Effect of Different Mineralizers on Luminescence Characteristic of ZnO Crystals by Hydrothermal Method

2013 ◽  
Vol 848 ◽  
pp. 302-306
Author(s):  
Wen Li Zheng ◽  
Wei Yang
Keyword(s):  
Visible Light ◽  
Hydrothermal Method ◽  
Fill Factor ◽  
Crystal Morphology ◽  
Uv Light ◽  
Crystal Defects ◽  
Band Edge ◽  
Luminescence Characteristic ◽  
Amount Of Substance ◽  
Band Edge Transition

A comparative study worked on crystal morphology and luminescence characteristic by hydrothermal method with mineralizer of 3 mol /L KOH, fill factor of 35%, under the condition of three kinds of mineralizers which included 3 mol /L KOH in sample 1, 3 mol /L KOH and 1 mol /L LiOH in sample 2, 3 mol /L KOH and CaO: Zn ( OH) 2 = 2% (amount of substance percentage). Nonpolar ZnO crystals were synthesized by adding proper proportion of CaO or LiOH,the speed of growth along c-axic was weakened obviously. The obtained ZnO crystals exposed more areas on the positive polar face c { 0001}. meanwhile,it exposed negative polar-c {000},positive pyramidal face + p { 101},negative pyramidal face-p {10} and hexagonal faces m {1010}. Only KOH or LiOH auxiliarily added,the emission spectrum was only visible light,no UV light from band edge transition, indicating that the crystal defects luminous center are numerous. A strong UV band emitting from band edge transition was in luminescent spectrumn of the prepared crystals by adding CaO,which indicated a decrease in defects luminous center.

Photo Catalytic Properties of Fe-Modified and Magnetic Nanotitanium Prepared by Hydrothermal Method

2013 ◽  
Vol 743-744 ◽  
pp. 843-848
Author(s):  
Ya Ping Zhang ◽  
Qian Qian Zhi ◽  
Lian Qing Yu ◽  
Kai Tuo Dong ◽  
Ri Shan Liu ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Hydrothermal Method ◽  
Degradation Rate ◽  
Crystal Morphology ◽  
Separation Efficiency ◽  
Uv Light ◽  
Mercury Lamp ◽  
Photo Catalytic Activity ◽  
Reaction Solution ◽  
Fe Addition

In order to improve the separation efficiency and the circular utilization ratio of the catalyst, the Fe-doped nanotitanium and nanotitanium supported on Fe2O3 carrier was prepared by hydrothermal method. The tetra-butyl titanate and ethanol were used as starting materials to prepare nanotitanium. The results of Fe-doped nanotitanium showed that the doping of iron changed the nanotitanium crystal and crystal morphology. No matter UV-light or mercury lamp 577 nm irradiation, the samples with 0.5 mM Fe addition showed the highest photo catalytic activity, with degradation rate of methyl blue above 95%. The structure, photo catalytic activity and magnetic properties analysis showed that the magnetic nanotitanium met the purpose of separation between the catalyst and reaction solution. The photo catalytic activity of nanotitanium supported on Fe2O3 carrier has respond to visible light. With mercury lamp 577 nm as irradiation source, degradation rate of methylene blue light could reach 63.40%.

The Light-Sensitive Character of WO3 Nanorods Synthesized by the Hydrothermal Method

2011 ◽  
Vol 228-229 ◽  
pp. 29-33 ◽  
Author(s):  
Xiao Ming Fu ◽  
Wei Jun Pan ◽  
Zai Zhi Yang
Keyword(s):  
Reaction Time ◽  
Hydrothermal Method ◽  
Crystal Morphology ◽  
Sodium Tungstate ◽  
Ph Value ◽  
Uv Light ◽  
Slenderness Ratio ◽  
Strong Acid ◽  
Potassium Sulphate ◽  
Sensitive Character

Crystalline WO3 nanorods of less than 100 nm in diameter have been successfully synthesized at 240 °C for 72.0 h with pH=1.5 in the system of strong acid with sodium tungstate and potassium sulphate by the hydrothernal method. The morphologies and structures of WO3 rods have been characterized and analyzed by XRD, SEM, TEM and SAED. SEM confirmed that the slenderness ratio of WO3 rods was enlarged with the increase of t the pH value and the reaction time. SAED analysis showed that the crystal morphology of the synthesiezed WO3 nanorods was crystallin. UV-VIS results showed that the absorbent power of UV light for WO3 nanorods enhanced with the increase of their slenderness ratio.

Effects of GaN Thin Layer on InGaN at Electrolyte-Semiconductor Interface for the Application of Photoelectrochemical Water Splitting

2012 ◽  
Vol 1387 ◽  
Author(s):  
Katsushi Fujii ◽  
Kayo Koike ◽  
Mika Atsumi ◽  
Takashi Itoh ◽  
Takenari Goto ◽  
...  
Keyword(s):  
Visible Light ◽  
Water Splitting ◽  
Hydrogen Generation ◽  
Uv Light ◽  
Photocurrent Density ◽  
Crystal Quality ◽  
Band Edge ◽  
Tunneling Effect ◽  
Conduction Band Edge ◽  
Indium Composition

ABSTRACTPhotoelectrochemical properties of nitride semiconductors are paid attention due to their possibilities of water splitting by visible light absorption. However, the photocurrent density of InxGa1-xN, which absorbs visible light, is usually lower than that of GaN, which has larger band-gap and absorbing only UV light. The reasons of this are thought to be the band-edge position at the semiconductor-electrolyte interface and the crystal quality. The conduction band-edge decreases with increasing of indium composition and across the hydrogen generation energy at around the indium composition of 0.2. This means that the hydrogen generation ability decreases with increasing of indium composition. Low crystal quality is obtained because the lower growth temperature of InxGa1-xN than that of GaN to achieve the indium incorporation. In order to improve the photocurrent density, band-edge energy control and quantum tunneling effect are tried using the structure of thin GaN layer on InxGa1-xN here. The effect for the photocurrent densities is also discussed.

Visible-Light Activated [2+2] Photocycloaddition Reaction Enabled Identification of Carbon-Carbon Double Bonds Position Isomerism in Structural Lipidomics

2020 ◽  
Author(s):  
Guifang Feng ◽  
Yanhong Hao ◽  
Liang Wu ◽  
Suming Chen
Keyword(s):  
Visible Light ◽  
Uv Light ◽  
Practical Importance ◽  
Side Reactions ◽  
Potential Health ◽  
Fundamental Interest ◽  
Unsaturated Lipids ◽  
Health Damage ◽  
Global Identification ◽  
Polyunsaturated Lipids

The photocycloaddition of olefins with carbonyls is of fundamental interest and practical importance in C=C bond location in unsaturated lipids. However, the traditional UV light activated [2+2] photocycloaddition reaction suffers side reactions and potential health damage. Here, we reported the first example of visible-light activated [2+2] photocycloaddition of anthraquinone with unsaturated lipids. This reaction showed great capability for locating the C=C bonds in various kinds of monounsaturated and polyunsaturated lipids by combining with tandem mass spectrometry (MS), such as fatty acids, phospholipids and glycerides. Based on this developed reaction, a workflow with liquid chromatography tandem MS method was developed for the global identification of unsaturated lipids in human serum, and 86 of monounsaturated and complicated polyunsaturated lipids were identified with definitive positions of C=C bonds. This approach provides new insights both on the photocycloaddition reactions and the structural lipidomics.

Green Synthesis of ZnO/Dy/NiO Heterostructures for Enhanced Photocatalytic Applications

2020 ◽  
Vol 1 (1) ◽  
pp. 30-36
Author(s):  
Shubha Jayachamarajapura Pranesh ◽  
Diwya Lanka
Keyword(s):  
Visible Light ◽  
Uv Light ◽  
Combustion Method ◽  
Hybrid Nanocomposites ◽  
Synthetic Dyes ◽  
Hybrid Nanostructure ◽  
Wide Range ◽  
Visible Light Active ◽  
Textile Industries ◽  
Photocatalytic Applications

Background: Textile industries discharge harmful synthetic dyes to nearby water sources. These colour effluents should be treated before discharge to reduce the toxicity caused by synthetic colours. Objective: To synthesize visible light active superstructures to reduce water pollution caused by textile industries. Methods: We have successfully synthesized ZnO/Dy/NiO hybrid nanocomposites using waste curd as fuel by a simple combustion method. The obtained material was able to reduce recombination and enhanced the photocatalytic degradation of organic pollutants. The as-synthesized material was characterized by XRD, absorption spectroscopy, FESEM, EDAX, etc. The obtained hybrid nanostructure was used as a photocatalyst for the degradation of methylene blue under sunlight, UV light as well as in dark. Comparative experiments were carried out with a variation of catalytic load, pH, dye concentrations, etc. for a better understanding of the performance of the catalyst at various conditions. Results and Conclusion: The ternary compound shows wide range of absorption by expanding absorption band both in UV and visible regions. ZnO/Dy/NiO hybrid nanocomposites performed well and showed uniqueness in the activity uder visible light.

scholarly journals Real roles of perylene diimides for improving photocatalytic activity

RSC Advances ◽  
2020 ◽  
Vol 10 (39) ◽  
pp. 23024-23037 ◽  
Author(s):  
Fengxia Zhang ◽  
Wenjing Li ◽  
Tianyi Jiang ◽  
Xuemei Li ◽  
Yuanyuan Shao ◽  
...  
Keyword(s):  
Methylene Blue ◽  
Photocatalytic Activity ◽  
Visible Light ◽  
Hydrothermal Method ◽  
Perylene Diimides ◽  
Photodegradation Rate ◽  
Composite Photocatalysts ◽  
Visible Light Driven

Three novel visible-light-driven composite photocatalysts were synthesized by hydrothermal method. The effects of introducing PDIs with different structures into TiO2 were evaluated by assaying the photodegradation rate of methylene blue.

scholarly journals Microwave-Assisted vs. Conventional Hydrothermal Synthesis of MoS2 Nanosheets: Application towards Hydrogen Evolution Reaction

Crystals ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 1040 ◽  
Author(s):  
Getachew Solomon ◽  
Raffaello Mazzaro ◽  
Vittorio Morandi ◽  
Isabella Concina ◽  
Alberto Vomiero
Keyword(s):  
Hydrothermal Synthesis ◽  
Hydrothermal Method ◽  
Hydrogen Evolution ◽  
Hydrogen Evolution Reaction ◽  
Current Density ◽  
Crystal Morphology ◽  
Synthesis Method ◽  
Synthesis Methods ◽  
Mos2 Nanosheets ◽  
Microwave Assisted

Molybdenum sulfide (MoS2) has emerged as a promising catalyst for hydrogen evolution applications. The synthesis method mainly employed is a conventional hydrothermal method. This method requires a longer time compared to other methods such as microwave synthesis methods. There is a lack of comparison of the two synthesis methods in terms of crystal morphology and its electrochemical activities. In this work, MoS2 nanosheets are synthesized using both hydrothermal (HT-MoS2) and advanced microwave methods (MW-MoS2), their crystal morphology, and catalytical efficiency towards hydrogen evolution reaction (HER) were compared. MoS2 nanosheet is obtained using microwave-assisted synthesis in a very short time (30 min) compared to the 24 h hydrothermal synthesis method. Both methods produce thin and aggregated nanosheets. However, the nanosheets synthesized by the microwave method have a less crumpled structure and smoother edges compared to the hydrothermal method. The as-prepared nanosheets are tested and used as a catalyst for hydrogen evolution results in nearly similar electrocatalytic performance. Experimental results showed that: HT-MoS2 displays a current density of 10 mA/cm2 at overpotential (−280 mV) compared to MW-MoS2 which requires −320 mV to produce a similar current density, suggesting that the HT-MoS2 more active towards hydrogen evolutions reaction.

scholarly journals The Spectral Sensitivities of Single Cells in the Median Ocellus of Limulus

1969 ◽  
Vol 54 (5) ◽  
pp. 636-649 ◽  
Author(s):  
John Nolte ◽  
Joel E. Brown
Keyword(s):  
Visible Light ◽  
Spectral Sensitivity ◽  
Uv Light ◽  
Single Cells ◽  
Chromatic Adaptation ◽  
Sensitivity Curve ◽  
Receptor Cells ◽  
Intracellular Microelectrodes ◽  
Median Ocellus ◽  
Spectral Sensitivity Curve

The spectral sensitivities of single Limulus median ocellus photoreceptors have been determined from records of receptor potentials obtained using intracellular microelectrodes. One class of receptors, called UV cells (ultraviolet cells), depolarizes to near-UV light and is maximally sensitive at 360 nm; a Dartnall template fits the spectral sensitivity curve. A second class of receptors, called visible cells, depolarizes to visible light; the spectral sensitivity curve is fit by a Dartnall template with λmax at 530 nm. Dark-adapted UV cells are about 2 log units more sensitive than dark-adapted visible cells. UV cells respond with a small hyperpolarization to visible light and the spectral sensitivity curve for this hyperpolarization peaks at 525–550 nm. Visible cells respond with a small hyperpolarization to UV light, and the spectral sensitivity curve for this response peaks at 350–375 nm. Rarely, a double-peaked (360 and 530 nm) spectral sensitivity curve is obtained; two photopigments are involved, as revealed by chromatic adaptation experiments. Thus there may be a small third class of receptor cells containing two photopigments.

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