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https://www.readbyqxmd.com/read/28643362/-super-reducing-photocatalysis-consecutive-energy-and-electron-transfers-with-polycyclic-aromatic-hydrocarbons
#1
Malte Brasholz
Donation welcome: Recent developments in visible-light photocatalysis allow the utilization of increasingly negative reduction potentials. Successive energy and electron transfer with polycyclic aromatic hydrocarbons enables the catalytic formation of strongly reducing arene radical anions, classical stoichiometric reagents for one-electron reduction in organic synthesis.
June 23, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/28640637/designing-transmitter-ligands-that-mediate-energy-transfer-between-semiconductor-nanocrystals-and-molecules
#2
Zhiyuan Huang, Ming Lee Tang
Molecular control of energy transfer is an attractive proposition because it allows chemists to synthetically tweak various kinetic and thermodynamic factors. In this Perspective, we examine energy transfer between semiconductor nano-crystals (NCs) and π-conjugated molecules, focusing on the transmitter ligand at the organic-inorganic interface. Efficient transfer of triplet excitons across this interface allows photons to be directed for effective use of the entire solar spectrum. For example, a photon upconversion system composed of semiconductor NCs as sensitizers, bound organic ligands as transmitters, and molecular annihilators has the advantage of large, tunable absorption cross-sections across the visible and near infrared wavelengths...
June 22, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28640479/visible-light-photocatalysis-of-6%C3%AF-heterocyclization
#3
Martin Derwyn Smith, Niels Münster, Nicholas Parker, Lucy van Dijk, Robert Paton
Photo-mediated 6π cyclization is a valuable method for the formation of fused heterocyclic systems. Here we demonstrate that irradiation of cyclic 2-aryloxyketones with blue LED light in the presence of an Ir(III) complex leads to efficient and high yielding arylation across a panoply of substrates by energy transfer. 2-arylthioketones and 2-arylaminoketones also cyclize effectively under these conditions. Quantum calculation demonstrates that the reaction proceeds via conrotatory ring closure in the triplet excited state...
June 22, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/28640388/electrostatic-driven-exfoliation-and-hybridization-of-2d-nanomaterials
#4
Guijian Guan, Jing Xia, Shuhua Liu, Yuan Cheng, Shiqiang Bai, Si Yin Tee, Yong-Wei Zhang, Ming-Yong Han
Here, direct and effective electrostatic-driven exfoliation of tungsten trioxide (WO3 ) powder into atomically thin WO3 nanosheets is demonstrated for the first time. Experimental evidence together with theoretical simulations clearly reveal that the strong binding of bovine serum albumin (BSA) on the surface of WO3 via the protonation of NH2 groups in acidic conditions leads to the effective exfoliation of WO3 nanosheets under sonication. The exfoliated WO3 nanosheets have a greatly improved dispersity and stability due to surface-protective function of BSA, and exhibit a better performance and unique advantages in applications such as visible-light-driven photocatalysis, high-capacity adsorption, and fast electrochromics...
June 22, 2017: Advanced Materials
https://www.readbyqxmd.com/read/28639787/recent-advances-in-radical-c-h-activation-radical-cross-coupling
#5
Hong Yi, Guoting Zhang, Huamin Wang, Zhiyuan Huang, Jue Wang, Atul K Singh, Aiwen Lei
Research and industrial interest in radical C-H activation/radical cross-coupling chemistry has continuously grown over the past few decades. These reactions offer fascinating and unconventional approaches toward connecting molecular fragments with high atom- and step-economy that are often complementary to traditional methods. Success in this area of research was made possible through the development of photocatalysis and first-row transition metal catalysis along with the use of peroxides as radical initiators...
June 22, 2017: Chemical Reviews
https://www.readbyqxmd.com/read/28639645/developing-a-ferroelectric-nanohybrid-for-enhanced-photocatalysis
#6
Zhipeng Wang, Jianmin Song, Feng Gao, Ran Su, Dawei Zhang, Yang Liu, Congcong Xu, Xiaojie Lou, Yaodong Yang
We develop a ferroelectric nanohybrid that improves photocatalytic efficiency by reducing the recombination of holes and electron charge carriers. In particular, the size of uniformly dispersed ferroelectric BaTiO3 in the nanohybrid reaches the critical size of a monodomain, which avoids the need for a poling process for switching the ferroelectric polarization.
June 22, 2017: Chemical Communications: Chem Comm
https://www.readbyqxmd.com/read/28638073/plasmon-induced-selective-carbon-dioxide-conversion-on-earth-abundant-aluminum-cuprous-oxide-antenna-reactor-nanoparticles
#7
Hossein Robatjazi, Hangqi Zhao, Dayne F Swearer, Nathaniel J Hogan, Linan Zhou, Alessandro Alabastri, Michael J McClain, Peter Nordlander, Naomi J Halas
The rational combination of plasmonic nanoantennas with active transition metal-based catalysts, known as 'antenna-reactor' nanostructures, holds promise to expand the scope of chemical reactions possible with plasmonic photocatalysis. Here, we report earth-abundant embedded aluminum in cuprous oxide antenna-reactor heterostructures that operate more effectively and selectively for the reverse water-gas shift reaction under milder illumination than in conventional thermal conditions. Through rigorous comparison of the spatial temperature profile, optical absorption, and integrated electric field enhancement of the catalyst, we have been able to distinguish between competing photothermal and hot-carrier driven mechanistic pathways...
June 21, 2017: Nature Communications
https://www.readbyqxmd.com/read/28636366/oxygenation-via-c-h-c-c-bond-activation-with-molecular-oxygen
#8
Yu-Feng Liang, Ning Jiao
The selective oxidation of organic molecules is a fundamentally important component of modern synthetic chemistry. In the past decades, direct oxidative C-H and C-C bond functionalization has proved to be one of the most efficient and straightforward methods to synthesize complex products from simple and readily available starting materials. Among these oxidative processes, the use of molecular oxygen as a green and sustainable oxidant has attracted considerable attention because of its highly atom-economical, abundant, and environmentally friendly characteristics...
June 21, 2017: Accounts of Chemical Research
https://www.readbyqxmd.com/read/28636086/selective-and-tunable-near-infrared-and-visible-light-transmittance-of-moo3-x-nanocomposites-with-different-crystallinity
#9
Ning Li, Yamei Li, Guangyao Sun, Yining Ma, Tianci Chang, Shidong Ji, Heliang Yao, Xun Cao, Shanhu Bao, Ping Jin
In this Communication, we report MoO3-x nanocomposites in which the near-infrared and visible light transmittance can be selectively modulated through the crystallinity. The MoO3-x nanocomposites were fabricated by a hydrothermal method, and their optical properties were characterized by UV-Vis spectrometer. The obtained results proved the possibility to tune the nanocomposite's optical properties in the UV/Visible spectral region: crystalline MoO3 mainly regulates the near-infrared range (800-2600 nm), and amorphous MoO3-x mainly changes the visible range from 350 nm to 800 nm and MoO3-x , with semi-crystalline structures mainly modulating around 800-1000 nm...
June 21, 2017: Chemistry, An Asian Journal
https://www.readbyqxmd.com/read/28635079/oxygen-vacancy-mediated-photocatalysis-of-biocl-reactivity-selectivity-and-perspective
#10
Hao Li, Jie Li, Zhihui Ai, Falong Jia, Lizhi Zhang
Semiconductor photocatalysis is a trustworthy approach to harvest clean solar light for energy conversions, while state-of-the-art catalytic efficiencies are unsatisfactory because of the finite light response and/or robust charge carriers' recombination. Along with the development of modern material characterization techniques and electronic-structure computations, oxygen vacancies (OVs) on real photocatalysts surface, even in infinitesimal concentration, are found to play a more decisive role in determining the kinetics, energetics and mechanisms of photocatalytic reactions...
June 20, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/28631780/tuning-the-photocatalytic-activity-of-bismuth-wolframate-towards-selective-oxidations-for-the-biorefinery-driven-by-solar-light
#11
Rosaria Ciriminna, Riccardo Delisi, Francesco Parrino, Leonardo Palmisano, Mario Pagliaro
The sol-gel entrapment of nanostructured Bi2WO6 enhances the activity and the selectivity of the short-gap semiconductor in the sunlight-driven photo-oxidation of trans-ferulic and trans-cinnamic acid dissolved in water with air as the primary oxidant. Valuable products such as vanillin, benzaldehyde, benzoic acid and vanillic acid are obtained. This provides the proof of concept that photocatalysis could be a promising technology in tomorrow's solar biorefineries.
June 20, 2017: Chemical Communications: Chem Comm
https://www.readbyqxmd.com/read/28628874/a-building-blocks-strategy-for-preparing-photocatalytically-active-anatase-tio2-rutile-sno2-heterostructures-by-hydrothermal-annealing
#12
Vagner Romito de Mendonça, Waldir Avansi, Raul Arenal, Caue Ribeiro
Effective heterostructures for photocatalysis need to present good electron-hole mobility among phases, a feature that is only attained with satisfactory interface quality. For very small sizes and with a stable colloidal state, the oriented attachment mechanism can be used to prepare suitable structures by means of a building blocks strategy, whereby preformed nanoparticles are used to control the desired amount of each phase in the heterostructure. Here, we show the success of this strategy for anatase TiO2/rutile SnO2 heterostructures, applying conventional hydrothermal annealing, where successive collisions among particles increase the probability of oriented attachment...
June 9, 2017: Journal of Colloid and Interface Science
https://www.readbyqxmd.com/read/28628868/an-overview-on-exploration-and-environmental-impact-of-unconventional-gas-sources-and-treatment-options-for-produced-water
#13
REVIEW
Tânia L S Silva, Sergio Morales-Torres, Sérgio Castro-Silva, José L Figueiredo, Adrián M T Silva
Rising global energy demands associated to unbalanced allocation of water resources highlight the importance of water management solutions for the gas industry. Advanced drilling, completion and stimulation techniques for gas extraction, allow more economical access to unconventional gas reserves. This stimulated a shale gas revolution, besides tight gas and coalbed methane, also causing escalating water handling challenges in order to avoid a major impact on the environment. Hydraulic fracturing allied to horizontal drilling is gaining higher relevance in the exploration of unconventional gas reserves, but a large amount of wastewater (known as "produced water") is generated...
June 16, 2017: Journal of Environmental Management
https://www.readbyqxmd.com/read/28628307/present-perspectives-of-advanced-characterization-techniques-in-tio2-based-photocatalysts
#14
Chengzhi Luo, Xiaohui Ren, Zhigao Dai, Yupeng Zhang, Xiang Qi, Chunxu Pan
TiO2 is the most investigated photocatalyst because of its non-toxicity, low cost, chemical stability, and strong photooxidative ability. Due to the morphology and structure dependent photocatalytic properties of TiO2, accurate characterization of the crystal and electronic structures of TiO2-based materials and their performance during the photocatalytic process is crucial not only for understanding the photocatalytic mechanism but also for providing experimental guidelines as well as a theoretical framework for the synthesis of high performance photocatalysts...
June 19, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/28627526/polymeric-carbon-nitride-for-solar-hydrogen-production
#15
Xiaobo Li, Anthony F Masters, Thomas Maschmeyer
If solar hydrogen production from water is to be a realistic candidate for industrial hydrogen production, the development of photocatalysts, which avoid the use of expensive and/or toxic elements is highly desirable from a scalability, cost and environmental perspective. Metal-free polymeric carbon nitride is an attractive material that can absorb visible light and produce hydrogen from water. This article reviews recent developments in polymeric carbon nitride as used in photocatalysis and then develops the discussion focusing on the three primary processes of a photocatalytic reaction: light-harvesting, carrier generation/separation/transportation and surface reactions...
June 19, 2017: Chemical Communications: Chem Comm
https://www.readbyqxmd.com/read/28622582/porous-mn-doped-g-c3n4-photocatalysts-for-enhanced-synergetic-degradation-under-visible-light-illumination
#16
Ji-Chao Wang, Cheng-Xing Cui, Ying Li, Lu Liu, Yu-Ping Zhang, Weina Shi
Photocatalytic degradation by semiconductors is an ideal way to solve the environmental problem. Here, the porous Mn doped g-C3N4 photocatalyst was synthesized by the calcination-refluxing method. The as-prepared g-C3N4 exhibits the high activity of photocatalytic degradation under visible light irradiation ( > 400nm) in the mixed system of Cr(VI) and organic pollutants. Especially, the photocatalytic activity of Cr(VI) reduction was increased from 9.5% to 76.5%, while that of Rhodamine B(RhB) degradation was enhanced from 15...
June 8, 2017: Journal of Hazardous Materials
https://www.readbyqxmd.com/read/28622467/h2o-adsorption-on-wo3-and-wo3-x-001-surfaces
#17
Elisa Albanese, Cristiana Di Valentin, Gianfranco Pacchioni
The nature of interaction of water with WO3 surface is of crucial importance for the use of this semiconductor oxide in photocatalysis. In this work, we investigate water adsorption and dissociation on both clean and O-deficient (001) WO3 surfaces by means of an accurate DFT approach. The O vacancy formation energy (computed with respect to O2) has been evaluated for all possible surface configurations and the removal of the terminal O atom along the c axis is found to be preferred, costing about half the corresponding energy in the bulk...
June 16, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/28618371/photodegradation-of-4-chlorophenoxyacetic-acid-under-visible-led-activated-n-doped-tio2-and-the-mechanism-of-stepwise-rate-increment-of-the-reused-catalyst
#18
Amal Abdelhaleem, Wei Chu
Photodegradation of 4-chlorophenoxyacetic acid (4-CPA) was systematically investigated using N-doped TiO2 (N-TiO2) under commercially available visible light emitting diode (Vis LED) as a novel Vis LED illumination in photocatalysis applications. The synergetic effect of Vis LED/N-TiO2 process was studied in detail by varying reaction conditions including the initial concentration of 4-CPA, catalyst dosage, light intensity, and initial pH. Additionally, the influence of inorganic anions and radical scavengers on the performance of the Vis LED/N-TiO2 process was also evaluated...
May 31, 2017: Journal of Hazardous Materials
https://www.readbyqxmd.com/read/28613830/photocatalysis-based-nanoprobes-using-noble-metal-semiconductor-heterostructure-for-visible-light-driven-in-vivo-detection-of-mercury
#19
Lihua Zhi, Xiaofan Zeng, Hao Wang, Jun Hai, Xiangliang Yang, Baodui Wang, Yanhong Zhu
The development of sensitive and reliable methods to monitor the presence of mercuric ions in cells and organisms is of great importance to biological research and biomedical applications. In this work, we propose a strategy to construct a solar-driven nanoprobe using a 3D Au@MoS2 heterostructure as a photocatalyst and rhodamine B (RhB) as a fluorescent and color change reporter molecule for monitoring Hg2+ in living cells and animals. The sensing mechanism is based on the photoinduced electron formation of gold amalgam in the 3D Au@MoS2 heterostructure under visible light illumination...
June 14, 2017: Analytical Chemistry
https://www.readbyqxmd.com/read/28613295/3d-porous-zno-sns-p-n-heterojunction-for-visible-light-driven-photocatalysis
#20
Lijing Wang, Hongju Zhai, Gan Jin, Xiaoying Li, Chunwei Dong, Hao Zhang, Bai Yang, Haiming Xie, Haizhu Sun
A novel two-step solution approach is put forward to design a unique three dimensional (3D) porous ZnO-SnS p-n heterojunction under mild conditions. This special 3D structure is induced via flower-like ZnO in which SnS serves as an efficient photosensitizer to improve the light harvesting across the whole visible range. A profound investigation of the mechanism shows that this 3D porous ZnO-SnS material effectively integrates the large surface area and high redox potential of ZnO, and wide visible-light harvesting of SnS, which largely promotes the transfer and separation rate of carriers...
June 14, 2017: Physical Chemistry Chemical Physics: PCCP
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