHAD) modeling approach is employed to provide thermodynamic insight into lateral versus vertical growth of the prototypical 2D material MoS2. Various DFT energies are predicted from the layer-dependent MoS2, 2D flake-size related mono- and bilayer MoS2, to Mo and S migrations with and without graphene and sapphire substrates, thus shedding light on the factors that control lateral versus vertical growth of 2D islands. For example, the monolayer MoS2 flake in a small 2D lateral size is thermodynamically favorable with respect to the bilayer counterpart, indicating the monolayer preference during the initial stage of nucleation; while the bilayer MoS2 flake becomes stable with increasing 2D lateral size. The critical 2D flake-size of phase stability between mono- and bilayer MoS2 is adjustable via the choice of substrate. In terms of DFT energies and CALPHAD modeling, the size dependent pressure-temperature-composition (P-T-x) growth windows are predicted for MoS2, indicating that the formation of MoS2 flake with reduced size appears in the middle but close to the lower T and higher P "Gas + MoS2" phase region. It further suggests that Mo diffusion is a controlling factor for MoS2 growth owing to its extremely low diffusivity compared to that of sulfur. Calculated MoS2 energies, Mo and S diffusivities, and size-dependent P-T-x growth windows are in good accord with available experiments, and the present data provide quantitative insight into the controlled growth of 2D layered MoS2. [ABSTRACT FROM AUTHOR]

The design of new functional materials with excellent hydrogen production activity under visible-light irradiation has critical significance for solving the energy crisis. A well-controlled synthesis strategy is developed to prepare an Au-Pt-CdS hetero-nanostructure, in which each component of Au, Pt, and CdS has direct contact with the other two materials; Pt is on the tips and a CdS layer along the sides of an Au nanotriangle (NT), which exhibits excellent photocatalytic activity for hydrogen production under light irradiation ( λ > 420 nm). The sequential growth and surfactant-dependent deposition produce the three-component Au-Pt-CdS hybrids with the Au NT acting as core while Pt and CdS serve as a co-shell. Due to the presence of the Au NT cores, the Au-Pt-CdS nanostructures possess highly enhanced light-harvesting and strong local-electric-field enhancement. Moreover, the intimate and multi-interface contact generates multiple electron-transfer pathways (Au to CdS, CdS to Pt and Au to Pt) which guide photoexcited electrons to the co-catalyst Pt for an efficient hydrogen reduction reaction. By evaluating the hydrogen production rate when aqueous Na2SO3-Na2S solution is used as sacrificial agent, the Au-Pt-CdS hybrid exhibits excellent photocatalytic activity that is about 2.5 and 1.4 times larger than those of CdS/Pt and Au@CdS/Pt, respectively. [ABSTRACT FROM AUTHOR]

Three-dimensional (3D) hierarchical heterostructures have been widely studied for energy storage because of their amazing synergistic effect. However, a detailed characterization how the branched structure affects the backbone structure during electrochemical cycling, and the specific relationship between the backbone and the branched heterogeneous structure (namely synergistic effect) have been rarely revealed. In addition, the controllable synthesis of this system still remains a great challenge. Herein, we developed a one-step gradient hydrothermal method to obtain a series of 3D hierarchical heterogeneous nanostructures, including V 2 O 5 /NaV 6 O 15 , V 2 O 5 /ZnV 2 O 6 and V 2 O 5 /CoV 2 O 6 , through controlling the sequence of nucleation and growth processes of different structural units in the same precursor. On the basis of time-resolved in situ X-ray diffraction (XRD) characterizations, we clearly elucidated the synergistic effect between the branched and backbone structure. During the synergistic effect, the branched NaV 6 O 15 helps to reduce the potential barrier during lithium-ion insertion/extraction, buffers the impact of crystal-system transformations during the charge/discharge process; the backbone V 2 O 5 is beneficial to increase the charge/discharge capacity, inhibits the self-aggregation of branched NaV 6 O 15 and maintains the stability of 3D structure. Consequently, 3D V 2 O 5 /NaV 6 O 15 hierarchical heterogeneous microspheres exhibit the best electrochemical performance than pure V 2 O 5 and V 2 O 5 /NaV 6 O 15 physical mixture in lithium-ion batteries (LIBs). When tested at a high rate of 5 A g −1 , 92% of the initial capacity can be maintained after 1000 cycles. We believe this method will be in favor of the construction of 3D hierarchical heterostructures and this specific synergistic effect investigated by in situ XRD will be significant for the design of better electrodes. [ABSTRACT FROM AUTHOR]

Organolead halide perovskites (e.g., CH3NH3PbI3) have caught tremendous attention for their excellent optoelectronic properties and applications, especially as the active material for solar cells. Perovskite crystal quality and dimension is crucial for the fabrication of high-performance optoelectronic and photovoltaic devices. Herein the controlled synthesis of organolead halide perovskite CH3NH3PbI3 nanoplatelets on SiO2/Si substrates is investigated via a convenient two-step vapor transport deposition technique. The thickness and size of the perovskite can be well-controlled from few-layers to hundred nanometers by altering the synthesis time and temperature. Raman characterizations reveal that the evolutions of Raman peaks are sensitive to the thickness. Furthermore, from the time-resolved photoluminescence measurements, the best optoelectronic performance of the perovskite platelet is attributed with thickness of ≈30 nm to its dominant longest lifetime (≈4.5 ns) of perovskite excitons, which means lower surface traps or defects. This work supplies an alternative to the synthesis of high-quality organic perovskite and their possible optoelectronic applications with the most suitable materials. [ABSTRACT FROM AUTHOR]

ZnO nanoparticles (NPs) with various morphologies were obtained at low-temperature using an economic and eco-friendly co-precipitation process. X-ray diffraction analysis confirms the formation of pure wurtzite ZnO phase with crystallite size in the 29–32 nm range, while scanning and transmission electron microscopic observations reveal various morphologies (spherical NPs, nanosheets and hexagonal prismatic NPs) as a function of the precursors mixing protocol. The estimated band gap of the as-prepared NPs calculated on the basis of Kubelka-Munk function was found to be lower than the known band gap energy of bulk ZnO (3.21–3.26 eV compared to 3.37 eV) which was attributed to oxygen vacancies. Photoluminescence spectra showed that the as-prepared NPs have dissimilar amount of point defects. The strongest intensity of the visible emission was observed for spherical NPs, which implies an increased fraction of oxygen. This sample also exhibited a higher photocatalytic activity for the degradation of Rhodamine B (RhB) under visible light irradiation. [ABSTRACT FROM AUTHOR]

• In the process of CVD growth, the concentration of reactants in the substrate region was increased by the method of space compression, the number of nucleation was effectively controlled, and larger size (∼50 µm) Bi 2 O 2 Se was obtained. • Based on the influence of different temperature on the growth of Bi 2 O 2 Se, the nucleation and selenization mechanism of Bi 2 O 3 were revealed, and the controllable growth of Bi 2 O 2 Se in a certain thickness range was realized. • A two-end photodetector was constructed based on Bi 2 O 2 Se with high crystallinity. The device exhibits a response of up to 9550A/W under 405 nm laser excitation. Bi 2 O 2 Se has attracted a lot of attention in the field of photodetection due to its ultra-high mobility and tunable band gap. However, the mechanism of controllable preparation of high-quality Bi 2 O 2 Se is unclear and needs further investigation. In this paper, the concentration of reactants in the substrate region was increased by the method of space-compression, the number of nucleation was effectively controlled, and larger size Bi 2 O 2 Se was obtained. And the nucleation and selenylation mechanisms of Bi 2 O 3 were revealed based on the effect of temperatures modificatives growth of Bi 2 O 2 Se. And the controlled growth was achieved in a certain thickness range by increasing the reactant concentration in the substrate region and controlling the nucleation number. Moreover, photodetectors were constructed based on the highly crystalline Bi 2 O 2 Se. The photodetector exhibited a photoresponsivity of up to 9550 A/W under the excitation of 405 nm light and obtained highly stable and recoverable characteristics with multiple laser switches. [ABSTRACT FROM AUTHOR]

Chalcopyrite, wurtzite and zincblende structured CuInS 2 nanoparticles of 2.6–11.4 nm with high quality and strong luminescence were successfully synthesized by decomposing ethylxanthate salts. The effects of ligands and nucleus structures on nanoparticle structures and properties were studied. The nanoparticle structures could be adjusted by controlling the nucleus structures through tuning the injecting sequences of Cu–S and In–S precursors. The nanoparticle structures could also be adjusted to be wurtzite or chalcopyrite by adjusting the capping ligand ratio of tri- n -octylphosphine/oleic acid/oleylamine. An increase in tri- n -octylphosphine ratio would induce the selective growth of chalcopyrite structured CuInS 2 nanoparticles. The mechanisms in CuInS 2 crystal structure selectivity were discussed, which provides an insight into controlled synthesis of other ternary chalcogenides. [ABSTRACT FROM AUTHOR]

Magnetite nanoparticles of controlled shape and dimensions were synthesized using a modified hydrothermal technique. The influence of different synthesis conditions on the shape, size (length and diameter), structure and magnetic properties of the prepared nanoparticles is presented. The mineral phases, the morphologies, size distribution of the resulting magnetic nanoparticles and their magnetic properties were characterized using different characterization methods. We designed magnetite nanoparticles with different morphologies (nanospheres, nanorods, nanocubes and hexagons) and with improved saturation magnetization reaching 90 emu/g. [ABSTRACT FROM AUTHOR]

Magnetic nanoparticles provide a unique nanosystem for various smart therapy applications because of their biocompatibility, their nanostructures which can be prepared controllably to match with the interest of study and, specifically, their responses to an external magnetic field. Interests in utilizing magnetic nanoparticles for biomedical treatments originate from their external controllability of transportation and movement inside biological objects and magnetic heat generation which provide tremendous advantages for targeted drug delivery and controlled drug release as well as magnetic hyperthermia. Recent progress in synthesis and functionalization has led to the formation of various functional magnetic nanoparticles with controlled magnetic properties based on controlling their particle size, shape and composition. In this review, we focus on the synthesis, protection and functionalization of iron oxide-based magnetic nanoparticles in order to control magnetic properties of nanostructured systems. We also highlight the recent advances in the development of multifunctional therapeutic nanosystems combining magnetic nanoparticles and drugs as well as their superior efficacy in biomedical treatments with smart performance by including therapy and modulated drug delivery and release through magnetic heating. [ABSTRACT FROM AUTHOR]

CaWO 4 nanostructures (nanospheres, nanorods and nanoplates) were synthesized by a hydrothermal process. The morphology, size and composition of these nanostructures were characterized by X-ray powder diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM) and X-ray energy dispersive spectroscopy (EDS). Based on the electron microscope observations, the growth of such nanostructures has been proposed as an Ostwald ripening process followed by self-assembly. Furthermore, magnetic measurement of these CaWO 4 nanostructures indicates as-prepared CaWO 4 nanostructures possess obvious room-temperature ferromagnetism, suggesting the potential of CaWO 4 nanostructures in applications. [ABSTRACT FROM AUTHOR]

Carboxy-terminal hyperbranched poly(ester)s offer great potential as platforms for the support of controlled release of actives in the pharmaceutical, cosmetic, agricultural and biomedical fields. Such materials have been prepared from trimethylolpropane and adipic acid and have been fully characterized using chromatographic, spectroscopic and thermal methods. The thermal stability and degradation features of these polymers have been assessed using thermogravimetry and infrared spectroscopy. The degradation characteristics of these materials have been compared to those of similar hydroxyl-terminated polymers. The prominent feature of the degradation of these polymers is decarboxylation, while that for similar polymers containing hydroxyl end groups is ether formation. [ABSTRACT FROM AUTHOR]

Glycerol-derived hyperbranched poly(ester)s offer superior properties for utilization in agriculture, personal care and biomedical areas. These materials are compatible with bio-environments, are generally nontoxic and are biodegradable. When either hydroxyl or carboxyl end-groups are present, they may be conjugated with a wide variety of active agents to provide controlled-release compositions. Glycerol/adipic acid hyperbranched poly(ester)s have been prepared and characterized using chromatographic, spectroscopic and thermal analysis methods. The thermal degradation characteristics of these polymers have been established using thermogravimetry and infrared spectroscopy. The prominent feature for the degradation for polymers with hydroxyl end-groups is cross-linking ether formation while that for polymers with carboxyl end-groups is decarboxylation. [ABSTRACT FROM AUTHOR]

Layered double hydroxide (LDH) nanoparticles have excellent anion-intercalating property, and their potential as theranostic nanovectors is high. However, understanding of the control of the mean particle size (MPS) and achievement of monodispersed particle size distribution (PSD) remains elusive. Herein, with the aid of statistical design of experiments on a model system of Cl − -intercalated (Zn, Al)-LDH, controlled synthesis of single crystalline nanoparticles using the coprecipitation method followed by hydrothermal treatment (HT) was achieved in three steps. First, a 2 4–1 design enabled the identification of influential parameters for MPS (i.e., salt concentration, molar ratio of carbonate to aluminum, solution addition rate, and interaction between salt concentration and stirring rate) and PSD (i.e., salt concentration and stirring rate), as well as the optimum coprecipitation conditions that result in a monodispersed PSD (i.e., low salt concentration and high stirring rate). Second, a preliminary explanation of the HT was suggested and the optimum HT conditions for obtaining ideal Gaussian PSD with chi-squared ( χ 2 ) < 3 were found to be 85 °C for 5 h. Third, using a central composite design, a quantitative MPS model, expressed in terms of the significant factors, was developed and experimentally verified to synthesize nearly monodispersed LDH nanoparticles with MPS ∼200–500 nm. [ABSTRACT FROM AUTHOR]

This study demonstrates the effect of (co)intercalated anion compositions on nanostructure evolution to understand the formation mechanisms of layered double hydroxide (LDH) nanoparticles following coprecipitation and hydrothermal treatments (HT). Initially, the room temperature coprecipitation resulted in amorphous primary nanoparticles that agglomerated at the edges due to low surface charge densities. The reversibility of such agglomeration was determined by the crystalline quality upon HT and consequent surface charge density, which in turn were strongly influenced by the composition of the intercalated anions. Upon crystallization, the agglomerated Zn 2 Al(OH) 6 (NO 3 ) 0.3 (CO 3 ) 0.35 ⋅ x H 2 O primary nanoparticles re-dispersed, but the Zn 2 Al(OH) 6 (NO 3 )⋅ x H 2 O nanoparticles with much lower stability and higher disorder (especially at the edges) exhibited irreversible agglomeration, and transformed into secondary nanoparticles via aggregational growth. Additionally, the stability studies on Zn 2 Al(OH) 6 (NO 3 ) y (CO 3 ) 0.5(1− y ) ⋅ x H 2 O nanoparticles ( y = 0–1) showed that the size difference between the cointercalated anions caused phase separation when 0.9 ⩾ y ⩾ 0.6, leading to bimodal size distributions. Moreover, the coarsening rates were controlled through the cointercalated anion compositions. By gradually varying the ratio of cointercalated NO 3 − to CO 3 2− , monodispersed Zn 2 Al(OH) 6 (NO 3 ) y (CO 3 ) 0.5(1− y ) ⋅ x H 2 O (0.5 ⩾ y ⩾ 0) nanoparticles with systematic variation in the particle size of ∼200–400 nm were obtained after HT at 85 °C for 12 h. [ABSTRACT FROM AUTHOR]