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24 Mar 16:03

Stable water oxidation by NiOx-coated photoanodes [Chemistry]

by Sun, K., Saadi, F. H., Lichterman, M. F., Hale, W. G., Wang, H.-P., Zhou, X., Plymale, N. T., Omelchenko, S. T., He, J.-H., Papadantonakis, K. M., Brunschwig, B. S., Lewis, N. S.
Reactively sputtered nickel oxide (NiOx) films provide transparent, antireflective, electrically conductive, chemically stable coatings that also are highly active electrocatalysts for the oxidation of water to O2(g). These NiOx coatings provide protective layers on a variety of technologically important semiconducting photoanodes, including textured crystalline Si passivated by amorphous silicon, crystalline...
24 Mar 16:03

Solar electricity supply isolines [Sustainability Science]

by Grossmann, W., Grossmann, I., Steininger, K. W.
The recent sharp drop in the cost of photovoltaic (PV) electricity generation accompanied by globally rapidly increasing investment in PV plants calls for new planning and management tools for large-scale distributed solar networks. Of major importance are methods to overcome intermittency of solar electricity, i.e., to provide dispatchable electricity at...
07 Apr 16:02

Criticality of metals and metalloids [Sustainability Science]

by Graedel, T. E., Harper, E. M., Nassar, N. T., Nuss, P., Reck, B. K.
Imbalances between metal supply and demand, real or anticipated, have inspired the concept of metal criticality. We here characterize the criticality of 62 metals and metalloids in a 3D “criticality space” consisting of supply risk, environmental implications, and vulnerability to supply restriction. Contributing factors that lead to extreme values include...
02 Apr 21:19

[Feature] Deepwater Horizon: After the oil

by Warren Cornwall
Five years after the worst accidental marine oil spill ever, scientists are untangling how the explosion of the Deepwater Horizon oil rig has left its mark on the Gulf of Mexico. In the Louisiana marshlands, they are finding signs of continued damage and remarkable resilience. Although oil is visible only in spots, toxic residues could linger for decades. Organisms from bacteria to dolphins show signs of the oil's effects. Yet fish appear to be flourishing, brown pelican numbers have remained steady, and insects seem to be on the rebound. Scientists wonder whether the worst has passed, or surprises lie ahead. Author: Warren Cornwall
09 Apr 18:01

[Editors' Choice] How smoking makes infection worse

by Kristen L. Mueller
Author: Kristen L. Mueller
25 Mar 15:10

Activation of Water in Titanium Dioxide Photocatalysis by Formation of Surface Hydrogen Bonds: An In Situ IR Spectroscopy Study

by Hua Sheng, Hongna Zhang, Wenjing Song, Hongwei Ji, Wanhong Ma, Chuncheng Chen, Jincai Zhao

Abstract

The hole-driving oxidation of titanium-coordinated water molecules on the surface of TiO2 is both thermodynamically and kinetically unfavorable. By avoiding the direct coordinative adsorption of water molecules to the surface Ti sites, the water can be activated to realize its oxidation. When TiO2 surface is covered by the H-bonding acceptor F, the first-layer water adsorption mode is switched from Ti coordination to a dual H-bonding adsorption on adjacent surface F sites. Detailed in situ IR spectroscopy and isotope-labeling studies reveal that the adsorbed water molecules by dual H-bonding can be oxidized to O2 even in the absence of any electron scavengers. Combined with theoretical calculations, it is proposed that the formation of the dual H-bonding structure can not only enable the hole transfer to the water molecules thermodynamically, but also facilitate kinetically the cleavage of O[BOND]H bonds by proton-coupled electron transfer process during water oxidation.

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Switching the water adsorption mode on TiO2 to dual H-bonding by the presence of fluorine atoms at the surface not only thermodynamically enables the hole transfer to the water molecules, but also facilitates the proton-coupled electron transfer during water oxidation. This phenomenon is established by IR spectroscopy studies and calculations.

27 Mar 09:50

A Metal-Free N-Annulated Thienocyclopentaperylene Dye: Power Conversion Efficiency of 12 % for Dye-Sensitized Solar Cells

by Zhaoyang Yao, Min Zhang, Renzhi Li, Lin Yang, Yongna Qiao, Peng Wang

Abstract

Reported are two highly efficient metal-free perylene dyes featuring N-annulated thienobenzoperylene (NTBP) and N-annulated thienocyclopentaperylene (NTCP), which are coplanar polycyclic aromatic hydrocarbons. Without the use of any coadsorbate, the metal-free organic dye derived from the NTCP segment was used for a dye-sensitized solar cell which attained a power conversion efficiency of 12 % under an irradiance of 100 mW cm−2, simulated air mass global (AM1.5G) sunlight.

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Power trip: A perylene dye derived from N-annulated thienocyclopentaperylene, which is characterized by a low-energy gap and a high electron injection yield, was synthesized for dye-sensitized solar cells. A high power conversion efficiency of 12 %, at an irradiance of the AM1.5G sunlight, was achieved. This efficiency is the highest achieved thus far by using just a metal-free organic dye.

30 Mar 00:00

An allosteric photoredox catalyst inspired by photosynthetic machinery

by Alejo M. Lifschitz

Article

Photosynthetic systems regulate light harvesting via structural and electronic control of antenna proteins. Here, the authors report a light-harvesting antenna/reaction centre mimic that can be allosterically regulated using mild and redox-inactive inputs, via a coordination framework with hemilabile ligands.

Nature Communications doi: 10.1038/ncomms7541

Authors: Alejo M. Lifschitz, Ryan M. Young, Jose Mendez-Arroyo, Charlotte L. Stern, C. Michael McGuirk, Michael R. Wasielewski, Chad A. Mirkin

30 Mar 00:00

Electride support boosts nitrogen dissociation over ruthenium catalyst and shifts the bottleneck in ammonia synthesis

by Masaaki Kitano

Article

Development of catalysts that enhance dissociation of the nitrogen–nitrogen triple bond will reduce costs of ammonia production. Here, the authors study ammonia synthesis over a ruthenium loaded electride catalyst and show that the rate-determining step is shifted to nitrogen–hydrogen bond formation.

Nature Communications doi: 10.1038/ncomms7731

Authors: Masaaki Kitano, Shinji Kanbara, Yasunori Inoue, Navaratnarajah Kuganathan, Peter V. Sushko, Toshiharu Yokoyama, Michikazu Hara, Hideo Hosono

20 Mar 11:16

Role of Hot Electrons and Metal–Oxide Interfaces in Surface Chemistry and Catalytic Reactions

by Jeong Young Park, L. Robert Baker and Gabor A. Somorjai

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Chemical Reviews
DOI: 10.1021/cr400311p
20 Mar 17:29

Activation and Deactivation of a Robust Immobilized Cp*Ir-Transfer Hydrogenation Catalyst: A Multielement in Situ X-ray Absorption Spectroscopy Study

by Grant J. Sherborne, Michael R. Chapman, A. John Blacker, Richard A. Bourne, Thomas W. Chamberlain, Benjamin D. Crossley, Stephanie J. Lucas, Patrick C. McGowan, Mark A. Newton, Thomas E. O Screen, Paul Thompson, Charlotte E. Willans and Bao N. Nguyen

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Journal of the American Chemical Society
DOI: 10.1021/ja512868a
20 Mar 22:30

Mesoporous Carbon Nitride-Tungsten Oxide Composites for Enhanced Photocatalytic Hydrogen Evolution

by Kamalakannan Kailasam, Anna Fischer, Guigang Zhang, Jinshui Zhang, Michael Schwarze, Marc Schröder, Xinchen Wang, Reinhard Schomäcker, Arne Thomas

Abstract

Composites of mesoporous polymeric carbon nitride and tungsten(VI) oxide show very high photocatalytic activity for the evolution of hydrogen from water under visible light and in the presence of sacrificial electron donors. Already addition of very small amounts of WO3 yields up to a twofold increase in the efficiency when compared to bulk carbon nitrides and their composites and more notably even to the best reported mesoporous carbon nitride-based photocatalytic materials. The higher activity can be attributed to the high surface area and synergetic effect of the carbon nitrides and the WO3 resulting in improved charge separation through a photocatalytic solid-state Z-scheme mechanism.

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CN/WO3 composites for enhanced H2 evolution: Mesoporous CN/WO3 composites prepared by a simple dispersion method are efficient photocatalysts for enhanced hydrogen production from water. Compared to other nonporous composites based on carbon nitrides, a twofold increase in activity is observed, which is attributed to the high surface area and efficient solid-state Z-scheme-induced charge separation in these composites.

20 Mar 16:10

Air-Stable (CAAC)CuCl and (CAAC)CuBH4 Complexes as Catalysts for the Hydrolytic Dehydrogenation of BH3NH3

by Xingbang Hu, Michèle Soleilhavoup, Mohand Melaimi, Jiaxiang Chu, Guy Bertrand

Abstract

The first stable copper borohydride complex [(CAAC)CuBH4] [CAAC=cyclic(alkyl)(amino)carbene] bearing a single monodentate ligand was prepared by addition of NaBH4 or BH3NH3 to the corresponding [(CAAC)CuCl] complex. Both complexes are air-stable and promote the catalytic hydrolytic dehydrogenation of ammonia borane. The amount of hydrogen released reaches 2.8 H2/BH3NH3 with a turnover frequency of 8400 molinline image molcat−1 h−1 at 25 °C. In a fifteen-cycle experiment, the catalyst was reused without any loss of efficiency.

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Copper works! [(CAAC)CuCl] reacts with both NaBH4 and BH3NH3 to afford [(CAAC)CuBH4] as a thermally and air-stable complex. Both complexes efficiently promote the hydrolytic dehydrogenation of ammonia borane at room temperature, with a turnover frequency of up to 8400 molinline image molcat−1 h−1. In addition, these air-stable catalysts are readily recyclable. CAAC=cyclic (alkyl)(amino)carbene.

20 Mar 16:50

Semiconductor Photocatalysis: Principles and Applications. By Horst Kisch

by Horst Hennig
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Wiley-VCH, Weinheim 2015. 264 pp., € 126.00.—ISBN 978-3527335534

20 Mar 16:50

Widening Synthesis Bottlenecks: Realization of Ultrafast and Continuous-Flow Synthesis of High-Silica Zeolite SSZ-13 for NOx Removal

by Zhendong Liu, Toru Wakihara, Kazunori Oshima, Daisuke Nishioka, Yuusuke Hotta, Shanmugam P. Elangovan, Yutaka Yanaba, Takeshi Yoshikawa, Watcharop Chaikittisilp, Takeshi Matsuo, Takahiko Takewaki, Tatsuya Okubo

Abstract

Characteristics of zeolite formation, such as being kinetically slow and thermodynamically metastable, are the main bottlenecks that obstruct a fast zeolite synthesis. We present an ultrafast route, the first of its kind, to synthesize high-silica zeolite SSZ-13 in 10 min, instead of the several days usually required. Fast heating in a tubular reactor helps avoid thermal lag, and the synergistic effect of addition of a SSZ-13 seed, choice of the proper aluminum source, and employment of high temperature prompted the crystallization. Thanks to the ultra-short period of synthesis, we established a continuous-flow preparation of SSZ-13. The fast-synthesized SSZ-13, after copper-ion exchange, exhibits outstanding performance in the ammonia selective catalytic reduction (NH3-SCR) of nitrogen oxides (NOx), showing it to be a superior catalyst for NOx removal. Our results indicate that the formation of high-silica zeolites can be extremely fast if bottlenecks are effectively widened.

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Bottle opener: SSZ-13 is a zeolite commercialized as a catalyst to remove nitrogen oxides (NOx). However, its long synthesis time is one of the biggest barriers to large-scale production. An ultrafast synthesis route now allows SSZ-13 to be synthesized in 10 min and thus facilitates continuous preparation of SSZ-13. The fast-synthesized SSZ-13 exhibits outstanding performance for the NOx removal.

20 Mar 22:30

SBA-15-Oxynitrides as a Solid-Base Catalyst: Effect of Nitridation Temperature on Catalytic Activity

by Baljeet Singh, Kaustubh R. Mote, C. S. Gopinath, P. K. Madhu, Vivek Polshettiwar

Abstract

Solid bases, such as SBA-15-oxynitrides, have attracted considerable interest for potential applications as catalysts in important industrial processes. Reported herein is that by simply tuning the temperature of nitridation (ammonolysis), the catalytic activity of these solid bases can be enhanced. Solid-state NMR spectroscopy and XPS studies provided the reasoning behind this change in activity.

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Oxynitride solid: Solid bases, such as SBA-15-oxynitrides, have attracted considerable interest for potential applications as catalysts in important industrial processes. Reported here is that tuning the temperature of nitridation (ammonolysis) leads to enhanced catalytic activity of these solid bases. Detailed studies are discussed to explain this change in activity.

20 Mar 00:00

Transfer hydrogenation catalysis in cells as a new approach to anticancer drug design

by Joan J. Soldevila-Barreda

Article

Organometallic complexes are effective hydrogenation catalysts for organic reactions. Here the authors report for the first time that transfer hydrogenation catalysis can take place inside the cell and could be used as a novel anticancer strategy.

Nature Communications doi: 10.1038/ncomms7582

Authors: Joan J. Soldevila-Barreda, Isolda Romero-Canelón, Abraha Habtemariam, Peter J. Sadler

23 Mar 00:00

Efficient hole-blocking layer-free planar halide perovskite thin-film solar cells

by Weijun Ke

Article

Lead halide perovskite solar cells use hole-blocking layers to allow a separate collection of positive and negative charge carriers and to achieve high-operation voltages. Here, the authors demonstrate efficient lead halide perovskite solar cells that avoid using this extra layer.

Nature Communications doi: 10.1038/ncomms7700

Authors: Weijun Ke, Guojia Fang, Jiawei Wan, Hong Tao, Qin Liu, Liangbin Xiong, Pingli Qin, Jing Wang, Hongwei Lei, Guang Yang, Minchao Qin, Xingzhong Zhao, Yanfa Yan

16 Mar 14:02

Base-Free Methanol Dehydrogenation Using a Pincer-Supported Iron Compound and Lewis Acid Co-catalyst

by Elizabeth A. Bielinski, Moritz Förster, Yuanyuan Zhang, Wesley H. Bernskoetter, Nilay Hazari and Max C. Holthausen

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ACS Catalysis
DOI: 10.1021/acscatal.5b00137
16 Mar 14:02

Combining Low-Pressure CO2 Capture and Hydrogenation To Form Methanol

by Julia R. Khusnutdinova, Jai Anand Garg and David Milstein

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ACS Catalysis
DOI: 10.1021/acscatal.5b00194
17 Mar 14:43

BODIPY-Derived Photoremovable Protecting Groups Unmasked with Green Light

by Pratik P. Goswami, Aleem Syed, Christie L. Beck, Toshia R. Albright, Kaitlyn M. Mahoney, Ryan Unash, Emily A. Smith and Arthur H. Winter

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Journal of the American Chemical Society
DOI: 10.1021/jacs.5b01297
17 Mar 20:20

Tunable Photochromism in the Robust Dithienylethene-Containing Phospholes: Design, Synthesis, Characterization, Electrochemistry, Photophysics, and Photochromic Studies

by Jacky Chi-Hung Chan, Hok-Lai Wong, Wing-Tak Wong, Vivian Wing-Wah Yam

Abstract

A series of dithienylethene-containing phosphole derivatives has been designed, synthesized and characterized. One of the compounds has been characterized by X-ray crystallography. Upon photoexcitation, the compounds exhibit drastic color changes, ascribed to the reversible photochromic behavior. Their photochromic, photophysical and electrochemical properties have been studied. They show photochromic reactivities with high photocyclization quantum yields. Their photophysical and photochromic properties are found to be facilely tuned in this system by substitution at the phosphole backbone, as well as variation on the extent of π-conjugation of the phosphole backbone. Some selected compounds have been demonstrated to exhibit photochromic properties in polymethylmethacrylate (PMMA) films.

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Robust photoswitch: A new series of robust dithienylethene-containing phosphole derivatives has been synthesized (see figure); their photophysical and photochromic properties are found to be readily tuned by simple modifications at the phosphorus center, substitution at the phosphole backbone, as well as variation on the extent of π-conjugation of the phosphole backbone. Both the open and closed forms of the phosphole compounds have good thermal stability in benzene solution and in PMMA film.

18 Mar 10:07

Frontispiece: A Simple Iridicycle Catalyst for Efficient Transfer Hydrogenation of N-Heterocycles in Water

by Dinesh Talwar, Ho Yin Li, Emma Durham, Jianliang Xiao
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Transfer hydrogenation Transfer hydrogenation is a simple safe way for reduction reactions and using water as a solvent has the additional benefit of being “green”. In their Full paper on page 5370 ff., J. Xiao et al. report that a cyclometalated iridium complex catalyzes the transfer hydrogenation of various nitrogen heterocycles in an aqueous solution of formate under mild conditions. The catalyst shows excellent functional-group compatibility and high turnover number, with loadings as low as 0.01 mol % being feasible. A mechanistic study of quinoline reduction suggests that the reaction proceeds via both 1,2- and 1,4-addition pathways, with the catalytic turnover limited by hydride transfer.

19 Mar 12:42

Electrochemical and Spectroelectrochemical Studies of Diphosphorylated Metalloporphyrins. Generation of a Phlorin Anion Product

by Yuanyuan Fang, Yulia G. Gorbunova, Ping Chen, Xiaoqin Jiang, Machima Manowong, Anna A. Sinelshchikova, Yulia Yu. Enakieva, Alexander G. Martynov, Aslan Yu. Tsivadze, Alla Bessmertnykh-Lemeune, Christine Stern, Roger Guilard and Karl M. Kadish

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Inorganic Chemistry
DOI: 10.1021/acs.inorgchem.5b00067
19 Mar 13:24

Hydroboration of Carbon Dioxide Using Ambiphilic Phosphine–Borane Catalysts: On the Role of the Formaldehyde Adduct

by Richard Declercq, Ghenwa Bouhadir, Didier Bourissou, Marc-André Légaré, Marc-André Courtemanche, Karine Syrine Nahi, Nicolas Bouchard, Frédéric-Georges Fontaine and Laurent Maron

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ACS Catalysis
DOI: 10.1021/acscatal.5b00189
19 Mar 14:09

Chemoenzymatic Dynamic Kinetic Resolution: A Powerful Tool for the Preparation of Enantiomerically Pure Alcohols and Amines

by Oscar Verho and Jan-E. Bäckvall

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Journal of the American Chemical Society
DOI: 10.1021/jacs.5b01031
19 Mar 19:33

Ancillary Ligand Control of Electronic Structure in o-Benzoquinonediimine-Ruthenium Complex Redox Series: Structures, Electron Paramagnetic Resonance (EPR), and Ultraviolet−Visible−Near-Infrared (UV-vis-NIR) Spectroelectrochemistry

by Ankita Das, Prabir Ghosh, Sebastian Plebst, Brigitte Schwederski, Shaikh M. Mobin, Wolfgang Kaim and Goutam Kumar Lahiri

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Inorganic Chemistry
DOI: 10.1021/ic503070j
19 Mar 18:54

In Situ Formation of Cobalt Oxide Nanocubanes as Efficient Oxygen Evolution Catalysts

by Gregory S. Hutchings, Yan Zhang, Jian Li, Bryan T. Yonemoto, Xinggui Zhou, Kake Zhu and Feng Jiao

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Journal of the American Chemical Society
DOI: 10.1021/jacs.5b01006
19 Mar 19:53

[Editors' Choice] Silver's salty twist on water splitting

by Jake Yeston
Author: Jake Yeston
17 Mar 20:50

Progress on All Ends for Carbon–Carbon Bond Formation through Photoredox Catalysis

by Miguel Peña-López, Alonso Rosas-Hernández, Matthias Beller
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Dual role for catalysts: Novel routes for the generation of asymmetric stereocenters using photoredox catalysis were recently developed. Different chiral catalytic systems allowed new C[BOND]C bonds to form in good yields and enantioselectivities using a mild methodology in which light is used as the energy source.