共查询到20条相似文献,搜索用时 15 毫秒
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Won‐Sik Han Kyung‐Ryang Wee Hyun‐Young Kim Prof. Chyongjin Pac Yu Nabetani Daisuke Yamamoto Tetsuya Shimada Prof. Haruo Inoue Heesung Choi Prof. Kyeongjae Cho Prof. Sang Ook Kang 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(48):15368-15381
Visible‐light‐driven H2 evolution based on Dye/TiO2/Pt hybrid photocatalysts was investigated for a series of (E)‐3‐(5′‐{4‐[bis(4‐R1‐phenyl)amino]phenyl}‐4,4′‐(R2)2‐2,2′‐bithiophen‐5‐yl)‐2‐cyanoacrylic acid dyes. Efficiencies of hydrogen evolution from aqueous suspensions in the presence of ethylenediaminetetraacetic acid as electron donor under illumination at λ>420 nm were found to considerably depend on the hydrophilic character of R1, varying in the order MOD (R1=CH3OCH2, R2=H)≈ MO4D (R1=R2=CH3OCH2)> HD (R1=R2=H)> PD (R1=C3H7, R2=H). In the case of MOD /TiO2/Pt, the apparent quantum yield for photocatalyzed H2 generation at 436 nm was 0.27±0.03. Transient absorption measurements for MOD ‐ or PD ‐grafted transparent films of TiO2 nanoparticles dipped into water at pH 3 commonly revealed ultrafast formation (<100 fs) of the dye radical cation (Dye.+) followed by multicomponent decays, which involve minor fast decays (<5 ps) almost independent of R1 and major slower decays with significant differences between the two samples: 1) the early decay of the major components for MOD is about 2.5 times slower than that for PD and 2) a redshift of the spectrum occurred for MOD with a time constant of 17 ps, but not for PD . The substituent effects on H2 generation as well as on transient behavior have been discussed in terms substituent‐dependent charge recombination (CR) of Dye.+ with electrons in bulk, inner‐trap, and/or interstitial‐trap states, arising from different solvent reorganization. 相似文献
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Dr. Ling Zhang Zhongkang Han Prof. Wenzhong Wang Xiaoman Li Yang Su Dong Jiang Dr. Xiaoling Lei Dr. Songmei Sun 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(50):18089-18094
A suitable photocatalyst for overall water splitting has been produced by overcoming the disadvantage of the band structure in bulk BiOCl by reducing the thickness to the quantum scale. The ultrathin BiOCl nanosheets with surface/subsurface defects realized the solar‐driven pure water splitting in the absence of any co‐catalysts or sacrificial agent. These surface defects cannot only shift both the valence band and conduction band upwards for band‐gap narrowing but also promote charge‐carrier separation. The amount of defects in the outer layer surface of BiOCl results in an enhancement of carrier density and faster charge transport. First‐principles calculations provide clear evidence that the formation of surface oxygen vacancies is easier for the ultrathin BiOCl nanosheets than for its thicker counterpart. These defects can serve as active sites to effectively adsorb and dissociate H2O molecules, resulting in a significantly improved water‐splitting performance. 相似文献
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Wataru Kurashige Yutaro Mori Shuhei Ozaki Masanobu Kawachi Sakiat Hossain Tokuhisa Kawawaki Cameron J. Shearer Akihide Iwase Gregory F. Metha Seiji Yamazoe Akihiko Kudo Yuichi Negishi 《Angewandte Chemie (International ed. in English)》2020,59(18):7076-7082
The activity of many water‐splitting photocatalysts could be improved by the use of RhIII–CrIII mixed oxide (Rh2?xCrxO3) particles as cocatalysts. Although further improvement of water‐splitting activity could be achieved if the size of the Rh2?xCrxO3 particles was decreased further, it is difficult to load ultrafine (<2 nm) Rh2?xCrxO3 particles onto a photocatalyst by using conventional loading methods. In this study, a new loading method was successfully established and was used to load Rh2?xCrxO3 particles with a size of approximately 1.3 nm and a narrow size distribution onto a BaLa4Ti4O15 photocatalyst. The obtained photocatalyst exhibited an apparent quantum yield of 16 %, which is the highest achieved for BaLa4Ti4O15 to date. Thus, the developed loading technique of Rh2?xCrxO3 particles is extremely effective at improving the activity of the water‐splitting photocatalyst BaLa4Ti4O15. This method is expected to be extended to other advanced water‐splitting photocatalysts to achieve higher quantum yields. 相似文献
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A Heteroleptic Push–Pull Substituted Iron(II) Bis(tridentate) Complex with Low‐Energy Charge‐Transfer States 下载免费PDF全文
Andreas K. C. Mengel Dr. Christoph Förster Dr. Aaron Breivogel Katharina Mack Julian R. Ochsmann Dr. Frédéric Laquai Dr. Vadim Ksenofontov Prof. Dr. Katja Heinze 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(2):704-714
A heteroleptic iron(II) complex [Fe(dcpp)(ddpd)]2+ with a strongly electron‐withdrawing ligand (dcpp, 2,6‐bis(2‐carboxypyridyl)pyridine) and a strongly electron‐donating tridentate tripyridine ligand (ddpd, N,N′‐dimethyl‐N,N′‐dipyridine‐2‐yl‐pyridine‐2,6‐diamine) is reported. Both ligands form six‐membered chelate rings with the iron center, inducing a strong ligand field. This results in a high‐energy, high‐spin state (5T2, (t2g)4(eg*)2) and a low‐spin ground state (1A1, (t2g)6(eg*)0). The intermediate triplet spin state (3T1, (t2g)5(eg*)1) is suggested to be between these states on the basis of the rapid dynamics after photoexcitation. The low‐energy π* orbitals of dcpp allow low‐energy MLCT absorption plus additional low‐energy LL′CT absorptions from ddpd to dcpp. The directional charge‐transfer character is probed by electrochemical and optical analyses, Mößbauer spectroscopy, and EPR spectroscopy of the adjacent redox states [Fe(dcpp)(ddpd)]3+ and [Fe(dcpp)(ddpd)]+, augmented by density functional calculations. The combined effect of push–pull substitution and the strong ligand field paves the way for long‐lived charge‐transfer states in iron(II) complexes. 相似文献
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A Three‐Component Assembly Promoted by Boronic Acids Delivers a Modular Fluorophore Platform (BASHY Dyes)
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Fábio M. F. Santos Dr. João N. Rosa Dr. Nuno R. Candeias Cátia Parente Carvalho Ana I. Matos Ana E. Ventura Dr. Helena F. Florindo Dr. Liana C. Silva Dr. Uwe Pischel Dr. Pedro M. P. Gois 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(5):1631-1637
The modular assembly of boronic acids with Schiff‐base ligands enabled the construction of innovative fluorescent dyes [boronic acid salicylidenehydrazone (BASHY)] with suitable structural and photophysical properties for live cell bioimaging applications. This reaction enabled the straightforward synthesis (yields up to 99 %) of structurally diverse and photostable dyes that exhibit a polarity‐sensitive green‐to‐yellow emission with high quantum yields of up to 0.6 in nonpolar environments. These dyes displayed a high brightness (up to 54 000 m ?1 cm?1). The promising structural and fluorescence properties of BASHY dyes fostered the preparation of non‐cytotoxic, stable, and highly fluorescent poly(lactide‐co‐glycolide) nanoparticles that were effectively internalized by dendritic cells. The dyes were also shown to selectively stain lipid droplets in HeLa cells, without inducing any appreciable cytotoxicity or competing plasma membrane labeling; this confirmed their potential as fluorescent stains. 相似文献
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Wenrui Lin Boyang Zhang Kaiwei Liu Dr. Jifang Zhang Jiaming Wang Prof. Guijun Ma 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(51):e202201169
Photoelectrochemical (PEC) performance of WO3 photoanodes for water splitting is heavily influenced by the orientation of crystal facets. In this work, mono-particle-layer electrodes, assembled by particulate WO3 square plates with highly uniform alignment along the (002) facet, improved PEC water oxidation kinetics and stability. Photo-deposition of Au along the cracks formed on the surface of the plates, which are the edges of {110} facets, was found to further enhance electron collection efficiency. Combination of these two strategies allowed the facet-engineered WO3 electrode to produce significantly higher efficiencies in charge separation and transfer than the electrode prepared without facet orientation. This work has provided a facile route for fabricating a structurally designed WO3 photoelectrode, which is also applicable to other regularly shaped semiconductor photocatalysts with anisotropic charge migration. 相似文献
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Mengmeng Zhang Dr. Jiajun Wang Hui Xue Dr. Jinfeng Zhang Prof. Dr. Shengjie Peng Dr. Xiaopeng Han Prof. Dr. Yida Deng Prof. Dr. Wenbin Hu 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(42):18621-18625
Cu2O is a typical photoelectrocatalyst for sustainable hydrogen production, while the fast charge recombination hinders its further development. Herein, Ni2+ cations have been doped into a Cu2O lattice (named as Ni-Cu2O) by a simple hydrothermal method and act as electron traps. Theoretical results predict that the Ni dopants produce an acceptor impurity level and lower the energy barrier of hydrogen evolution. Photoelectrochemical (PEC) measurements demonstrate that Ni-Cu2O exhibits a photocurrent density of 0.83 mA cm−2, which is 1.34 times higher than that of Cu2O. And the photostability has been enhanced by 7.81 times. Moreover, characterizations confirm the enhanced light-harvesting, facilitated charge separation and transfer, prolonged charge lifetime, and increased carrier concentration of Ni-Cu2O. This work provides deep insight into how acceptor-doping modifies the electronic structure and optimizes the PEC process. 相似文献
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Gaurangi Gogoi Ching Thian Moi Anindya Sundar Patra Devipriya Gogoi Peela Nageswara Rao Mohammad Qureshi 《化学:亚洲杂志》2019,14(24):4607-4615
One of the major limiting factors for efficient photoelectrochemical water oxidation is the fast recombination kinetics of photogenerated charge carriers. Herein, we propose a model system that utilizes ZnIn2S4 and hierarchical VS2 microflowers for efficient charge separation through a Z‐scheme pathway, without the need for an electron mediator. An impressive 18‐fold increase in photocurrent was observed for ZnIn2S4–VS2 compared to ZnIn2S4 alone. The charge‐transfer dynamics in the composite were found to follow a Z‐scheme pathway, which resulted in decreased charge recombination and greater accumulation of the surface charge. Furthermore, slow kinetics of the surface reaction in the ZnIn2S4–VS2 composite correlated to an increased surface‐charge capacitance. This feature of the composite material facilitated partial storage of the photogenerated charge carriers (e?/h+) under illumination and dark‐current conditions, thus storing and utilizing solar energy more efficiently. 相似文献
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In Taek Choi Dr. Myung Jong Ju Sang Hyun Song Sang Gyun Kim Dr. Dae Won Cho Prof. Dr. Chan Im Prof. Dr. Hwan Kyu Kim 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(46):15545-15555
The Y‐shaped, low molecular mass, hole‐conductor (HC), acidic coadsorbents 4‐{3,7‐bis[4‐(2‐ethylhexyloxy)phenyl]‐10H‐phenothiazin‐10‐yl}benzoic acid ( PTZ1 ) and 4‐{3,7‐bis[4‐(2‐ethylhexyloxy)phenyl]‐10H‐phenothiazin‐10‐yl}biphenyl‐4‐carboxylic acid ( PTZ2 ) were developed. Owing to their tuned and negative‐shifted HOMO levels (vs. NHE), they were used as HC coadsorbents in dye‐sensitized solar cells (DSSCs) to improve cell performance through desired cascade‐type hole‐transfer processes. Their detailed functions as HC coadsorbents in DSSCs were investigated to obtain evidence for the desired cascade‐type hole‐transfer processes. They have multiple functions, such as preventing π–π stacking of dye molecules, harvesting light of shorter wavelengths, and faster dye regeneration. By using PTZ2 as the tailor‐made HC coadsorbent on the TiO2 surface with the organic dye NKX2677, an extremely high conversion efficiency of 8.95 % was achieved under 100 mW cm?2 AM 1.5G simulated light (short‐circuit current JSC=16.56 mA cm?2, open‐circuit voltage VOC=740 mV, and fill factor of 73 %). Moreover, JSC was increased by 13 %, VOC by 27 % and power‐conversion efficiency by 49 % in comparison to an NKX2677‐based DSSC without an HC coadsorbent. This is due to the HC coadsorbent having a HOMO energy level well matched to that of the NKX‐2677 dye to induce the desired cascade‐type hole‐transfer processes, which are associated with a slower charge recombination, fast dye regeneration, effective screening of liquid electrolytes, and an induced negative shift of the quasi‐Fermi level of the electrode. Thus, this new class of Y‐shaped, low molecular weight, organic, HC coadsorbents based on phenothiazine carboxylic acid derivatives hold promise for highly efficient organic DSSCs. 相似文献
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Jérôme Fortage Dr. Annabelle Scarpaci Dr. Lydie Viau Dr. Yann Pellegrin Dr. Errol Blart Dr. Magnus Falkenström Dr. Leif Hammarström Prof. Inge Asselberghs Ruben Kellens Dr. Wim Libaers Dr. Koen Clays Prof. Mattias P. Eng Dr. Fabrice Odobel Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2009,15(36):9058-9067
We report the synthesis and the characterizations of a novel dyad composed of a zinc porphyrin (ZnP) linked to a gold porphyrin (AuP) through an ethynyl spacer. The UV/Vis absorption spectrum and the electrochemical properties clearly reveal that this dyad exhibits a strong electronic coupling in the ground state as evidenced by shifted redox potentials and the appearance of an intense charge‐transfer band localized at λ=739 nm in dichloromethane. A spectroelectrochemical study of the dyad along with the parent homometallic system (i.e., ZnP–ZnP and AuP–AuP) was undertaken to determine the spectra of the reduced and oxidized porphyrin units. Femtosecond transient absorption spectroscopic analysis showed that the photoexcitation of the heterometallic dyad leads to an ultrafast formation of a charge‐separated state (+ZnP–AuP.) that displays a particularly long lifetime (τ=4 ns in toluene) for such a short separation distance. The molecular orbitals of the dyad were determined by DFT quantum‐chemical calculations. This theoretical study confirms that the observed intense band at λ=739 nm corresponds to an interporphyrin charge‐transfer transition from the HOMO orbital localized on the zinc porphyrin to LUMO orbitals localized on the gold porphyrin. Finally, a Hyper–Rayleigh scattering study shows that the dyad possesses a large first molecular hyperpolarizability coefficient (β=2100×10?30 esu at λ=1064 nm), thus highlighting the valuable nonlinear optical properties of this new type of push–pull porphyrin system. 相似文献
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Jinhong Bi Wei Fang Liuyi Li Jinyun Wang Shijing Liang Yunhui He Minghua Liu Ling Wu 《Macromolecular rapid communications》2015,36(20):1799-1805
Covalent triazine‐based frameworks (CTFs) with a graphene‐like layered morphology have been controllably synthesized by the trifluoromethanesulfonic acid‐catalyzed nitrile trimerization reactions at room temperature via selecting different monomers. Platinum nanoparticles are well dispersed in CTF‐T1, which is ascribed to the synergistic effects of the coordination of triazine moieties and the nanoscale confinement effect of CTFs. CTF‐T1 exhibits excellent photocatalytic activity and stability for H2 evolution in the presence of platinum under visible light irradiation (λ ≥ 420 nm). The activity and stability of CTF‐T1 are comparable to those of g‐C3N4. Importantly, as a result of the tailorable electronic and spatial structures of CTFs that can be achieved through the judicial selection of monomers, CTFs not only show great potential as organic semiconductor for photocatalysis but also may provide a molecular‐level understanding of the inherent heterogeneous photocatalysis.
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Weiben Chen Lei Wang Daize Mo Feng He Zhilin Wen Xiaojun Wu Hangxun Xu Long Chen 《Angewandte Chemie (International ed. in English)》2020,59(39):16902-16909
Two‐dimensional covalent organic frameworks (2D COFs), an emerging class of crystalline porous polymers, have been recognized as a new platform for efficient solar‐to‐hydrogen energy conversion owing to their pre‐designable structures and tailor‐made functions. Herein, we demonstrate that slight modulation of the chemical structure of a typical photoactive 2D COF (Py‐HTP‐BT‐COF) via chlorination (Py‐ClTP‐BT‐COF) and fluorination (Py‐FTP‐BT‐COF) can lead to dramatically enhanced photocatalytic H2 evolution rates (HER=177.50 μmol h?1 with a high apparent quantum efficiency (AQE) of 8.45 % for Py‐ClTP‐BT‐COF). Halogen modulation at the photoactive benzothiadiazole moiety can efficiently suppress charge recombination and significantly reduce the energy barrier associated with the formation of H intermediate species (H*) on polymer surface. Our findings provide new prospects toward design and synthesis of highly active organic photocatalysts toward solar‐to‐chemical energy conversion. 相似文献