scholarly journals Rate-Limiting Steps of Dye Degradation over Titania-Silica Core-Shell Photocatalysts

Catalysts ◽  
2019 ◽  
Vol 9 (7) ◽  
pp. 583 ◽  
Author(s):  
Ariane Giesriegl ◽  
Jakob Blaschke ◽  
Shaghayegh Naghdi ◽  
Dominik Eder
Keyword(s):  
Dye Degradation ◽  
Sol Gel ◽  
Dye Adsorption ◽  
Thin Layers ◽  
Continuous Change ◽  
Uv Illumination ◽  
Rate Limiting Step ◽  
Sol Gel Process ◽  
Rate Limiting ◽  
Positively Charged

In this work, we employed a step-by-step sol-gel process to controllably deposit ultra-thin layers of SiO2 on anatase nanoparticles in the range between 0 and 1 nm. The deposition was confirmed by TEM, EDX, and ATR-FTIR (e.g., Ti-O-Si band at 960 cm-1). Zeta potential measurements unravelled a continuous change in surface charge density with increasing silica shell thickness. The photocatalysts were evaluated towards adsorption and degradation of positively-charged and negatively-charged dyes (methylene blue, methyl orange) under UV illumination. The growth mechanism follows the Stranski–Krastanov model with three thickness regimes: (a) Flat islands (first step), (b) mono/bilayers (second/third step), and (c) regular thick films (fourth/fifth step). The results suggest different rate limiting processes for these regimes: (a) For the thinnest scenario, acidic triple-phase boundaries (TPBs) increase the activity for both dyes with their accessibility being the rate limiting step; (b) for continuous mono/bilayers, dye adsorption on the negatively-charged SiO2 shells becomes the rate liming step, which leads to a stark increase in activity for the positively-charged MB and a decrease for MO; (c) for thicker shells, the activity decreases for both dyes and is limited by the charge transport through the isolating shells.

High field 1H NMR Studies of Sol-Gel Kinetics

1986 ◽  
Vol 73 ◽  
Author(s):  
Bruce D. Kay ◽  
Roger A. Assink
Keyword(s):  
Equilibrium Distribution ◽  
Sol Gel ◽  
Nmr Studies ◽  
H Nmr ◽  
Rate Limiting Step ◽  
Rate Of Hydrolysis ◽  
Acid Catalyzed ◽  
Product Species ◽  
Rate Limiting ◽  
Kinetics Of

ABSTRACTHigh resolution 1H NMR spectroscopy at high magnetic fields is employed to study the reaction kinetics of the Si(OCH3)4:CH3OH:H2O sol-gel system. Both the overall extent of reaction as a function of time and the equilibrium distribution of species are measured. In acid catalyzed solution, condensation is the rate limiting step while in base catalyzed solution, hydrolysis becomes rate limiting. A kinetic model in which the rate of hydrolysis is assumed to be independent of the adjacent functional groups is presented. This model correctly predicts the distribution of product species during the initial stages of the sol-gel reaction.

Electrical Properties of beta-LixV2O5 Thin Layers Prepared by the Sol-Gel Process

1994 ◽  
Vol 77 (4) ◽  
pp. 891-896 ◽  
Author(s):  
Seung-Young Bae ◽  
Masaru Miyayama ◽  
Hiroaki Yanagida
Keyword(s):  
Electrical Properties ◽  
Sol Gel ◽  
Thin Layers ◽  
Sol Gel Process

Generation of amorphous ceramic capacitor coatings on titanium using a continuous sol-gel process

1995 ◽  
Vol 10 (10) ◽  
pp. 2626-2630 ◽  
Author(s):  
Brian G. Dixon ◽  
Myles A. Walsh ◽  
Peter G. Phillips ◽  
R. Scott Morris
Keyword(s):  
Electrical Properties ◽  
Sol Gel ◽  
Thin Layers ◽  
Amorphous Films ◽  
Zinc Oxides ◽  
Sol Gel Process ◽  
Ceramic Capacitor ◽  
Amorphous Nature ◽  
Titanium Wire ◽  
Computer Controlled

Thin amorphous films of ceramic capacitor materials were successfully deposited using sol-gel chemistry onto titanium wire using a continuous, computer-controlled process. By repeatedly depositing and calcining very thin layers of material, smooth and even coats can be produced. Surface analyses revealed the layered nature of these thin coats, as well as the amorphous nature of the ceramic. The electrical properties of the better coatings, all composed of niobrium, bismuth, and zinc oxides, were then evaluated.

Structure and Properties of Vanadium Pentoxide Gels

1984 ◽  
Vol 32 ◽  
Author(s):  
J. Livage
Keyword(s):  
Sol Gel ◽  
Host Lattice ◽  
Proton Conductors ◽  
Thin Layers ◽  
Structure And Properties ◽  
Fast Proton ◽  
New Developments ◽  
Semiconducting Properties ◽  
Sol Gel Process ◽  
Polycondensation Process

ABSTRACTTransition metal oxide gels can be obtained, through a polycondensation process, by acidification of aqueous solutions. Thin layers can be easily deposited onto a substrate. Their electronic and ionic properties could lead to new developments of the sol-gel process. The semiconducting properties of V2O gels can be used for antistatic coatings or electrical switching devices. These gels exhibit a lamellar structure and can be described as particle hydrates. They are fast proton conductors and could behave as a host lattice for intercalation.

Indentation hardness and scratch tests for thin layers manufactured by sol-gel process

CLEO: 2015 ◽  
2015 ◽  
Author(s):  
H. Piombini ◽  
F. Compoint ◽  
C. Ambard ◽  
K. Vallé ◽  
Ph. Belleville ◽  
...  
Keyword(s):  
Sol Gel ◽  
Thin Layers ◽  
Indentation Hardness ◽  
Sol Gel Process ◽  
Scratch Tests

Tailored Pt/TiO2 Photocatalyst with Controllable Phase Prepared via a Modified Sol–Gel Process for Dye Degradation

2018 ◽  
Vol 18 (3) ◽  
pp. 2235-2240 ◽  
Author(s):  
Bing-Shun Huang ◽  
En-Chin Su ◽  
Yun-Ya Huang ◽  
Hui-Hsin Tseng
Keyword(s):  
Dye Degradation ◽  
Sol Gel ◽  
Tio2 Photocatalyst ◽  
Sol Gel Process

ChemInform Abstract: Electrical Properties of β-LixV2O5 Thin Layers Prepared by the Sol-Gel Process.

ChemInform ◽  
2010 ◽  
Vol 25 (35) ◽  
pp. no-no
Author(s):  
S.-Y. BAE ◽  
M. MIYAYAMA ◽  
H. YANAGIDA
Keyword(s):  
Electrical Properties ◽  
Sol Gel ◽  
Thin Layers ◽  
Sol Gel Process

scholarly journals Synthesis and Electrical Properties of ZnO-ITO and Al-ITO thin Film by Spin Coating Technique Through Sol Gel Process

2018 ◽  
Author(s):  
Hardeli ◽  
Harry Sanjaya ◽  
Rahadian Zainul
Keyword(s):  
Thin Film ◽  
Electrical Properties ◽  
Indium Tin Oxide ◽  
Spin Coating ◽  
Sol Gel ◽  
Thin Layers ◽  
Spin Coating Technique ◽  
Coating Technique ◽  
Sol Gel Process ◽  
Zno Doping

In this research we has investigated synthesis and electrical properties of ITO (Indium Tin Oxide) thin layers doping Aluminum (Al) and ZnO with spin-coating technique through sol-gel process and calcined at ±550 ºC for 1 hour. Effect of Al and ZnO doping on the conductivity of ITO with 0%, 1%, 3% and 5% w/v dopant concentration and the number of coating (4 and 5 layers) has reported. ITO-Al has 2 phases, these are rhombohedral and cubic, the crystal size is 67.31 nm. Meanwhile, ITO-ZnO are rhombohedral, cubic (bixbyite) and hexagonal (wurtzite), with crystallite size value was 67.4 nm. The surface morphology data indicated film thickness was 3.4 µm (ITO-Al) and 0.974 nm (ITO-ZnO). The electrical properties shows that the optimum film in 4 layers coating with the addition of 5% doping value was 17 kΩ/cm2 (ITO-Al) and 5-layered by addition of 5% of doping ZnO (80.800 kΩ/cm2). Meanwhile, ITO-Al thin film with 4 layers coating without doping was 9.331 kΩ / cm2, and for ITO-ZnO (5 layers) coating without doping was 11.796 kΩ/cm2. Al and ZnO doping decrease the electrical conductivity of ITO.

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