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21.
Photocatalytic Water Oxidation by a Pyrochlore Oxide upon Irradiation with Visible Light: Rhodium Substitution Into Yttrium Titanate
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Borbala Kiss Dr. Christophe Didier Timothy Johnson Dr. Troy D. Manning Dr. Matthew S. Dyer Dr. Alexander J. Cowan Dr. John B. Claridge Prof. James R. Darwent Prof. Matthew J. Rosseinsky 《Angewandte Chemie (International ed. in English)》2014,53(52):14480-14484
A stable visible‐light‐driven photocatalyst (λ≥450 nm) for water oxidation is reported. Rhodium substitution into the pyrochlore Y2Ti2O7 is demonstrated by monitoring Vegard′s law evolution of the unit‐cell parameters with changing rhodium content, to a maximum content of 3 % dopant. Substitution renders the solid solutions visible‐light active. The overall rate of oxygen evolution is comparable to WO3 but with superior light‐harvesting and surface‐area‐normalized turnover rates, making Y2Ti1.94Rh0.06O7 an excellent candidate for use in a Z‐scheme water‐splitting system. 相似文献
22.
Nathan J. Oldenhuis K. Peter Qin Shu Wang Hong-Zhou Ye Eric A. Alt Adam P. Willard Troy Van Voorhis Stephen L. Craig Prof. Jeremiah A. Johnson 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(7):2806-2814
Photoresponsive materials that change in response to light have been studied for a range of applications. These materials are often metastable during irradiation, returning to their pre-irradiated state after removal of the light source. Herein, we report a polymer gel comprising poly(ethylene glycol) star polymers linked by Cu24L24 metal–organic cages/polyhedra (MOCs) with coumarin ligands. In the presence of UV light, a photosensitizer, and a hydrogen donor, this “polyMOC” material can be reversibly switched between CuII, CuI, and Cu0. The instability of the MOC junctions in the CuI and Cu0 states leads to network disassembly, forming CuI/Cu0 solutions, respectively, that are stable until re-oxidation to CuII and supramolecular gelation. This reversible disassembly of the polyMOC network can occur in the presence of a fixed covalent second network generated in situ by copper-catalyzed azide-alkyne cycloaddition (CuAAC), providing interpenetrating supramolecular and covalent networks. 相似文献
23.
Nolan M. Gallagher Hong-Zhou Ye Shuting Feng Jeffrey Lopez Yun Guang Zhu Troy Van Voorhis Yang Shao-Horn Jeremiah A. Johnson 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(10):3980-3983
We present the discovery of a novel radical cation formed through one-electron oxidation of an N-heterocyclic carbene–carbodiimide (NHC–CDI) zwitterionic adduct. This compound possesses a distonic electronic structure (spatially separate spin and charge regions) and displays persistence under ambient conditions. We demonstrate its application in a redox-flow battery exhibiting minimal voltage hysteresis, a flat voltage plateau, high Coulombic efficiency, and no performance decay for at least 100 cycles. The chemical tunability of NHCs and CDIs suggests that this approach could provide a general entry to redox-active NHC–CDI adducts and their persistent radical ions for various applications. 相似文献
24.
Nathan J. Oldenhuis K. Peter Qin Shu Wang Hong‐Zhou Ye Eric A. Alt Adam P. Willard Troy Van Voorhis Stephen L. Craig Jeremiah A. Johnson 《Angewandte Chemie (International ed. in English)》2020,59(7):2784-2792
Photoresponsive materials that change in response to light have been studied for a range of applications. These materials are often metastable during irradiation, returning to their pre‐irradiated state after removal of the light source. Herein, we report a polymer gel comprising poly(ethylene glycol) star polymers linked by Cu24L24 metal–organic cages/polyhedra (MOCs) with coumarin ligands. In the presence of UV light, a photosensitizer, and a hydrogen donor, this “polyMOC” material can be reversibly switched between CuII, CuI, and Cu0. The instability of the MOC junctions in the CuI and Cu0 states leads to network disassembly, forming CuI/Cu0 solutions, respectively, that are stable until re‐oxidation to CuII and supramolecular gelation. This reversible disassembly of the polyMOC network can occur in the presence of a fixed covalent second network generated in situ by copper‐catalyzed azide‐alkyne cycloaddition (CuAAC), providing interpenetrating supramolecular and covalent networks. 相似文献
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26.
We investigate mixing in a viscoelastic and shear-thinning fluid-a very common combination in polymers and suspensions. We find that competition between elastic and viscous forces generates self-similar mixing, lobe transport, and other characteristics of chaos. The mechanism by which chaos is produced is evaluated both in experiments and in a simple model. We find that chaotic flow is generated by spontaneous oscillations, the magnitude and frequency of which govern the extent of chaos and mixing. 相似文献
27.
We report the spontaneous emergence of a doubly periodic train of sedimented knolls in a dense suspension. These solidified knolls rise out of, and coexist alongside, a sea of freely flowing liquid in a slowly rotating horizontal bottle. We apply a variable viscosity model that permits simultaneous analysis of fluidlike and solidlike behaviors that are ubiquitous in a variety of sedimenting flows. The model generates qualitative agreement with experiments, and produces new insights into mechanisms by which sedimented structures form. 相似文献
28.
Background
Growth cone migratory patterns show evidence of both deterministic and stochastic search modes. 相似文献29.
[reaction: see text] The title technique is a convenient and powerful method for directly monitoring or assaying any reaction mixture or reagent solution. Examples of some common processes (Fischer esterification, lithiation, butyllithium/THF compatibility, olefin metathesis, and a quantification assay), each interrogated in its native solvent, are presented. The spectral data are easy to acquire, and the information content makes a compelling case for routine use of No-D NMR spectroscopy. 相似文献
30.
We report on the novel application of nanoscratch characterization to provide insight into the plasticity mechanisms responsible for the behaviour of composites. Accordingly, we conduct deformation characterization with nanoscratch testing (DCNT) to study the deformation behaviour of two B4C reinforced ultrafine grained Al alloy tri-modal composites with average B4C particle sizes of ~1–6?μm and ~500?nm, respectively. To highlight the type of mechanistic information revealed in a DCNT study of composites, we concentrate on the influence of B4C particle size on deformation mechanisms. 相似文献