Gold nanoclusters reductively deposited on porous silicon: morphology and electronic structures

1998 ◽  
Vol 76 (11) ◽  
pp. 1707-1716 ◽  
Author(s):  
I Coulthard ◽  
S Degen ◽  
Y -J Zhu ◽  
T K Sham
Keyword(s):  
Gold Nanoparticles ◽  
Porous Silicon ◽  
Photoelectron Spectroscopy ◽  
Gold Nanoclusters ◽  
Gold Complex ◽  
X Ray Diffraction ◽  
Complex Ions ◽  
X Ray ◽  
Preparation Conditions ◽  
P Type

Utilizing porous silicon as a reducing agent and a substrate, gold complex ions [AuCl4]- were reduced from aqueous solution to produce nanoparticles of gold upon the surface of porous silicon. Scanning electron microscopy (SEM) was utilized to study the morphology of the porous silicon layers and the deposits of gold nanoparticles. It is found that preparation conditions have a profound effect on the morphology of the deposits, especially on porous silicon prepared from a p-type wafer. The gold nanoparticles, varying from micrometric aggregates of clusters of the order of 10 nm, to a distribution of nearly spherical clusters of the order of 10 nm, to strings of ~10 nm were observed and compared to bulk gold metal using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and X-ray absorption spectroscopy (XAS). These techniques confirm and complement the SEM findings. The potential for this reductive deposition technique is noted.Key words: gold nanostructures, reductive deposition, porous silicon, morphology, X-ray spectroscopy.

Nitrogen-Doping Induced Optical Bandgap Widening of P-Type Cu2O Flms

2009 ◽  
Vol 1217 ◽  
Author(s):  
Yoshitaka Nakano ◽  
Shu Saeki ◽  
Takeshi Morikawa
Keyword(s):  
Photoelectron Spectroscopy ◽  
Structural Changes ◽  
Optical Bandgap ◽  
Bandgap Energy ◽  
X Ray Diffraction ◽  
X Ray ◽  
N Doping ◽  
Hall Effect Measurements ◽  
Optical Bandgap Energy ◽  
P Type

AbstractWe have investigated the effect of N doping into Cu2O films deposited by reactive magnetron sputtering. With increasing N-doping concentration up to 3 at.%, the optical bandgap energy is enlarged from ˜2.1 to ˜2.5 eV with retaining p-type conductivity as determined by optical absorption and Hall-effect measurements. Additionally, photoelectron spectroscopy in air measurements shows an increase in the valence and conduction band shifts with N doping. These experimental results demonstrate possible optical bandgap widening of p-type N-doped Cu2O films, which is a phenomenon that is probably associated with significant structural changes induced by N doping, as suggested from x-ray diffraction measurements.

Size-controlled Synthesis of Gold Nanoparticles by Thermolysis of a Gold(I)-Sulfide Complex in the Presence of Alkylamines

2009 ◽  
Vol 64 (11-12) ◽  
pp. 1305-1311 ◽  
Author(s):  
Mari Yamamoto ◽  
Yukiyasu Kashiwagi ◽  
Masami Nakamoto
Keyword(s):  
Gold Nanoparticles ◽  
Photoelectron Spectroscopy ◽  
Thermal Analyses ◽  
Controlled Synthesis ◽  
X Ray Diffraction ◽  
X Ray ◽  
Alkyl Chains ◽  
Transmission Electron ◽  
Gas Chromatography Mass Spectroscopy ◽  
Size Controlled

A size-controlled synthesis of gold nanoparticles has been developed by the thermolysis of AuCl(SMe2) in the presence of alkylamines at 120 °C. In the procedure, the key intermediate was [Au(NH2R)2]Cl, detected by electrospray ionization (ESI) mass spectrometry. This thermally unstable intermediate was reduced by alkylamines under mild conditions to produce alkylamine-capped gold nanoparticles. The average diameters of the gold nanoparticles could be regulated in a range from 4.3 to 6.1 nm by applying primary alkylamines with alkyl chains of different lengths. Larger gold nanoparticles with diameters from 10 to 22 nm were prepared by a combination of alkylamines and alkylcarboxylic acids with various lengths of the alkyl chains. The gold nanoparticles were characterized by transmission electron microscopy (TEM), UV/Vis absorption spectroscopy, powder X-ray diffraction (PXRD), X-ray photoelectron spectroscopy (XPS), gas chromatography/mass spectroscopy (GC/MS), and thermogravimetric and differencial thermal analyses (TG/DTA)

Preparation of Pd/GO/Cu Electrode and Its Electrochemical Degradation for 2,4-Dichlorophenol

2020 ◽  
Vol 20 (6) ◽  
pp. 3604-3609
Author(s):  
Jian Zhang ◽  
Yuting Jiang ◽  
Bing Wang ◽  
Lanhe Zhang ◽  
Zheng Li ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Water Environment ◽  
Constant Current ◽  
Surface Element ◽  
Impregnation Method ◽  
Electrochemical Degradation ◽  
X Ray Diffraction ◽  
X Ray ◽  
Preparation Conditions ◽  
The Stability

Chlorinated aromatic compounds (CACs) are a class of persistent organic pollutants, which have serious damage to water environment due to their own stable structure. But a good many of CACs were abandoned because of their tremendous yields and wide applications, so it is urgent to find the effective degradation methods for CACs. The electrochemical method is supposed to be a simple, environmentally friendly and effective pathway to degrade CACs. In this paper, a Pd/GO/Cu composite electrode was prepared by a combination of impregnation method and constant current electrodeposition method, which showed good electrochemical degradation efficiency for the 2,4-dichlorophenol. Scanning electron microscopy (SEM), Fourier transform infrared spectroscopy, X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) were used to characterize the surface structure, functional group composition, crystal structure and surface element valence of the electrode. Moreover, the stability of the electrode was investigated, and the preparation conditions of the electrode were optimized.

Peculiarity of Porous Silicon Formed in the Transition Regime

1994 ◽  
Vol 358 ◽  
Author(s):  
S. Lazarouk ◽  
V. Chumash ◽  
E. Fazio ◽  
S. La Monica ◽  
G. Maiello ◽  
...  
Keyword(s):  
Porous Silicon ◽  
Large Range ◽  
Anodic Oxide ◽  
Electrochemical Anodization ◽  
Transition Regime ◽  
X Ray Diffraction ◽  
X Ray ◽  
Silicon Suboxide ◽  
Fourier Transform Ir ◽  
P Type

ABSTRACTElectrochemical anodization in the transition regime, between porous silicon formation region and electropolishing region, of monocrystalline silicon was investigated. Using this process bright and stable photoluminescence could be obtained on a very large range of substrate resistivities: p=12-0.005 Ωcm for p-type silicon and p = 20-0.001 Ωcm for n-type substrates.Photoluminescence spectra, Fourier Transform IR (FTIR) absorbance and X-Ray Diffraction (XRD) measurements are reported. Investigations showed that anodic silicon suboxide was formed on the surface. The porous structure obtained in the transition regime is suggested to consist of silicon crystallites built inside an anodic oxide.

scholarly journals Nanoengineering of Gold Nanoparticles: Green Synthesis, Characterization, and Applications

Crystals ◽  
2019 ◽  
Vol 9 (12) ◽  
pp. 612 ◽  
Author(s):  
Nancy Tepale ◽  
Víctor V. A. Fernández-Escamilla ◽  
Clara Carreon-Alvarez ◽  
Valeria J. González-Coronel ◽  
Adan Luna-Flores ◽  
...  
Keyword(s):  
Gold Nanoparticles ◽  
Green Synthesis ◽  
Photoelectron Spectroscopy ◽  
X Ray Diffraction ◽  
Fundamental Study ◽  
X Ray ◽  
Force Microscopy ◽  
X Ray Scattering ◽  
Atomic Force ◽  
Transmission Electron

The fundamental aspects of the manufacturing of gold nanoparticles (AuNPs) are discussed in this review. In particular, attention is devoted to the development of a simple and versatile method for the preparation of these nanoparticles. Eco-friendly synthetic routes, such as wet chemistry and biosynthesis with the aid of polymers, are of particular interest. Polymers can act as reducing and/or capping agents, or as soft templates leading to hybrid nanomaterials. This methodology allows control of the synthesis and stability of nanomaterials with novel properties. Thus, this review focus on a fundamental study of AuNPs properties and different techniques to characterize them, e.g., Transmission Electron Microscopy (TEM), Atomic Force Microscopy (AFM), UV-Visible spectroscopy, Dynamic Light Scattering (DLS), X-Ray Diffraction (XRD), X-Ray Photoelectron Spectroscopy, Small-angle X-Ray Scattering (SAXS), and rheology. Recently, AuNPs obtained by “green” synthesis have been applied in catalysis, in medicine, and as antibacterials, sensors, among others.

CHEMICALLY DEPOSITED HETEROJUNCTION SOLAR CELLS Pb(1-x)Cd(x)S(n)/Si(p)

2010 ◽  
Vol 09 (06) ◽  
pp. 599-604 ◽  
Author(s):  
OUNISSI ABDELHAMID ◽  
OUDDAI NADIA
Keyword(s):  
Chemical Deposition ◽  
Average Concentration ◽  
Silicon Substrates ◽  
X Ray Diffraction ◽  
X Ray ◽  
Heterojunction Solar Cells ◽  
Glass Substrates ◽  
Preparation Conditions ◽  
P Type ◽  
Concentration Of Impurities

The fimls of Pb (1-x) Cd (x) S have been prepared on glass substrates by chemical method. The optical study of transmission T(λ) and reflexion R(λ) spectra has enabled us to determine the compounds whose gap is close to 1.5 eV. The heterojunction is obtained by the chemical deposition of the Pb (1-x) Cd (x) S films grown on the p-type Silicon substrates (7 Ω cm). The preparation conditions of the ternary compound whose gap is 1.48 eV have been used to achieve the heterojunction Pb (1-x) Cd (x) S - n/Si - p , and we have studied the effect of thermal treatment on the prepared heterojunction. X-ray diffraction has been used to determine the variation of the crystalline parameter, the ratio of cadmium in the compound Pb (1-x) Cd (x) S and the dependence of the gap on the cadmium composition. C–V characteristics were examined to understand the average concentration of impurities in the compound Pb (1-x) Cd (x) S .

scholarly journals MnO2-loaded activated carbon and its adsorption of formaldehyde

BioResources ◽  
2019 ◽  
Vol 14 (3) ◽  
pp. 7193-7212 ◽  
Author(s):  
Liangcai Wang ◽  
Yishuang Wu ◽  
Shasha Liu ◽  
Yimeng Zhang ◽  
Yu Chen ◽  
...  
Keyword(s):  
Activated Carbon ◽  
Photoelectron Spectroscopy ◽  
Infrared Spectrometry ◽  
Adsorption Efficiency ◽  
X Ray Diffraction ◽  
Isothermal Model ◽  
X Ray ◽  
Preparation Conditions ◽  
The Stability ◽  
Coconut Shell Activated Carbon

Coconut shell activated carbon (AC) loaded with MnO2 was tested as an adsorbent for formaldehyde. Preparation conditions of MnO2-loaded AC (MnO2-AC) were optimized. The resulting AC and MnO2-AC were characterized by scanning electron microscopy, Brunauer-Emmet-Teller analysis, X-ray photoelectron spectroscopy, Fourier transform infrared spectrometry, and X-ray diffraction. The results showed that the adsorption efficiency of formaldehyde (3.5 mg/L) by MnO2-AC (concentration of manganese nitrate/sodium carbonate was 0.3 mol/L, impregnation oscillation time of 4 h, calcination temperature and time of 350 C and 4 h, respectively) was 93.1%, which increased by 251% compared to that of the AC. The adsorption equilibrium of MnO2-AC was achieved after 4 h. With increasing dosage of MnO2-AC, the rate of increasing of the adsorption efficiency became more gradual. The adsorption process of the formaldehyde solution with a low concentration fit the Langmuir adsorption isothermal model, where the adsorption capacity was 9.22 mg/g. The stability and regenerability of MnO2-AC were good.

scholarly journals Synthesis of gold nanoparticles using Platycodon grandiflorum extract and its antipathogenic activity under optimal conditions

2020 ◽  
Vol 10 ◽  
pp. 184798042096169
Author(s):  
Periasamy Anbu ◽  
Subash CB Gopinath ◽  
S Jayanthi
Keyword(s):  
Electron Microscopy ◽  
Gold Nanoparticles ◽  
Plant Extracts ◽  
Photoelectron Spectroscopy ◽  
X Ray Diffraction ◽  
X Ray ◽  
Platycodon Grandiflorum ◽  
Transmission Electron ◽  
Flower Plant ◽  
Average Size

Gold nanoparticles have many applications in the biomedical field, mainly for drug delivery, cancer therapy, and detection of pathogenic microorganisms. In this study, gold nanoparticles synthesized using Platycodon grandiflorum (Balloon flower plant) extracts were evaluated for their antibacterial potential. Gold nanoparticles were synthesized at 20–50°C using different volumes of the leaf extract. Biosynthesis of gold nanoparticles was confirmed by ultraviolet–visible spectral absorption at 545 nm by surface plasmon resonance. The morphology and size of the P. grandiflorum gold nanoparticles were further characterized as spherical in shape with an average size of 15 nm in diameter by scanning electron microscopy and transmission electron microscopy. Energy-dispersive X-ray analysis clearly displayed the presence of gold particles. The structural analysis results with face central cubic crystalline nature and elemental composition, including gold, were confirmed by X-ray diffraction and X-ray photoelectron spectroscopy, respectively. In addition, Fourier transform infrared results identified the functional group in P. grandiflorum that is involved in the reduction of metal ions to gold nanoparticles. The synthesized P. grandiflorum gold nanoparticles exhibited efficient antibacterial activity against Escherichia coli (16 mm) and Bacillus subtilis (11 mm). This report confirms the synthesis of gold nanoparticle from balloon flower plant extracts, which can be used as a reducing and stabilizing agent and demonstrates its antibacterial applications.

scholarly journals A Study on the Transition of Copper Oxide by the Incorporation of Nitrogen

Electronics ◽  
2019 ◽  
Vol 8 (10) ◽  
pp. 1099 ◽  
Author(s):  
Song-Yi Ahn ◽  
Kyung Park ◽  
Daehwan Choi ◽  
Jozeph Park ◽  
Yong Joo Kim ◽  
...  
Keyword(s):  
Copper Oxide ◽  
Photoelectron Spectroscopy ◽  
Gas Flow ◽  
Oxide Semiconductor ◽  
X Ray Diffraction ◽  
Nitrogen Gas ◽  
Flow Rates ◽  
X Ray ◽  
Nitrogen Incorporation ◽  
P Type

In the present study, the effects of nitrogen incorporation on the transition of a p-type copper oxide semiconductor are investigated. The properties of sputtered copper oxide and nitrogen-incorporated copper oxide are evaluated and compared at various nitrogen gas flow rates. The results indicate that the addition of nitrogen results in an increased optical bandgap, accompanied by significantly reduced tail states compared to pristine copper oxide. In addition, X-ray diffraction and X-ray photoelectron spectroscopy reveal that the incorporation of nitrogen stimulates the transition from copper (II) oxide to copper (I) oxide.

EFFECT OF ETCHING TIME ON THE CHARACTERISTICS OF LOW RESISTIVITY POROUS Si DEVICES

2013 ◽  
Vol 27 (30) ◽  
pp. 1350217 ◽  
Author(s):  
RAID A. ISMAIL
Keyword(s):  
Porous Silicon ◽  
Photoelectron Spectroscopy ◽  
Crystalline Silicon ◽  
Electrochemical Anodization ◽  
Etching Time ◽  
X Ray ◽  
Force Microscopy ◽  
Low Resistivity ◽  
Time Scanning ◽  
P Type

In this paper, we report the effect of etching time on the morphological, structural and electrical properties of porous silicon ( PSi ) synthesized by electrochemical anodization of low resistivity p-type crystalline silicon at current density of 15 mA/cm2. Atomic force microscopy (AFM) measurements showed that the square root of roughness is increased with etching time. Scanning electron microscopy (SEM) investigations revealed that the microstructure of porous silicon is varying with etching time and pores from nano-size to micro-size were formed. Energy dispersive X-ray (EDX) analysis confirmed that the amount of oxygen increases with etching time. Porosity and thickness estimated gravimetrically showed a dependence on the anodization time. The room temperature dark electrical resistivity of porous silicon has observed to be increased with etching time. X-ray photoelectron spectroscopy (XPS) analysis of synthesized porous silicon has shown peaks of C 1s, Si 2p, O 1s, F 1s and N 1s. Current–voltage (I–V) characteristics of synthesized Al / PSi /c -Si junctions prepared at different etching times are investigated and analyzed. The ideality factor, barrier height and built-in potential of porous silicon junctions were strongly found to be dependent on the etching time.

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