Jian Zuo

Synthesis of FeP2/C nanohybrids and their performance for hydrogen evolution reaction

Phosphorous-rich FeP2/C nanohybrids are synthesized via the pyrolysis of ferrocene (Fe(C5H5)2) and red phosphorus in an evacuated and sealed quartz tube at 500 °C. The nanohybrids contain orthorhombic FeP2 with conical carbon tubes. Based on the calculated electroactive surface area, the performance of the FeP2/C nanohybrids as a novel non-noble metal electrocatalyst for hydrogen evolution reaction (HER) in 0.50 M H2SO4 is investigated. These nanohybrids show good catalytic activity and stability in the acidic medium and might serve as a promising new class of non-noble metal catalysts for practical HER.

Alternative Synthesis of CuFeSe2 Nanocrystals with Magnetic and Photoelectric Properties

Monodisperse CuFeSe2 nanocrystals of high quality have been successfully synthesized for the first time using a hot-solution injection method from the reaction of metallic acetylacetonates with diphenyl diselenide (Ph2Se2) in oleylamine with addition of oleic acid at 255 °C for 90 min. The characterizations of X-ray diffraction, electron microscopy, and compositional analysis reveal that the resulting CuFeSe2 nanocrystals are of tetragonal phase with a stoichiometric composition. The CuFeSe2 nanocrystals exhibit well-defined quasi-cubic shape with an average size of ∼18 nm, and their shape can be tuned from quasi-cubes to quasi-spheres by adjusting the reaction parameters. Magnetic measurement reveals that the as-synthesized CuFeSe2 nanocrystals are ferromagnetic and paramagnetic at 4 and 300 K, respectively. Additionally, the current-voltage (I-V) behavior of the CuFeSe2 nanocrystals suggests that they are promising candidates for application in optoelectronics and solar energy conversion.

A hexane solution deposition of SnS2 films from tetrabutyltin via a solvothermal route at moderate temperature

SnS2 films have been deposited on glass and alumina plate substrates by the reactions between an organotin precursor [tetrabuyltin, (CH2CH2CH2CH3)4Sn] and carbon disulfide in n-hexane at the temperature range 180–200 °C for 10–40 h. The reaction system was oxygen free and applied at a moderate temperature. The films so prepared were characterized by techniques of X-ray diffraction, Scanning electron microscopy, Raman and Mossbauer spectroscopies. The films deposited on glass as well as on alumina plate have an average thickness of 30 μm, but have different rose-like morphologies, which are influenced by both the anisotropic growths of crystals and the different substrate structures. Photoluminescence measurements show that the films have an emission peak at approximately 590 nm.

Controlled hydrothermal synthesis and luminescent properties of Y2WO6:Eu3+ nanophosphors for light-emitting diodes

AbstractIn this paper, Eu3+-doped yttrium tungstate (Y2WO6) nanophosphors with different morphologies have been synthesized by a hydrothermal method with the assistance of cetyltrimethyl ammonium bromide. X-ray diffraction (XRD), scanning electron microscopy, transmission electron microscopy, high-resolution transmission electron microscopy (HRTEM), selected area electron diffraction (SAED), and photoluminescence spectroscopy (PL) were used to characterize the products. The pH value of the starting solution plays a crucial role in the structures and morphologies of the samples. When the precursors synthesized under alkaline condition are annealed at 1100xa0°C in the air, the pure monoclinic Y2WO6 phase can be obtained. The results of HRTEM and SAED are consistent with those of the XRD patterns, confirming the high crystallinity of the products. A detailed study of the optical properties, including the UV–Vis diffuse reflection spectra, the excitation and emission spectra, CIE coordinate, and color purity of Y2WO6:Eu3+ nanophosphors with different doping concentrations, are presented here. The critical distance Rc and energy transfer mechanism for the concentration quenching of Eu3+ ions are discussed in detail. In addition, the decay time and the thermal stability of the samples have been also investigated elaborately. The PL properties of the as-synthesized materials indicate promising applications in UV-pumped red light-emitting diodes.n

Fabrication of amorphous CoMoS4 as a bifunctional electrocatalyst for water splitting under strong alkaline conditions

With the socio economic development, people have paid more and more attention to energy source problems, especially to clean and renewable energy such as hydrogen. It is appealing but still challenging to find or design an appropriate catalyst which is inexpensive and efficient for both the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in the same electrolyte. In this work, we develop a facile synthesis of amorphous defect-rich CoMoS4via a one-step hydrothermal method, and under alkaline conditions; the CoMoS4 electrode can generate a current density of 10 mA cm-2 at the overpotentials of 143 mV for HER and 342 mV for OER in 1.0 M KOH, respectively. A cell voltage of 1.72 V is required to achieve a current density of 10 mA cm-2 with long-term stability in an electrolyzer using the CoMoS4/CC electrode as both the anode and cathode.

Cu2−xSe nanooctahedra: controllable synthesis and optoelectronic properties

Single crystalline copper selenide (Cu2−xSe) nanocrystals (NCs) with well-defined octahedral morphology are successfully synthesized by a colloidal hot-solution injection method from the reaction of anhydrous CuCl with Ph2Se2 under argon flow, in which 1-octadecene (ODE) and oleylamine (OAm) are used as solvent and surfactant, respectively. The Cu2−xSe octahedral nanostructures are characterized by XRD, SEM, TEM, HRTEM, SAED, EDS, FT-IR and XPS and it is found that they are in the cubic phase with high quality. The growth process of the nanostructures is investigated and it is noted that reaction temperature, reaction time and capping surfactant OAm play significant roles in controlling the morphologies of the final products. Meanwhile, the current–voltage (I–V) behavior of the as-prepared octahedral Cu2−xSe nanostructures is explored for the first time and it is found that the Cu2−xSe octahedral nanostructures are promising candidates for application in photodetection and related areas.

Organometallically Anisotropic Growth of Ultralong Sb2Se3 Nanowires with Highly Enhanced Photothermal Response

Ultralong orthorhombic Sb2Se3 nanowires have been successfully fabricated via an alternative facile organometallic synthetic route from the reaction of triphenylantimony(III) with dibenzyldiselenide in oleylamine at 180-240 °C without any other additives. The formation and growth mechanism of the Sb2Se3 nanowires is intensively investigated, and it is found that the anisotropic growth of the nanowires with almost constant diameters is resulted from the synergistic effects of the intrinsic property of the orthorhombic crystal structure and the weak binding assistance of oleylamine, and the length of the nanowires can be elongated easily by increasing reaction time in the synthetic route. Moreover, the photothermal response of the Sb2Se3 nanowires is first evaluated under illumination of UV light (320-390 nm), and it is especially noted that the Sb2Se3 nanowires exhibit highly enhanced photothermal responses (more than two times the intensity) as compared to the bulk Sb2Se3. In addition, the Sb2Se3 nanowires show excellent light-to-heat performance, which is superior to that of the nanostructured titanium dioxide and silicon powder under the same conditions.

Organometallic-route synthesis, controllable growth, mechanism investigation, and surface feature of PbSe nanostructures with tunable shapes.

Lead selenide (PbSe) nanostructures with well-defined star-shaped morphology are successfully fabricated via a facile organometallic synthetic route from the reaction of tetraphenyl lead (Ph4Pb) with triphenylphosphine selenide (Ph3PSe) in dibenzylamine (DBA) with the assistance of oleic acid (OA) and oleylamine (OAm) at 220 °C for 30 min. The structure and shape of the nanocrystals are investigated by techniques of XRD, SEM, TEM, HRTEM, SAED, and EDX, and it is interesting that the obtained PbSe nanostars present Pb-rich features, although the PbSe nanostars are still in typical rock salt phase. Experimental investigations and ATR-FTIR studies demonstrate that the media of DBA, OA, and OAm with an order OA > DAB > OAm play important roles in the growth of the PbSe nanostars with well-defined shapes because the media not only serve as solvents but capping materials. The synergetic effects of the media are also favorable for the growth of PbSe nanocrystals with the well-defined star-shaped morphologies in the current reaction system. Meanwhile, varied PbSe nanostructures with cubic, side-cut cubic, and octahedral shapes can be fabricated by regulating the relevant reaction conditions, and all of these nanostructures prepared in the procedures demonstrate Pb-rich features due to the selective capping effects of the media to the exposed Pb(II) ions. It is confirmed that the specific shape and geometry of the nanostructures can be tuned by controlling the exposed crystal surfaces and/or the corresponding compositions via the variation of reaction conditions in the media.

Organometallic Synthesis, Structure Determination, Shape Evolution, and Formation Mechanism of Hexapod-like Ternary PbSexS1–x Nanostructures with Tunable Compositions

The fabrication of hexapod-like ternary PbSexS1-x nanostructures has been reported via an alternative organometallic route from reaction of Pb(II) salt with triphenylphosphine selenide (Ph3PSe) and dibenzyl disulfide (DBDS) in dibenzylamine (DBA) with addition of oleic acid (OA) at 260 °C. The shape, structure, and composition of the nanostructured hexapods are investigated and determined by techniques of XRD, SEM, TEM, Raman, HRTEM, SAED, XPS, EDX, and HAADF-STEM, and the obtained ternary nanostructured hexapods are of typical rock salt phase with Pb-rich features without phase separation, and their compositions could be systematically regulated by facile variations of reaction parameters. Investigations reveal that the successful fabrication of the ternary hexapods with tunable compositions is resulted from the effective selection of Se and S sources of Ph3PSe and DBDS that have similar reactivity in the current reaction system along with small lattice mismatch between the two end members of PbSe and PbS. Generally, the relations between the composition and lattice parameters for the ternary nanostructures obtained in DBA with varied addition of OA exhibit linear slops that are consistent well with Vegards law. Interestingly, intensive investigations show that the nanostructures are mainly gradiently alloyed nanostructures with somewhat chalcogen-element segregations or disorders rather than homogeneously alloyed solid-state solutions due to kinetic limitation for short reaction time even though thermodynamics is feasible in the system, and also, high concentration of S element in the feedstocks tends to relative high density of disorders in the ternary nanostructures. Based on the revealing of the formation mechanism for the nanostructures with varied microstructures, the ternary PbSexS1-x hexapods can be tuned from gradient alloys with segregations to approximately homogeneous via enlongating reaction time. In addition, the photolysis of the nanostructures to lead oxysulfate and oxyselenate species is evidenced at ambient condition via Raman detection although they are stable at -190 °C.

Structure transformation and remarkable site-distribution modulation of Eu3+ ions in CaMoO4 : Eu3+ nanocrystals under high pressure

High-pressure behaviors of scheelite-type CaMoO4u2006:u2006Eu3+ nanocrystals with an average size of 30 nm have been investigated by using Raman and luminescence spectroscopy at pressures of up to 21 GPa in a diamond anvil cell (DAC). Under the loading of pressure, the softening of the external T(Bg) mode before 10.8 GPa and the appearance of new Raman peaks suggest a phase transformation around this pressure from scheelite to fergusonite structure. When the pressure is released, the scheelite phase recovers due to the small difference in bond strength between scheelite and fergusonite structures. The transformation pressure is slightly enhanced in nanosized CaMoO4u2006:u2006Eu3+ as compared to the bulk due to the difference in surface energy between the two samples of different sizes. Moreover, it is identified that the Eu3+ ions occupy both the bulk and the surface sites in CaMoO4u2006:u2006Eu3+ nanocrystals at ambient pressure by the site-selective excitation, emission and lifetime spectra. As an effective site probe, the red-to-orange luminescence intensity ratio of Eu3+ ions, I(5D0 → 7F2)/I(5D0 → 7F1), is found to exhibit remarkable changes with pressure, which indicates a large variation of the distribution and the local symmetry of Eu3+ ions.