FABRICATING WELL-DISPERSED NANOSIZED GOLD CATALYST ON TITANATE NANOWIRES SURFACE FOR 4-NITROPHENOL REDUCTION

NANO ◽  
2014 ◽  
Vol 09 (03) ◽  
pp. 1450039 ◽  
Author(s):  
GUANGLIANG CHEN ◽  
FEI XUE ◽  
ZHILI CHEN ◽  
XIAOLEI SI ◽  
XU ZHENG ◽  
...  
Keyword(s):  
Gold Nanoparticles ◽  
Low Temperature ◽  
Catalytic Reduction ◽  
Gold Catalyst ◽  
Face Centered Cubic ◽  
Narrow Size Distribution ◽  
Nitrophenol Reduction ◽  
Titanate Nanowires ◽  
Face Centered ◽  
Organic Capping

In this paper, homogenous gold nanoparticles ( AuNPs ) with a high density and a narrow size distribution were successfully fabricated on titanate nanowires (TNWs) scaffolds in the absence of organic capping agents. An ameliorated low-temperature hydrothermal method was used to prepare the TNWs scaffolds like bird's nest on the Ti substrate, and the nanowires diameter was about 30–80nm. Then, AuNPs were synthesized on the TNWs scaffolds with a deposition–precipitation urea (DPU) method. The TEM and XRD measurements indicated that well-crystallized face-centered cubic (fcc) AuNPs were homogeneously dispersed on TNWs, and AuNPs with average sizes of 2.7 nm and 4 nm were obtained, respectively for the theoretical gold loading 5 wt.% and 8 wt.%. Inspiringly, the 8%- AuNPs /TNWs catalyst could reduce 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) within 210 s, and exhibited better catalytic reduction performance than that of 5%- AuNPs /TNWs.

scholarly journals Microstructure Refinement by Low-Temperature Ausforming in an Fe-Based Metastable High-Entropy Alloy

Metals ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 742
Author(s):  
Motomichi Koyama ◽  
Takeaki Gondo ◽  
Kaneaki Tsuzaki
Keyword(s):  
Low Temperature ◽  
Plastic Anisotropy ◽  
High Entropy Alloy ◽  
Face Centered Cubic ◽  
High Entropy ◽  
Microstructure Refinement ◽  
Hexagonal Close Packed ◽  
Solution Treated Condition ◽  
Solution Treated ◽  
Face Centered

The effects of ausforming in an Fe30Mn10Cr10Co high-entropy alloy on the microstructure, hardness, and plastic anisotropy were investigated. The alloy showed a dual-phase microstructure consisting of face-centered cubic (FCC) austenite and hexagonal close-packed (HCP) martensite in the as-solution-treated condition, and the finish temperature for the reverse transformation was below 200 °C. Therefore, low-temperature ausforming at 200 °C was achieved, which resulted in microstructure refinement and significantly increased the hardness. Furthermore, plasticity anisotropy, a common problem in HCP structures, was suppressed by the ausforming treatment. This, in turn, reduced the scatter of the hardness.

Green Formation of Nano-Hexagon from Nano-Triangle of Gold Nanoparticles Using Palm Oil Fronds Extracts

2019 ◽  
Vol 290 ◽  
pp. 87-92
Author(s):  
Adamu Ibrahim Usman ◽  
Azlan Abdul Aziz ◽  
Osama Abu Noqta
Keyword(s):  
Gold Nanoparticles ◽  
Palm Oil ◽  
Good Control ◽  
Soft Template ◽  
Face Centered Cubic ◽  
Simple Method ◽  
Vis Spectroscopy ◽  
Production Techniques ◽  
Face Centered ◽  
Xrd Patterns

A simple method to synthesized nanoparticles was satisfied by reduction of tetrachloroauric acid in the presence of palm oil fronds extracts as capping and reduced agents. The as-synthesized gold nanoparticles structures have a triangular and hexagonal shape that are of tens of nanometre in size. It was realized that good control shape of nano-hexagonal gold nanoparticles were obtained from nano-triangular gold nanoparticles in the absence of any soft template. The production techniques of the gold nanoparticles were examined by using UV-vis spectroscopy, EFTEM and XRD patterns, which showed peaks at (111), (200), (220), (311) and (222), that described the preferential structure of the AuNPs as face-centered cubic crystal

scholarly journals Exploration of the Antimicrobial and Catalytic Properties of Gold Nanoparticles Greenly Synthesized by Cryptolepis buchanani Roem. and Schult Extract

2020 ◽  
Vol 2020 ◽  
pp. 1-11
Author(s):  
Kamonpan Wongyai ◽  
Phitchayapak Wintachai ◽  
Rasimate Maungchang ◽  
Parawee Rattanakit
Keyword(s):  
Staphylococcus Aureus ◽  
Gold Nanoparticles ◽  
Analytical Techniques ◽  
Average Diameter ◽  
Face Centered Cubic ◽  
Tem Analysis ◽  
X Ray ◽  
Transmission Electron ◽  
Vis Spectroscopy ◽  
Face Centered

A green, simple, and rapid synthesis of gold nanoparticles using plant extract, Cryptolepis buchanani Roem. and Schult, and their applications are first described in this paper. The formation of gold nanoparticles was visually observed by the appearance of a ruby red color, which was further indicated by an absorption peak at 530 nm in UV-Vis spectroscopy. Optimization of reaction parameters for the gold nanoparticles was also investigated. Various analytical techniques were employed as part of the process of characterizing the resulting gold nanoparticles. Fourier transform infrared (FTIR) analysis revealed that the phenol compounds present in the extract were responsible for gold(III) reduction and stabilization of gold nanoparticles. Transmission electron microscopy (TEM) analysis showed that the gold nanoparticles were spherical in shape with an average diameter of 11 nm. Powder X-ray diffraction (XRD) pattern indicated that the green synthesis approach produced highly crystalline, face-centered cubic gold nanoparticles. Energy-dispersive X-ray spectroscopy (EDS) measurements confirmed the presence of elemental gold in the prepared nanoparticles. The negative zeta potential value of gold nanoparticles was found to be -30.28 mV. The green synthesized gold nanoparticles expressed effective antibacterial activity against Staphylococcus aureus, methicillin-resistant Staphylococcus aureus, and Acinetobacter baumannii and exhibited an excellent catalytic property in terms of its reduction ability of methylene blue.

The Bismuth-Barium Oxides

1998 ◽  
Vol 547 ◽  
Author(s):  
K. Müller ◽  
J.K. Meen ◽  
D. Elthon
Keyword(s):  
Solid Solution ◽  
High Temperature ◽  
Low Temperature ◽  
Phase Relations ◽  
The Other ◽  
Face Centered Cubic ◽  
Polymorphic Transformations ◽  
Face Centered ◽  
T Phase

AbstractPhase relations have been determined for the Bi-Ba oxide pseudobinary up to 50 cat % Ba in 1 atm of oxygen at 640°-1000°C. The low-temperature α-Bi2O3 polymorph does not dissolve appreciable BaO. All other phases in the system have significant ranges of solution. The δ-Bi2O3 polymorph, stable from 730°C to 825°C is an end-member of a face-centered cubic solid solution (FCCss) that dissolves up to 2.7 % Ba. Ba-saturated FCCss and Bi-saturated rhombohedral (ß) solid solution (6.3 % Ba) melt at a eutectic at 753 °C. Less Bi is needed to saturate the ß phase at lower temperatures so α-Bi2O3 coexists with a ß phase containing 11.5 % Ba at 646°C.The amount of Ba required to saturate the ß phase depends less strongly on temperature. Ba-saturated ß phase contains 19 % Ba at 700°C. These ß materials are in equilibrium with an oxide near Bi3BaO5.5 that undergoes two polymorphic transformations: low-temperature cubic (<700°C); orthorhombic (700-730°C); high-temperature cubic (Cht). There is a eutectic between the ß and Cht, at 775±6°C. At T<700°C, 26.5 % Ba saturates the latter but it can take in up to 29.5 % Ba (at 812°C). At T<815°C the coexisting phase is BiBaO3. A tetragonal (T) phase forms by reaction of Ch, and BiBaO3 and has ~35% BaO at 815°C. The composition span of T widens as temperature increases. Cht, melts incongruently at 820°C to a liquid and T with 29.8 % Ba. Above that temperature the Bi-saturated and Ba-saturated T phases both become more Ba-rich as temperature is elevated. T melts incongruently to liquid and BiBaO3.The δ-Bi2O3 and ß, both anion conductors, have structures based on that of fluorite. The other oxides have perovskite-like structures. Half of the Bi in BiBaO3 is pentavalent and half is trivalent. The other oxides appear to have all their Bi in the 3+ state.

Synthesis of Monodisperse FePt Nanoparticles at a Low Temperature

2007 ◽  
Vol 124-126 ◽  
pp. 899-902
Author(s):  
Hui Ping Shao ◽  
Yu Qiang Huang ◽  
Hyo Sook Lee ◽  
Yong Jae Suh ◽  
Chong Oh Kim
Keyword(s):  
Thermal Decomposition ◽  
Low Temperature ◽  
Thermal Annealing ◽  
Crystalline Structure ◽  
Fept Nanoparticles ◽  
Face Centered Cubic ◽  
Face Centered

Monodisperse FePt nanoparticles were synthesized by thermal decomposition of Fe(CO)5 and reduction of Pt(acac)2 at low temperature of 160–180 °C by using kerosene as a solvent. The average sizes of the synthesized particles ranged from 2.2 to 4.4 nm. Thermal annealing of the as-prepared FePt particles at 700 °C for 1 h transformed the crystalline structure of the particles from a disordered face-centered cubic to an ordered face-centered tetragonal. This change led to a significant increase in coercivity from 153.37 to 2273.22 Oe and in saturated magnetization from 26.86 to 41.21 emu/g.

LOW TEMPERATURE CREEP AND STRESS RELAXATION FOR PEIERLS BARRIER IN CUBIC METALS

1995 ◽  
Vol 09 (05) ◽  
pp. 285-289 ◽  
Author(s):  
S. A. MAJEED ◽  
N. FAROOQUI ◽  
M. A. AHMED ◽  
S. M. RAZA
Keyword(s):  
Stress Relaxation ◽  
Low Temperature ◽  
Activation Volume ◽  
Face Centered Cubic ◽  
Cubic Metals ◽  
Temperature Creep ◽  
Peierls Barrier ◽  
Face Centered ◽  
Low Temperature Creep ◽  
Creep And Stress Relaxation

The relation for low temperature creep and stress relaxation is developed for Peierls barrier in cubic metals using single barrier stochastic model, with special reference to face-centered cubic crystals. Our conjecture that the strain enhancement is responsible for an increase in activation volume is verified through nondimensionality, i.e. by shear traction number.

scholarly journals Green Synthesis of Gold Nanoparticles from Coprinus comatus, Agaricaceae, and the Effect of Ultraviolet Irradiation on Their Characteristics

2021 ◽  
Vol 18 (8) ◽  
Author(s):  
Ghassan Adnan NAEEM ◽  
Ahmed Saadoun JALOOT ◽  
Mustafa Nadhim OWAID ◽  
Rasim Farraj MUSLIM
Keyword(s):  
Gold Nanoparticles ◽  
Uv Irradiation ◽  
Color Change ◽  
Visible Spectrum ◽  
Face Centered Cubic ◽  
Coprinus Comatus ◽  
Light Yellow ◽  
Uv Visible ◽  
Face Centered ◽  
Nanoscale Range

The present research aims to produce gold nanoparticles (AuNPs) from the aqueous extract of locally isolated mushroom Coprinus comatus from Hit city, Iraq. Its properties were studied using the optical vision, UV-Vis, EDX, XRD, FTIR, AFM, and Zetasizer analyses. The exposure of the colloidal solution of AuNPs to UV radiation was investigated for 1, 2, and 3 h. The results showed the color change of the interaction mixture from light yellow to purple after 25 min. The lambda max of the absorbance reached 530 nm using UV-Visible spectrum as evident in the formation of AuNPs. FTIR spectra revealed the presence of functional groups related to peptides, proteins, flavonoids, monosaccharides, and phenolic compounds, which reduced gold ions. The EDX technique showed that the formed nanoparticles were AuNPs. XRD results showed that AuNPs have a face-centered cubic (fcc) crystal. The UV irradiation at different times led to an increase in the intensity of absorbance and sizes of AuNPs from 17.39 nm before the irradiation and switched to 58.16, 59.13, and 47.35 nm after 1, 2, and 3 h, respectively, but their sizes remained within the nanoscale range (less than 100 nm). In conclusion, the best result was observed after about an hour on the effects of UV irradiation on sizes of AuNPs, which reached smaller nanoparticles compared with times 2 and 3 h.

Sign in / Sign up

Export Citation Format

Share Document