Structural and photocatalytic properties of Cd1-xZnxS nanocrystals via organic solution method

2016 ◽  
Vol 09 (06) ◽  
pp. 1750009 ◽  
Author(s):  
Xiang Liu ◽  
Hanbin Wang ◽  
Dan Shu ◽  
Yang Li ◽  
Xu Chen ◽  
...  
Keyword(s):  
Hydrogen Evolution ◽  
Solution Method ◽  
Organic Chemical ◽  
X Ray Diffraction ◽  
Structural Morphology ◽  
Zinc Blende ◽  
Evolution Experiment ◽  
Xrd Patterns ◽  
Zn Ions ◽  
Zinc Blende Structure

Uniform CdxZn[Formula: see text]S nanocrystals with size between 4[Formula: see text]nm and 9[Formula: see text]nm were fabricated by an organic chemical method. The structural, morphology as well as optical properties of the samples were investigated by X-ray diffraction (XRD), TEM, and UV–Vis absorbance techniques. The XRD patterns of CdxZn[Formula: see text]S nanocrystals indicated that the solid solution possesses cubic zinc-blende structure. By tuning the composition of Zn ions in the alloy, the band gap of CdxZn[Formula: see text]S can be modulated from 2.10[Formula: see text]eV to 3.17[Formula: see text]eV. Photocatalytic hydrogen evolution was investigated under visible-light ([Formula: see text][Formula: see text]nm) irradiation with Na2S/Na2SO3 as the electron donor. It is found that Cd[Formula: see text]Zn[Formula: see text]S nanocrystals have the highest photoactivity with a H2 evolution rate of 1.52[Formula: see text]mmol/h[Formula: see text][Formula: see text][Formula: see text]g. The CdxZn[Formula: see text]S nanoparticles exhibit stable activity in a cycled hydrogen evolution experiment.

Synthesis and Characterization of ZnS: Fe/ZnS Core-Shell Nanocrystals

2011 ◽  
Vol 148-149 ◽  
pp. 900-903
Author(s):  
Li Hua Li ◽  
Yong Jun Gu ◽  
Rui Shi Xie ◽  
Jian Guo Zhu
Keyword(s):  
Chemical Precipitation ◽  
Precipitation Method ◽  
Core Shell ◽  
X Ray Diffraction ◽  
Pl Spectra ◽  
Zinc Blende ◽  
Diffraction Peaks ◽  
Zns Nanocrystals ◽  
Zinc Blende Structure

ZnS:Fe and ZnS:Fe/ZnS core-shell nanocrystals were synthesized by chemical precipitation method. It was found that the ZnS: Fe based nanocrystals possess zinc blende structure. Compared to ZnS: Fe nanocrystals, the intensity of the X-ray diffraction peaks of ZnS: Fe/ZnS nanocrystals reduced and these peaks moved to lower angles. TEM images show that ZnS: Fe based nanocrystals are spheroidal and the average particles size is about 3~4 nm. PL spectra of ZnS: Fe nanocrystals revealed several mission bands, ~406nm, ~444nm, ~416nm, However, PL spectra of ZnS: Fe/ZnS nanocrystals showed several mission bands, ~420nm, ~432nm, ~449nm.

Epitaxial growth of skutterudite (CoSb3) thin films on (001) InSb by pulsed laser deposition

2001 ◽  
Vol 16 (9) ◽  
pp. 2467-2470 ◽  
Author(s):  
J. C. Caylor ◽  
M. S. Sander ◽  
A. M. Stacy ◽  
J. S. Harper ◽  
R. Gronsky ◽  
...  
Keyword(s):  
Pulsed Laser Deposition ◽  
Pulsed Laser ◽  
Laser Deposition ◽  
Heteroepitaxial Growth ◽  
X Ray Diffraction ◽  
Epitaxial Relationship ◽  
X Ray ◽  
Zinc Blende ◽  
Transmission Electron ◽  
Zinc Blende Structure

Heteroepitaxial growth of the cubic skutterudite phase CoSb3 on (001) InSb substrates was achieved by pulsed laser deposition using a substrate temperature of 270 °C and a bulk CoSb3 target with 0.75 at.% excess Sb. An InSb (a0 = 4 0.6478 nm) substrate was chosen for its lattice registry with the antimonide skutterudites (e.g., CoSb3 with a = 0 4 0.9034 nm) on the basis of a presumed 45° rotated relationship with the InSb zinc blende structure. X-ray diffraction and transmission electron microscopy confirmed both the structure of the films and their epitaxial relationship: (001)CoSb3 ∥ (001)InSb; [100]CoSb3 ∥ [110]InSb.

A Study of the Photoluminescence and Reflectivity Spectra of MOCVD Grown MnSe

1994 ◽  
Vol 340 ◽  
Author(s):  
M. Di Blasio ◽  
L. Aigouy ◽  
M. Averous ◽  
J. Calas ◽  
P. Tomasini ◽  
...  
Keyword(s):  
Energy Gap ◽  
Stokes Shift ◽  
Thin Layers ◽  
X Ray Diffraction ◽  
X Ray ◽  
Zinc Blende ◽  
Reflectivity Spectra ◽  
Different Temperatures ◽  
First Time ◽  
Zinc Blende Structure

Photoluminescence (PL) experiments at 2K are performed on MOCVD grown MnSe. The precursors used in the growth stage are methylpentacarbonylmanganese and diethylselenide. Pyrolysis of the percursors is realized inside a gradient reactor under a constant H2 flux, between 280-55°TC. The compound is epitaxially grown on various substrates (Si, InP, GaSb, GaAs, ZnTe/GaAs, etc.). On some of these samples the compound presents a zinc blende structure, while in the other samples rock salt formation has been identified. The first substrate is used because of its interest in Si technology, while the others are used because MnSe can be grown in the zinc blende phase for very thin layers. For the first time x-ray diffraction data has allowed us to determine the lattice constant of zincblende MnSe (aMnse (oct)=5.818Å), confirming the close approximation (a ∼ 5.9Å) used from the Zn1-xMnxSe alloy. These compounds have visible Mn++ transitions at 2.12-5eV; other features are also visible at 2.3-4, 2.7, and 3.0eV. The energy gap transition of tetrahedral thin film layers of MnSe is seen for the first time in PL spectra. A temperature dependant PL study is performed on MnSe in the 2-200K range. Reflectivity experiments are used to attempt to identify the internal manganese transitions. A qualitative PL analysis of the samples grown at different temperatures and on different substrates is provided. A Stokes shift is encountered when the results are compared.

Selective Growth of Gold onto Copper Indium Sulfide Selenide Nanoparticles

2013 ◽  
Vol 68 (5) ◽  
pp. 398-404 ◽  
Author(s):  
Elena Witt ◽  
Jürgen Parisi ◽  
Joanna Kolny-Olesiak
Keyword(s):  
Hybrid Nanostructures ◽  
Indium Sulfide ◽  
X Ray Diffraction ◽  
Gold Nanocrystals ◽  
X Ray ◽  
Copper Indium Disulfide ◽  
Zinc Blende ◽  
Transmission Electron ◽  
Copper Indium ◽  
Zinc Blende Structure

Hybrid nanostructures are interesting materials for numerous applications in chemistry, physics, and biology, due to their novel properties and multiple functionalities. Here, we present a synthesis of metal-semiconductor hybrid nanostructures composed of nontoxic I-III-VI semiconductor nanoparticles and gold. Copper indium sulfide selenide (CuInSSe) nanocrystals with zinc blende structure and trigonal pyramidal shape, capped with dodecanethiol, serve as an original semiconductor part of a new hybrid nanostructure. Metallic gold nanocrystals selectively grow onto vertexes of these CuInSSe pyramids. The hybrid nanostructures were studied by transmission electron microscopy, energy dispersive X-ray analysis, X-ray diffraction, and UV-Vis-absorption spectroscopy, which allowed us conclusions about their growth mechanism. Hybrid nanocrystals are generated by replacement of a sacrificial domain in the CuInSSe part. At the same time, small selenium nanocrystals form that stay attached to the remaining CuInSSe/Au particles. Additionally, we compare the synthesis and properties of CuInSSe-based hybrid nanostructures with those of copper indium disulfide (CuInS2). CuInS2/Au nanostructures grow by a different mechanism (surface growth) and do not show any selectivity.

A new method for analysing peak broadening caused by compositional fluctuation in X-ray diffraction measurements

2001 ◽  
Vol 34 (6) ◽  
pp. 681-690
Author(s):  
Kiichi Nakashima ◽  
Yoshihiro Kawaguchi
Keyword(s):  
New Method ◽  
Theoretical Formula ◽  
X Ray Diffraction ◽  
X Ray ◽  
Compositional Fluctuation ◽  
Zinc Blende ◽  
Difference Variable ◽  
Peak Broadening ◽  
New Criterion ◽  
Zinc Blende Structure

A new method for analysing X-ray peak broadening caused by compositional fluctuation is proposed. The method is applicable to epitaxial layers with diamond or zinc-blende structure on (001) substrates. In the new method, a rescaling procedure with a difference variable ΔAis applied to measured X-ray profiles and the dependence of the profiles on various reflection indiceshklis analysed. The theoretical formula reveals that X-ray peak profiles become independent ofhklafter the rescaling. A new criterion is proposed; an experimental examination based on the criterion makes it possible simply to judge whether or not X-ray peak broadening is caused by compositional fluctuation. The method is verified experimentally and demonstrated by applying it to an InGaAs multilayer sample having artificial compositional fluctuation.

Structural and Optical Investigation of Mn-Doped ZnS Nanocrystals

2005 ◽  
Vol 475-479 ◽  
pp. 1795-1798 ◽  
Author(s):  
W.Q. Peng ◽  
S.C. Qu ◽  
G.W. Cong ◽  
Z.G. Wang
Keyword(s):  
Visible Spectrum ◽  
Optical Investigation ◽  
X Ray Diffraction ◽  
High Concentration ◽  
Zinc Blende ◽  
Order Of Magnitude ◽  
Zns Nanocrystals ◽  
Average Size ◽  
Mn Doped ◽  
Zinc Blende Structure

Using a solution-based chemical method, we have prepared ZnS nanocrystals doped with high concentration of Mn2+. The X-ray diffraction analysis confirmed a zinc blende structure. The average size was about 3 nm. Photoluminescence spectrum showed room temperature emission in the visible spectrum, which consisted of the defect-related emission and the 4 T1-6 A1 emission of Mn2+ ions. Compared with the undoped sample, the luminescence of the ZnS:Mn sample is enhanced by more than an order of magnitude, which indicated that the Mn2+ ions can efficiently boost the luminescence of ZnS nanocrystals.

Structural and Magnetic Hysteresis Properties of Co-Zr Substituted Hexagonal Barium Ferrites

2015 ◽  
Vol 7 (1) ◽  
pp. 1346-1351
Author(s):  
Ch.Gopal Reddy ◽  
Ch. Venkateshwarlu ◽  
P. Vijaya Bhasker Reddy
Keyword(s):  
Magnetic Properties ◽  
Single Phase ◽  
Magnetic Hysteresis ◽  
Grain Morphology ◽  
Hexagonal Structure ◽  
Ion Composition ◽  
X Ray Diffraction ◽  
Ceramic Method ◽  
Barium Ferrites ◽  
Xrd Patterns

Co-Zr substituted M-type hexagonal barium ferrites, with chemical formula BaCoxZrxFe12-2xO19 (where x = 0.0, 0.2, 0.4, 0.6, 0.8 and 1.0), have been synthesized by double sintering ceramic method. The crystallographic properties, grain morphology and magnetic properties of these ferrites have been investigated by X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM) and Vibrating Sample Magnetometer (VSM). The XRD patterns confirm the single phase with hexagonal structure of prepared ferrites. The magnetic properties have been investigated as a function of Co and Zr ion composition at an applied field in the range of 20 KOe. These studies indicate that the saturation magnetization (Ms) in the samples increases initially up to the Co-Zr composition of x=0.6 and decreases thereafter. On the other hand, the coercivity (Hc) and Remanent magnetization (Mr) are found to decrease continuously with increasing Co-Zr content. This property is most useful in permanent magnetic recording. The observed results are explained on the basis of site occupation of Co and Zr ions in the samples.

scholarly journals The Synergistic Effects of Alloying on the Performance and Stability of Co3Mo and Co7Mo6 for the Electrocatalytic Hydrogen Evolution Reaction

Hydrogen ◽  
2020 ◽  
Vol 1 (1) ◽  
pp. 11-21
Author(s):  
Youyi Sun ◽  
Alexey Y. Ganin
Keyword(s):  
Hydrogen Evolution ◽  
Synergistic Effects ◽  
Alkaline Media ◽  
Price Of Stability ◽  
X Ray Diffraction ◽  
Free Standing ◽  
X Ray ◽  
Current Decay ◽  
Earth Abundant ◽  
Current Densities

Metal alloys have become a ubiquitous choice as catalysts for electrochemical hydrogen evolution in alkaline media. However, scarce and expensive Pt remains the key electrocatalyst in acidic electrolytes, making the search for earth-abundant and cheaper alternatives important. Herein, we present a facile and efficient synthetic route towards polycrystalline Co3Mo and Co7Mo6 alloys. The single-phased nature of the alloys is confirmed by X-ray diffraction and electron microscopy. When electrochemically tested, they achieve competitively low overpotentials of 115 mV (Co3Mo) and 160 mV (Co7Mo6) at 10 mA cm−2 in 0.5 M H2SO4, and 120 mV (Co3Mo) and 160 mV (Co7Mo6) at 10 mA cm−2 in 1 M KOH. Both alloys outperform Co and Mo metals, which showed significantly higher overpotentials and lower current densities when tested under identical conditions, confirming the synergistic effect of the alloying. However, the low overpotential in Co3Mo comes at the price of stability. It rapidly becomes inactive when tested under applied potential bias. On the other hand, Co7Mo6 retains the current density over time without evidence of current decay. The findings demonstrate that even in free-standing form and without nanostructuring, polycrystalline bimetallic electrocatalysts could challenge the dominance of Pt in acidic media if ways for improving their stability were found.

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