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Syed N Ahmed, Waseem Haider
There has been a considerable amount of research in the development of sustainable water treatment techniques capable of improving the quality of water. Unavailability of drinkable water is a crucial issue especially in regions where conventional drinking water treatment systems fail to eradicate aquatic pathogens, toxic metal ions and industrial waste. The research and development in this area have given rise to a new class of processes called Advanced Oxidation Processes, particularly in the form of heterogeneous photocatalysis, which converts photon energy into chemical energy...
May 22, 2018: Nanotechnology
Wen-Long Wang, Qian-Yuan Wu, Nan Huang, Zi-Bin Xu, Min-Yong Lee, Hong-Ying Hu
UV based advanced oxidation processes (UV-AOPs) that efficiently eliminate organic pollutants during water treatment have been the subject of numerous investigations. Most organic pollutants are not completely mineralized during UV-AOPs but are partially oxidized into transformation products (TPs), thereby adding complexity to the treated water and posing risks to humans, ecological systems, and the environment. While the degradation kinetics and mechanisms of pollutants have been widely documented, there is little information about the risks associated with TPs...
May 15, 2018: Water Research
Duo Zhang, Han Wang, Carsten Bolm
Reacting N-Br sulfoximines with ammonium thiocyanate leads to unprecedented sulfur reagents, which add to vinyl arenes under photocatalysis via N-centered sulfoximidoyl radicals. As a result, 1,2-difunctionalised products are obtained, which can subsequently be derivatised taking advantage of the unique properties of the thiocyanate group.
May 21, 2018: Chemical Communications: Chem Comm
Aleksandr Savateev, Bogdan Kurpil, Artem Mishchenko, Guigang Zhang, Markus Antonietti
Potassium poly(heptazine imide), a carbon nitride based semiconductor with high structural order and a valence band potential of +2.2 V vs. NHE, in the presence of hole scavengers and under visible light irradiation gives the corresponding polymeric radical anion, in which the specific density of unpaired electrons reaches 112 μmol g-1 . The obtained polymeric radical anion is stable under anaerobic conditions for several hours. It was characterized using UV-vis absorption, time resolved and steady state photoluminescence spectra...
April 14, 2018: Chemical Science
Gang Xiao, Peifeng Li, Yilin Zhao, Shengnan Xu, Haijia Su
Green and efficient procedures are highly required for the chemoselective hydrogenation of functionalized nitroarenes to industrially important anilines. Here, we show that visible-light-driven, chemoselective hydrogenation of functionalized nitroarenes bearing the sensitive groups to anilines can be achieved in good to excellent yields (82-100%) in water under relatively mild conditions, catalyzed by low-cost and recyclable graphitic carbon nitride. It is also applicable in gram-scale reaction with 86% yield of aniline...
May 20, 2018: Chemistry, An Asian Journal
M Trejo-Valdez, S R Hernández-Guzmán, M E Manriquez-Ramírez, H Sobral, H Martínez-Gutiérrez, C Torres-Torres
Removal of hexavalent chromium was accomplished by using photocatalyst materials of TiO2 doped with tungsten oxide, environmental air as oxygen supply and white light as irradiation source. Dichromate anions in concentration ranges of 50 to 1000 μg/L were removed by means of aqueous dispersions of TiO2 doped with tungsten. The aqueous chromium analyses were performed by Differential Pulse Voltammetry technique. Additionally, mineralization of CO2 gas was promoted by the photocatalysis process, as was clearly shown by Raman spectroscopy and X-ray Photoelectron Spectroscopy (XPS) analyses obtained from the TiO2 samples recovered after photocatalytic experiments...
May 15, 2018: Journal of Hazardous Materials
Guifang Ge, Xinwen Guo, Chunshan Song, Zhongkui Zhao
Developing a facile method to overcome the intrinsic shortcomings of g-C3N4 photocatalyst concerning its insufficient visible-light absorption and dissatisfactory separation efficiency of charge carriers is of great significance but remains a challenge. In this work, we report, for the first time, a sapiential strategy for preparing highly-efficient nitrogen deficient g-C3N4 featuring bunchy microtubes (R-TCN) via a KOH-assisted hydrothermal treatment of rodlike melamine-cyanuric acid supramolecular aggregates (RMCA) followed by heating the reconstructed RMCA, in which KOH serves as an all-rounder for breaking hydrogen bonds, accelerating hydrolysis of melamine and nitrogen defects forming...
May 18, 2018: ACS Applied Materials & Interfaces
Wen-Jing Xiao, Quan-Quan Zhou, You-Quan Zou, Liang-Qiu Lu
Visible-light photocatalysis is a rapidly developing and powerful strategy to initiate organic transformations as it closely adheres to the tenants of green and sustainable chemistry. Generally, most visible-light-induced photochemical reactions occur through single-electron transfer (SET) pathways. Recently, visible-light-induced energy transfer (EnT) reactions have received considerable attentions from the synthetic community as this strategy provides a distinct reaction pathway, and remarkable achievements have been made in this field...
May 18, 2018: Angewandte Chemie
Dan Preston, Keith C Gordon, Joshua J Sutton, James D Crowley
We report a simple, low symmetry 2-(1-(pyridine-4-methyl)-1H-1,2,3-triazol-4-yl)pyridine ligand which has both monodentate and bidentate binding sites. With platinumII and/or palladiumII ions, two examples of a new nona-nuclear metallo-assembly have been accessed. These complexes have been characterized by nuclear magnetic resonance (NMR) spectroscopies, electrospray mass spectrometry (ESI-MS), and in key cases, X-ray crystallography. The cages possess three clefts comprised of planar cationic panels. This structural feature enables the binding of planar aromatic guests such as anthracene...
May 18, 2018: Angewandte Chemie
Ken-Lin Chang, Xiao-Qin Wang, Ye-Ju Han, Hao Deng, Jing-Yong Liu, Yuan-Chung Lin
This work evaluated the effectiveness of rice straw pretreatment using a TiO₂/UV system in the presence of oxidants. The effects of TiO₂ concentrations, pH and photocatalysis time were investigated. Inorganic oxidants including H₂O2, K₂S₂O₈, and KIO₄ were added to further enhance the effect on enzymatic hydrolysis of rice straw. The TiO₂/UV/ H₂O₂ pretreatment showed a higher amount of released reducing sugar (8.88 ± 0.10 mg/mL, compared to 5.47 ± 0.03 mg/mL in untreated sample). Composition analyses of rice straw after the TiO₂/UV/H₂O₂ pretreatment showed partial lignin and hemicellulose removal...
May 16, 2018: Materials
Jing Fang, Jiajun Gu, Qinglei Liu, Wang Zhang, Huilan Su, Di Zhang
Localized surface plasmon resonance (LSPR) of plasmonic metals (e.g. Au) can help semiconductors improve their photocatalytic hydrogen (H2) production performance. However, artificial synthesis of hierarchical plasmonic structures down to nanoscales is usually difficult. Here, we adopt butterfly wing scales from Morpho didius to fabricate three dimensional (3D) CdS/Au butterfly wing scales for plasmonic photocatalysis. The as-prepared materials well inherit the pristine hierarchical bio-structures. The 3D CdS/Au butterfly wing scales exhibit high H2 production rate (221...
May 17, 2018: ACS Applied Materials & Interfaces
Gang Wang, Junpeng Wang, Ping Yang
BiOI nanoplatelets were successfully grown on carbon fibers (CFs) surface, which had been activated in acid and alkaline solution (CFs-AC and CFs-AL). The BiOI microspheres composed of nanoplatelets were distributed relatively equally on CFs surface after acidizing while the CFs treatment by alkaline solution the BiOI nanoplatelets cannot combined tightly with CFs. The as-prepared BiOI/CFs was characterized by X-ray diffraction, scanning electron microscopy and UV-vis diffuse reflectance spectroscopy. The possible mechanism of BiOI/CFs formation was attributed to the electrostatic adsorption in reaction process...
January 1, 2018: Journal of Nanoscience and Nanotechnology
Urvashi Sharma, P Jeevanandam
TixMg1-xO solid solutions with tunable band gap are potential candidates for various applications such as photocatalysis, water splitting, dielectrics, etc. Present study reports the synthesis of TixMg1-xO (x = 0.02 to 0.5) solid solution nanoparticles via a simple sol-gel method. First, layered double hydroxides (precursors) are produced by sol-gel method, which on calcination produce the TixMg1-xO solid solutions. The effect of concentration of titanium (introduced as titanium isopropoxide during the synthesis) on the optical properties of TixMg1-xO solid solution nanoparticles has been investigated...
January 1, 2018: Journal of Nanoscience and Nanotechnology
Yanan Wang, Hongli Guo, Qijing Zheng, Wissam A Saidi, Jin Zhao
Solvated electron states at oxide/aqueous interface represent the lowest energy charge transfer pathways, thereby playing an important role in photocatalysis and electronic device applications. However, their energies are usually higher than the conduction band minimum (CBM), which makes the solvated electrons difficult to utilize in charge transfer processes. Thus, it is essential to stabilize the energy of the solvated electron states. In this report, taking LaAlO3/SrTiO3 (LAO/STO) oxide heterostructure with H2O adsorbed monolayer as a prototypical system, we show using DFT and ab initio time dependent nonadiabatic molecular dynamics simulation that the energy and dynamics of solvated electrons can be tuned by the electric field in the polar-nonpolar oxide heterostructure...
May 16, 2018: Journal of Physical Chemistry Letters
Fabio Lima, Lars Grunenberg, Husaini B A Rahman, Ricardo Labes, Joerg Sedelmeier, Steven V Ley
We report an acridium-based organic photocatalyst as an efficient replacement for iridium-based photocatalysts to oxidise boronic acid derivatives by a single electron process. Furthermore, we applied the developed catalytic system to the synthesis of four active pharmaceutical ingredients (APIs). A straightforward scale up approach using continuous flow photoreactors is also reported affording gram an hour throughput.
May 16, 2018: Chemical Communications: Chem Comm
Dandan Li, Shu-Hong Yu, Hai-Long Jiang
The exploitation of photocatalysts that harvest solar spectrum as broad as possible remains a high-priority target yet grand challenge. In this work, for the first time, metal-organic framework (MOF) composites are rationally fabricated to achieve broadband spectral response from UV to near-infrared (NIR) region. In the core-shell structured upconversion nanoparticles (UCNPs)-Pt@MOF/Au composites, the MOF is responsive to UV and a bit visible light, the plasmonic Au nanoparticles (NPs) accept visible light, whereas the UCNPs absorb NIR light to emit UV and visible light that are harvested by the MOF and Au once again...
May 15, 2018: Advanced Materials
Mohammad Ehtisham Khan, Mohammad Mansoob Khan, Moo Hwan Cho
Metal-graphene nanostructures (NSs) as photocatalysts, prepared using simple and scalable synthesis methods, are gaining heightened attention as novel materials for water treatment and environmental remediation applications. Graphene, the unique few layers sheet-like arrangement of sp2 hybridized carbon atoms, has an inimitable two-dimensional (2D) structure. The material is highly conductive, has high electron mobility and an extremely high surface area, and can be produced on a large scale at low cost. Accordingly, it has been considered as an essential base component for producing various metal-based NSs...
May 15, 2018: Nanoscale
Bo You, Guanqun Han, Yujie Sun
Renewable energy-driven hydrogen production from electrocatalytic and photocatalytic water splitting has been widely recognized as a promising approach to utilize green energy resources and hence reduces our dependence on legacy fossil fuels as well as alleviates net carbon dioxide emissions. The realization of large-scale water splitting, however, is mainly impeded by its slow kinetics, particularly because of its sluggish anodic half reaction, the oxygen evolution reaction (OER), whose product O2 is ironically not of high value...
May 15, 2018: Chemical Communications: Chem Comm
Joana Ângelo, Pedro Magalhães, Luísa Andrade, Luís M Madeira, Adélio Mendes
Photocatalysis was recognised as a suitable process for the photoabatement of atmospheric pollutants. The photooxidation mechanism on TiO2 has been widely studied. However, recent studies demonstrated that the very often-assumed photooxidation intermediated by the hydroxyl radical cannot explain all the experimental observations. Indeed, this study contributes for a new understanding of NO photooxidation. First, the adsorption equilibrium isotherms of NO, NO2 and H2 O on the photocatalyst, Aeroxide® P25 from Evonik Industries, were obtained...
May 11, 2018: Environmental Pollution
Walter Den, Virender K Sharma, Mengshan Lee, Govind Nadadur, Rajender S Varma
Anthropogenic climate change, principally induced by the large volume of carbon dioxide emission from the global economy driven by fossil fuels, has been observed and scientifically proven as a major threat to civilization. Meanwhile, fossil fuel depletion has been identified as a future challenge. Lignocellulosic biomass in the form of organic residues appears to be the most promising option as renewable feedstock for the generation of energy and platform chemicals. As of today, relatively little bioenergy comes from lignocellulosic biomass as compared to feedstock such as starch and sugarcane, primarily due to high cost of production involving pretreatment steps required to fragment biomass components via disruption of the natural recalcitrant structure of these rigid polymers; low efficiency of enzymatic hydrolysis of refractory feedstock presents a major challenge...
2018: Frontiers in Chemistry
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