scholarly journals Photocatalysis and Photoelectrochemical Properties of Tungsten Trioxide Nanostructured Films

2014 ◽  
Vol 2014 ◽  
pp. 1-7 ◽  
Author(s):  
Chin Wei Lai
Keyword(s):  
Tungsten Trioxide ◽  
Critical Role ◽  
Solar Spectrum ◽  
Average Diameter ◽  
Active Surface ◽  
Sodium Sulphate ◽  
Electrochemical Anodization ◽  
Active Surface Area ◽  
Fluoride Ions ◽  
Nanotubular Structure

Tungsten trioxide (WO3) possesses a small band gap energy of 2.4–2.8 eV and is responsive to both ultraviolet and visible light irradiation including strong absorption of the solar spectrum and stable physicochemical properties. Thus, controlled growth of one-dimensional (1D) WO3nanotubular structures with desired length, diameter, and wall thickness has gained significant interest. In the present study, 1D WO3nanotubes were successfully synthesized via electrochemical anodization of tungsten (W) foil in an electrolyte composed of 1 M of sodium sulphate (Na2SO4) and ammonium fluoride (NH4F). The influence of NH4F content on the formation mechanism of anodic WO3nanotubular structure was investigated in detail. An optimization of fluoride ions played a critical role in controlling the chemical dissolution reaction in the interface of W/WO3. Based on the results obtained, a minimum of 0.7 wt% of NH4F content was required for completing transformation from W foil to WO3nanotubular structure with an average diameter of 85 nm and length of 250 nm within 15 min of anodization time. In this case, high aspect ratio of WO3nanotubular structure is preferred because larger active surface area will be provided for better photocatalytic and photoelectrochemical (PEC) reactions.

scholarly journals A Novel Solar Driven Photocatalyst: Well-Aligned Anodic WO3Nanotubes

2013 ◽  
Vol 2013 ◽  
pp. 1-6 ◽  
Author(s):  
Chin Wei Lai ◽  
Sharifah Bee Abd Hamid ◽  
Srimala Sreekantan
Keyword(s):  
Surface Morphology ◽  
Formation Mechanism ◽  
Tungsten Trioxide ◽  
Average Diameter ◽  
Ammonium Fluoride ◽  
Sodium Sulphate ◽  
Electrochemical Anodization ◽  
Methyl Blue ◽  
Photocatalytic Ability ◽  
Nanotubular Structure

Well-aligned anodic tungsten trioxide (WO3) nanotubes were successfully synthesized by anodization of W foil at 40 V in a bath with electrolyte composed of 1 M of sodium sulphate (Na2SO4) and 0.5 wt% ammonium fluoride (NH4F). The effect of electrochemical anodization times on the formation mechanism of anodic WO3nanotubular structure was investigated. It was found that minimum of 15 min is required for completing transformation from W foil to WO3nanotubular structure with an average diameter of 50 nm and length of 500 nm. The photocatalytic ability of the samples was evaluated by degradation of methyl blue (MB) dye. The results indicate that the surface morphology of anodic WO3affected the photocatalytic MB degradation significantly under solar illumination.

scholarly journals Surface Morphology and Growth of Anodic Titania Nanotubes Films: Photoelectrochemical Water Splitting Studies

2015 ◽  
Vol 2015 ◽  
pp. 1-7 ◽  
Author(s):  
Chin Wei Lai
Keyword(s):  
Oxide Layer ◽  
Water Splitting ◽  
Active Surface ◽  
Ammonium Fluoride ◽  
Photocurrent Density ◽  
Photon Absorption ◽  
Electrochemical Anodization ◽  
Nanoporous Structure ◽  
Active Surface Area ◽  
Surface Morphologies

Design and development of one-dimensional nanoarchitecture titania (TiO) assemblies have gained significant scientific interest, which have become the most studied material as they exhibit promising functional properties. In the present study, anodic TiO2films with different surface morphologies can be synthesized in an organic electrolyte of ethylene glycol (EG) by controlling an optimum content of ammonium fluoride (NH4F) using electrochemical anodization technique. Based on the results obtained, well-aligned and bundle-free TiO2nanotube arrays with diameter of 100 nm and length of 8 µm were successfully synthesized in EG electrolyte containing ≈5 wt% of NH4F for 1 h at 60 V. However, formation of nanoporous structure and compact oxide layer would be favored if the content of NH4F was less than 5 wt%. In the photoelectrochemical (PEC) water splitting studies, well-aligned TiO2nanotubular structure exhibited higher photocurrent density of ≈1 mA/cm2with photoconversion efficiency of ≈2% as compared to the nanoporous and compact oxide layer due to the higher active surface area for the photon absorption to generate more photo-induced electrons during photoexcitation stage.

scholarly journals Modification of One-Dimensional TiO2Nanotubes with CaO Dopants for High CO2Adsorption

2014 ◽  
Vol 2014 ◽  
pp. 1-9 ◽  
Author(s):  
Chin Wei Lai
Keyword(s):  
Nitrate Solution ◽  
Calcium Nitrate ◽  
Active Surface ◽  
Electrochemical Anodization ◽  
Active Surface Area ◽  
X Ray Diffraction ◽  
One Dimensional ◽  
X Ray ◽  
Calcium Source ◽  
Field Emission Microscopy

One-dimensional calcium oxide (CaO-) based titanium dioxide (TiO2) nanotubes were successfully synthesized through a rapid electrochemical anodization and chemical wet impregnation techniques. In this study, calcium nitrate solution was used as a calcium source precursor. The reaction time and concentration of calcium source on the formation of CaO-TiO2nanotubes were investigated using field emission microscopy, energy dispersion X-ray spectroscopy, and X-ray diffraction. The adsorption capacity of CO2was determined by thermal gravimetric analyzer. A maximum of 4.45 mmol/g was achieved from the CaO-TiO2nanotubes (6.64 at% of Ca). The finding was attributed to the higher active surface area for CaO to adsorb more CO2gas and then formed CaCO3compound during cyclic carbonation-calcination reaction.

scholarly journals Anodic CaO-TiO2Nanotubes Composite Film for Low Temperature CO2Adsorption

2014 ◽  
Vol 2014 ◽  
pp. 1-6 ◽  
Author(s):  
Chin Wei Lai
Keyword(s):  
Low Temperature ◽  
Composite Film ◽  
Adsorption Capacity ◽  
Surface Area ◽  
Anodic Oxidation ◽  
Active Surface ◽  
Optimum Concentration ◽  
Electrochemical Anodization ◽  
Active Surface Area ◽  
One Dimensional

A novel one-dimensional anodic CaO-TiO2nanotubes composite film was prepared using a rapid-anodic oxidation electrochemical anodization technique for low temperature CO2absorption application. This study aims to determine the optimum concentration of Ca(NO3)2·4H2O used as the CaO precursor for loading CaO species on TiO2nanotubes. In this study, an optimum content of CaO on TiO2nanotubes (0.15 at% of Ca element) could enhance the CO2adsorption capacity up to 2.45 mmol/g at 400°C. This behavior was attributed to the large active surface area of CaO species were covered on the surface of TiO2nanotubes. The conversion of CaO into CaCO3could be achieved effectively for CO2absorption during the carbonate looping process.

Improved Photocatalytic Oxidation of Organic Dye Using One-Dimensional Titania Nanotubes

2015 ◽  
Vol 1087 ◽  
pp. 186-190
Author(s):  
Chin Wei Lai ◽  
Emy Marlina Samsudin ◽  
Joon Ching Juan
Keyword(s):  
Photocatalytic Activity ◽  
Hydroxyl Radicals ◽  
Photocatalytic Oxidation ◽  
Active Surface ◽  
Organic Dye ◽  
Active Surface Area ◽  
Oxidation Reactions ◽  
Facile Hydrothermal Method ◽  
One Dimensional ◽  
Nanotubular Structure

Titania (TiO2) nanotubes were successfully synthesized via a facile hydrothermal method. The influence of starting material (TiO2 nanoparticles) content on the conversion of tubular structure during hydrothermal treatment was investigated. Based on the result obtained, it was found minimum 1 g of TiO2 nanoparticles was required for completing the transformation of nanotubular structure. The photocatalytic activity of TiO2 nanotubes was evaluated by degradation of organic methyl orange (MO) dye. Interestingly, one-dimensional TiO2 nanotubes exhibited high photocatalytic oxidation rate (78% degradation) under UV irradiation for 5 hours. The reason was attributed to the high active surface area to generate more hydroxyl radicals (∙OH) for triggering photocatalytic oxidation reactions on the inner and outer surface of TiO2 nanotubular structure.

Tenacious Mass Transfer Limitations Drive Catalytic Selectivity during Electrochemical Carbon Dioxide Reduction

2019 ◽  
Author(s):  
Kailun Yang ◽  
Recep Kas ◽  
Wilson A. Smith
Keyword(s):  
Surface Area ◽  
High Surface ◽  
High Surface Area ◽  
Catalyst Layer ◽  
Active Surface ◽  
Active Surface Area ◽  
High Concentration ◽  
Copper Electrodes ◽  
Surface Enhanced ◽  
Local Current

<p>This study evaluated the performance of the commonly used strong buffer electrolytes, i.e. phosphate buffers, during CO<sub>2</sub> electroreduction in neutral pH conditions by using in-situ surface enhanced infrared absorption spectroscopy (SEIRAS). Unfortunately, the buffers break down a lot faster than anticipated which has serious implications on many studies in the literature such as selectivity and kinetic analysis of the electrocatalysts. Increasing electrolyte concentration, surprisingly, did not extend the potential window of the phosphate buffers due to dramatic increase in hydrogen evolution reaction. Even high concentration phosphate buffers (1 M) break down within the potentials (-1 V vs RHE) where hydrocarbons are formed on copper electrodes. We have extended the discussion to high surface area electrodes by evaluating electrodes composed of copper nanowires. We would like highlight that it is not possible to cope with high local current densities on these high surface area electrodes by using high buffer capacity solutions and the CO<sub>2</sub> electrocatalysts are needed to be evaluated by casting thin nanoparticle films onto inert substrates as commonly employed in fuel cell reactions and up to now scarcely employed in CO<sub>2</sub> electroreduction. In addition, we underscore that normalization of the electrocatalytic activity to the electrochemical active surface area is not the ultimate solution due to concentration gradient along the catalyst layer.This will “underestimate” the activity of high surface electrocatalyst and the degree of underestimation will depend on the thickness, porosity and morphology of the catalyst layer. </p> <p> </p>

scholarly journals High-Performance Lead-Acid Batteries Enabled by Pb and PbO2 Nanostructured Electrodes: Effect of Operating Temperature

2021 ◽  
Vol 11 (14) ◽  
pp. 6357
Author(s):  
Roberto Luigi Oliveri ◽  
Maria Grazia Insinga ◽  
Simone Pisana ◽  
Bernardo Patella ◽  
Giuseppe Aiello ◽  
...  
Keyword(s):  
High Performance ◽  
Active Material ◽  
Active Surface ◽  
Effect Of Temperature ◽  
Active Surface Area ◽  
Polycarbonate Membrane ◽  
Nanostructured Electrodes ◽  
Lead Acid Batteries ◽  
Improved Stability ◽  
Lead Acid

Lead-acid batteries are now widely used for energy storage, as result of an established and reliable technology. In the last decade, several studies have been carried out to improve the performance of this type of batteries, with the main objective to replace the conventional plates with innovative electrodes with improved stability, increased capacity and a larger active surface. Such studies ultimately aim to improve the kinetics of electrochemical conversion reactions at the electrode-solution interface and to guarantee a good electrical continuity during the repeated charge/discharge cycles. To achieve these objectives, our contribution focuses on the employment of nanostructured electrodes. In particular, we have obtained nanostructured electrodes in Pb and PbO2 through electrosynthesis in a template consisting of a nanoporous polycarbonate membrane. These electrodes are characterized by a wider active surface area, which allows for a better use of the active material, and for a consequent increased specific energy compared to traditional batteries. In this research, the performance of lead-acid batteries with nanostructured electrodes was studied at 10 C at temperatures of 25, −20 and 40 °C in order to evaluate the efficiency and the effect of temperature on electrode morphology. The batteries were assembled using both nanostructured electrodes and an AGM-type separator used in commercial batteries.

THE ROLE OF MYELOPEROXIDASE AND NEUTROPHIL EXTRACELLULAR TRAPS IN THE PATHOGENESIS OF INFLAMMATORY BOWEL DISEASE

2021 ◽  
Vol 27 (Supplement_1) ◽  
pp. S4-S4
Author(s):  
Belal Chami ◽  
Gulfam Ahmad ◽  
Angie Schroder ◽  
Patrick San Gabriel ◽  
Paul Witting
Keyword(s):  
Disease Severity ◽  
Hypochlorous Acid ◽  
Tissue Injury ◽  
Activity Index ◽  
Critical Role ◽  
Neutrophil Migration ◽  
Sodium Sulphate ◽  
Host Tissue ◽  
Neutrophil Extracellular Trap

Abstract Neutrophils are short-lived immune cells that represent the major cell type recruited to the inflamed bowel releasing their azurophilic granules containing enzymes myeloperoxidase (MPO). Fecal and serum MPO levels has previously been shown to correlate to disease severity in IBD patients. MPO, in the presence of H2O2 and free Cl- undergoes a halogenation cycle, yielding the two-electron oxidant, hypochlorous acid (HOCl) - a potent bactericidal agent. However, chronic intestinal exposure to MPO/HOCl due to perpetual inflammation may cause secondary host-tissue injury and cell death. Neutrophil Extracellular Trap (NET)osis is a specialised form of neutrophil death where MPO is entrapped in a DNA scaffold and continues to elicit HOCl activity and may further contribute to host-tissue injury. We investigated the presence of NETs in surgically excised ileum samples from CD and healthy patients using advanced confocal microscopic techniques and found MPO, Neutrophil Elastase (NE) and Citrullinated Histone h3 (CitH3) - critical components of NET formation, individually positively correlate to the severity of histopathological intestinal injury. Furthermore, multiplex Opal™ IHC performed using LMS880 Airyscan-moduled microscopy with z-stacking revealed colocalization of NE, MPO, CitH3 and DAPI indicating the extensive presence of NETs in severely affected CD tissue. Using two pharmacological inhibitors of MPO in a dextran sodium sulphate (DSS) model of murine colitis, we demonstrated the pathological role of MPO in experimental colitis. MPO inhibitors, TEMPOL and AZD3241 delivered via daily i.p significantly rescued the course of colitis by abrogating clinical indices including body weight loss, disease activity index, inhibiting serum peroxidation, and preserving colon length, while significantly mitigating histoarchitectural damage associated with DSS-induced colitis. We also showed that MPO inhibition decreased neutrophil migration to the gut, suggesting MPO may play a role in perpetuating the inflammatory cell by further recruiting cells to the inflamed gut. Collectively, we have shown for the first time that MPO is not only an important clinical marker of disease severity but may also play a critical role in perpetuating host-tissue damage and inflammation.

Hollow structure engineering of FeCo alloy nanoparticles electrospun in nitrogen-doped carbon enables high performance flexible all-solid-state zinc–air batteries

2020 ◽  
Vol 4 (4) ◽  
pp. 1747-1753 ◽  
Author(s):  
Yuanyuan Ma ◽  
Wenjie Zang ◽  
Afriyanti Sumboja ◽  
Lu Mao ◽  
Ximeng Liu ◽  
...  
Keyword(s):  
Active Sites ◽  
High Performance ◽  
Hollow Structure ◽  
Active Surface ◽  
Oxygen Electrode ◽  
Active Surface Area ◽  
Active Components ◽  
Nitrogen Doped Carbon ◽  
Structure Engineering ◽  
Kinetics Of

Hollow structuring of active components is an effective strategy to improve the kinetics of oxygen electrode catalysts, arising from the increased the active surface area, the defects on the exposed surface, and the accessible active sites.

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