scholarly journals Carbon Nanotubes based Nanocomposites as Photocatalysts in Water Treatment

2021 ◽  
pp. 77-112
Author(s):  
T.L. Tan
Keyword(s):  
Carbon Nanotubes ◽  
Water Treatment ◽  
Photocatalytic Degradation ◽  
Water Demand ◽  
Metal Ion ◽  
Important Research ◽  
Important Research Topic ◽  
Persistent Organic Compounds ◽  
Tunable Morphology ◽  
Degradation Of Pollutants

The shortage of worldwide clean water and the increasing water demand are now ubiquitous problems around the world. Thus, efficient water treatment is an important research topic, of which phocatalysis is known as simplest and efficient technique utilized in the photocatalytic degradation of all major water pollutants, including heavy metal ion, organic and inorganic pollutants. In this context, the use of one- dimensional carbon nanotubes-based nanocomposites in water treatment have been widely demonstrated to be capable of removing persistent organic compounds due to their unique physical and electronic properties, large surface area, tunable morphology, biocompatible and chemical-environmental-thermal stability. This chapter begins with the discussion of the importance and properties of carbon nanotubes, and then briefs about the types and methods of preparation of carbon nanotubes-based nanocomposites in detail. The next section emphasizes the fundamentals of photocatalysis phenomenon and its proposed mechanism for the photocatalytic degradation of pollutants. The last section highlights the recent development in the carbon-based nanocomposites as photocatalyst in water treatment systems, supported by comprehensive literature account. Finally, the remaining challenges and perspectives for using carbon nanotubes-based nanocomposites are discussed.

scholarly journals Recent Achievements in Development of TiO2-Based Composite Photocatalytic Materials for Solar Driven Water Purification and Water Splitting

Materials ◽  
2020 ◽  
Vol 13 (6) ◽  
pp. 1338 ◽  
Author(s):  
Klara Perović ◽  
Francis M. dela Rosa ◽  
Marin Kovačić ◽  
Hrvoje Kušić ◽  
Urška Lavrenčič Štangar ◽  
...  
Keyword(s):  
Water Treatment ◽  
Transition Metal ◽  
Photocatalytic Degradation ◽  
Water Splitting ◽  
Water Purification ◽  
Degradation Mechanism ◽  
Living Environment ◽  
Solar Irradiation ◽  
Metal Chalcogenides ◽  
Photocatalytic Water Splitting

Clean water and the increased use of renewable energy are considered to be two of the main goals in the effort to achieve a sustainable living environment. The fulfillment of these goals may include the use of solar-driven photocatalytic processes that are found to be quite effective in water purification, as well as hydrogen generation. H2 production by water splitting and photocatalytic degradation of organic pollutants in water both rely on the formation of electron/hole (e−/h+) pairs at a semiconducting material upon its excitation by light with sufficient photon energy. Most of the photocatalytic studies involve the use of TiO2 and well-suited model compounds, either as sacrificial agents or pollutants. However, the wider application of this technology requires the harvesting of a broader spectrum of solar irradiation and the suppression of the recombination of photogenerated charge carriers. These limitations can be overcome by the use of different strategies, among which the focus is put on the creation of heterojunctions with another narrow bandgap semiconductor, which can provide high response in the visible light region. In this review paper, we report the most recent advances in the application of TiO2 based heterojunction (semiconductor-semiconductor) composites for photocatalytic water treatment and water splitting. This review article is subdivided into two major parts, namely Photocatalytic water treatment and Photocatalytic water splitting, to give a thorough examination of all achieved progress. The first part provides an overview on photocatalytic degradation mechanism principles, followed by the most recent applications for photocatalytic degradation and mineralization of contaminants of emerging concern (CEC), such as pharmaceuticals and pesticides with a critical insight into removal mechanism, while the second part focuses on fabrication of TiO2-based heterojunctions with carbon-based materials, transition metal oxides, transition metal chalcogenides, and multiple composites that were made of three or more semiconductor materials for photocatalytic water splitting.

scholarly journals An All-Batch Loss for Constructing Prediction Intervals

2021 ◽  
Vol 11 (4) ◽  
pp. 1728
Author(s):  
Hua Zhong ◽  
Li Xu
Keyword(s):  
Gradient Descent ◽  
State Of The Art ◽  
Prediction Interval ◽  
Feedforward Neural Networks ◽  
Important Research ◽  
Likelihood Principle ◽  
High Quality ◽  
Construction Methods ◽  
Important Research Topic ◽  
Benchmark Datasets

The prediction interval (PI) is an important research topic in reliability analyses and decision support systems. Data size and computation costs are two of the issues which may hamper the construction of PIs. This paper proposes an all-batch (AB) loss function for constructing high quality PIs. Taking the full advantage of the likelihood principle, the proposed loss makes it possible to train PI generation models using the gradient descent (GD) method for both small and large batches of samples. With the structure of dual feedforward neural networks (FNNs), a high-quality PI generation framework is introduced, which can be adapted to a variety of problems including regression analysis. Numerical experiments were conducted on the benchmark datasets; the results show that higher-quality PIs were achieved using the proposed scheme. Its reliability and stability were also verified in comparison with various state-of-the-art PI construction methods.

A Bibliometric Review on Outcome-Based Learning for Graduate Employability: Mapping the Research Front

2021 ◽  
pp. 002205742110164
Author(s):  
Mohammad Zahir Raihan ◽  
Md. Abul Kalam Azad
Keyword(s):  
Research Trend ◽  
Future Research ◽  
Research Front ◽  
Important Research ◽  
R Software ◽  
Future Research Agenda ◽  
Graduate Employability ◽  
Important Research Topic ◽  
Bibliometric Review ◽  
First Time

The outcome-based learning for graduate employability in higher education has been an important research topic among the policymakers, academicians, and researchers over the years. Yet, no bibliometric review on this topic has been published. This study, for the first time, examines bibliometric analysis on this topic examining current research trend and future research agenda. The bibliometrix package in R software and VOSviewer software are used for visualization and interpretation of results. A content analysis is performed to manually examine the bibliometric results.

Rapid photocatalytic degradation of cationic organic dyes using Li-doped Ni/NiO nanocomposites and their electrochemical performance

2021 ◽  
Author(s):  
R. Ranjitha ◽  
K. N. Meghana ◽  
V. G. Dileep Kumar ◽  
Aarti S. Bhatt ◽  
B. K. Jayanna ◽  
...  
Keyword(s):  
Energy Storage ◽  
Water Treatment ◽  
Electrochemical Performance ◽  
Photocatalytic Degradation ◽  
Organic Dyes

This work reports novel bi-functional Li-doped Ni/NiO nanocomposites as potential candidates for energy storage and water treatment applications.

Modulation of Electronic Properties of Single Wall Carbon Nanotubes by the Presence of an Ionic Shell

2006 ◽  
Vol 915 ◽  
Author(s):  
Vladimir Dobrokhotov ◽  
Chris Berven
Keyword(s):  
Carbon Nanotubes ◽  
Heavy Metal ◽  
Band Structure ◽  
Metal Ion ◽  
Single Wall Carbon Nanotubes ◽  
Functionalized Carbon Nanotubes ◽  
Ion Sensing ◽  
Fixed Distance ◽  
Metal Ion Sensing ◽  
Heavy Metal Ion Sensing

AbstractWe report the change to the band structure of two types of carbon nanotubes due to the presence of an isolated, non-conducting, uniformly charged shell held at a fixed distance above their surfaces. We find that, depending on the chirality of the nanotube, the strain on the lattice causes the dispersion relationships to change. This change can result in a modification of the band structure which can induce a metal-semiconductor transition. We consider these effects as a possible mechanism for heavy-metal ion sensing by functionalized carbon-nanotubes.

Conformal Optimization Algorithm for Undevelopable Surfaces and its Application

2014 ◽  
Vol 602-605 ◽  
pp. 3570-3574
Author(s):  
Zhen Hua Luo ◽  
Fen Jiang
Keyword(s):  
Approximation Algorithms ◽  
Optimization Algorithm ◽  
Manufacturing Process ◽  
Research Topic ◽  
Important Research ◽  
Computer Aided Geometric Design ◽  
Industrial Manufacturing ◽  
Important Research Topic ◽  
Computer Aided ◽  
Planar Materials

In the industrial manufacturing process, most kinds of surfaces are processed by planar materials, but undevelopable surfaces are difficult develop to the plane. The approximation algorithms to develop a undevelopable surface is an important research topic in Computer Aided Geometric Design (CAGD). In this paper, we propose a new approximation algorithms based optimization algorithm. We guarantee the deformation vector make the minimum changes during the developing process. In the paper, some numerical example are given and the can illustrate the our method is effective.

scholarly journals Field Emission from Carbon Films Deposited by Controlled-Low-Energy Beams and CVD Sources

1999 ◽  
Vol 585 ◽  
Author(s):  
Douglas H. Lowndes ◽  
Vladimir I. Merkulov ◽  
L. R. Baylor ◽  
G. E. Jellison ◽  
D. B. Poker ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Surface Morphology ◽  
Field Emission ◽  
Metal Ion ◽  
Ion Beam ◽  
Pyrolytic Graphite ◽  
Carbon Film ◽  
Chemical Vapor ◽  
Carbon Films ◽  
Damage Site

AbstractThe principal interests in this work are energetic-beam control of carbon-film properties and the roles of doping and surface morphology in field emission. Carbon films with variable sp3-bonding fraction were deposited on n-type Si substrates by ArF (193 nm) pulsed-laser ablation (PLA) of a pyrolytic graphite target, and by direct metal ion beam deposition (DMIBD) using a primary Cs+ beam to generate the secondary C- deposition beam. The PLA films are undoped while the DMIBD films are doped with Cs. The kinetic energy (KE) of the incident C atoms/ions was controlled and varied over the range from ∼25 eV to ∼175 eV. Earlier studies have shown that C films' sp3-bonding fraction and diamond-like properties can be maximized by using KE values near 90 eV. The films' surface morphology, sp3–bonding fraction, and Cs-content were determined as a function of KE using atomic force microscopy, TEM/EELS, Rutherford backscattering and nuclear reaction measurements, respectively. Field emission (FE) from these very smooth undoped and Cs-containing films is compared with the FE from two types of deliberately nanostructured carbon films, namely hot-filament chemical vapor deposition (HF-CVD) carbon and carbon nanotubes grown by plasma-enhanced CVD. Electron field emission (FE) characteristics were measured using ∼25-μm, ∼5-μm and ∼1-μm diameter probes that were scanned with ∼75 nm resolution in the x-, y-, and z-directions in a vacuum chamber (∼5 × 10-7 torr base pressure) equipped with a video camera for viewing. The hydrogen-free and very smooth a-D or a-C films (with high or low sp3 content, and with or without ∼1% Cs doping) produced by PLD and DMIBD are not good field emitters. Conditioning accompanied by arcing was required to obtain emission, so that their subsequent FE is characteristic of the arc-produced damage site. However, deliberate surface texturing can eliminate the need for conditioning, apparently by geometrical enhancement of the local electric field. But the most promising approach for producing macroscopically flat FE cathodes is to use materials that are highly nanostructured, either by the deposition process (e.g. HF-CVD carbon) or intrinsically (e.g. carbon nanotubes). HF-CVD films were found to combine a number of desirable properties for FE displays and vacuum microelectronics, including the absence of conditioning, low turn-on fields, high emission site density, and apparent stability and durability during limited long-term testing. Preliminary FE measurements revealed that vertically aligned carbon nanotubes are equally promising.

Global coronal and heliospheric magnetic field modelling for Solar Orbiter

2021 ◽  
Author(s):  
Thomas Wiegelmann ◽  
Thomas Neukirch ◽  
Iulia Chifu ◽  
Bernd Inhester
Keyword(s):  
Magnetic Field ◽  
Solar Rotation ◽  
Coronal Magnetic Field ◽  
Important Research ◽  
Parker Spiral ◽  
Important Research Topic ◽  
Mhd Equilibria ◽  
Solar Wind Flow ◽  
Nonlinear Force

<p>Computing the solar coronal magnetic field and plasma<br>environment is an important research topic on it's own right<br>and also important for space missions like Solar Orbiter to<br>guide the analysis of remote sensing and in-situ instruments.<br>In the inner solar corona plasma forces can be neglected and<br>the field is modelled under the assumption of a vanishing<br>Lorentz-force. Further outwards (above about two solar radii)<br>plasma forces and the solar wind flow has to be considered.<br>Finally in the heliosphere one has to consider that the Sun<br>is rotating and the well known Parker-spiral forms.<br>We have developed codes based on optimization principles<br>to solve nonlinear force-free, magneto-hydro-static and<br>stationary MHD-equilibria. In the present work we want to<br>extend these methods by taking the solar rotation into account.</p>

Sign in / Sign up

Export Citation Format

Share Document