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81.
Visible‐Light‐Induced Generation of H2 by Nanocomposites of Few‐Layer TiS2 and TaS2 with CdS Nanoparticles 下载免费PDF全文
Uttam Gupta Bolla Govinda Rao Urmimala Maitra Dr. B. E. Prasad Prof. C. N. R. Rao 《化学:亚洲杂志》2014,9(5):1311-1315
Graphene analogues of TaS2 and TiS2 (3–4 layers), prepared by Li intercalation followed by exfoliation in water, were characterized. Nanocomposites of CdS with few‐layer TiS2 and TaS2 were employed for the visible‐light‐induced H2 evolution reaction (HER). Benzyl alcohol was used as the sacrificial electron donor, which was oxidized to benzaldehyde during the reaction. Few‐layer TiS2 is a semiconductor with a band gap of 0.7 eV, and its nanocomposite with CdS showed an activity of 1000 μmol h?1 g?1. The nanocomposite of few‐layer TaS2, in contrast, gave rise to higher activity of 2320 μmol h?1 g?1, which was attributed to the metallic nature of few‐layer TaS2. The amount of hydrogen evolved after 20 and 16 h for the CdS/TiS2 and CdS/TaS2 nanocomposites was 14833 and 28132 μmol, respectively, with turnover frequencies of 0.24 and 0.57 h?1, respectively. 相似文献
82.
《Journal of Energy Chemistry》2014,23(2):179-184
Facile deposition of a water-splitting catalyst on low-cost electrode materials could be attractive for hydrogen production from water and solar energy conversion. Herein we describe fast electrodeposition of cobalt-based water oxidation catalyst(Co-WOC) on simple graphite electrode for water splitting. The deposition process is quite fast, which reaches a plateau in less than 75 min and the final current density is~1.8 mA/cm2under the applied potential of 1.31 V at pH = 7.0. The scanning electron microscopy(SEM) study shows the formation of nanometer-sized particles(10-100 nm) on the surface of the electrode after only 2 min and micrometer-sized particles(2-5 μm) after 90 min of electrolysis. X-ray photoelectron spectroscopy(XPS) data demonstrate the as-synthesized ex-situ catalyst mainly contains Co2+and Co3+species incorporating a substantial amount of phosphate anions. These experiments suggest that cost-efficient cobalt oxide materials on graphite exhibit alluring ability for water splitting, which might provide a novel method to fabricate low-cost devices for electrochemical energy storage. 相似文献
83.
Hydrogen generated through the photochemical cleavage of water using renewable solar energy is considered to be an environmentally friendly chemical fuel of the future, which neither results in air pollution nor leads to the emission of greenhouse gases. The photocatalytic materials for water cleavage are required to perform at least two fundamental functions: light harvesting of the maximal possible part of the solar energy spectrum and a catalytic function for efficient water decomposition into oxygen and hydrogen. Photocatalytic systems based on colloidal semiconductor nanocrystals offer a number of advantages in comparison with photoelectrochemical cells based on bulk electrodes: (i) a broad range of material types are available; (ii) higher efficiencies are expected due to short distance charge transport; (iii) large surface areas are beneficial for the catalytic processes; (iv) flexibility in fabrication and design which also allows for tuning of the electronic and optical properties by employing quantum confinement effects. The presence of co-catalysts on colloidal semiconductors is an important part of the overall design of the photocatalytic colloidal systems necessary to maximize the water splitting efficiency. This review article discusses the rational choice of colloidal nanoheterostructured materials based on light-harvesting II–VI semiconductor nanocrystals combined with a variety of metal and/or non-metal co-catalysts, with optimized light harvesting, charge separation, and photocatalytic functions. 相似文献
84.
Cobalt‐Embedded Nitrogen‐Rich Carbon Nanotubes Efficiently Catalyze Hydrogen Evolution Reaction at All pH Values 下载免费PDF全文
Dr. Xiaoxin Zou Xiaoxi Huang Dr. Anandarup Goswami Dr. Rafael Silva Dr. Bhaskar R. Sathe Eliška Mikmeková Prof. Tewodros Asefa 《Angewandte Chemie (International ed. in English)》2014,53(17):4372-4376
Despite being technically possible, splitting water to generate hydrogen is still practically unfeasible due mainly to the lack of sustainable and efficient catalysts for the half reactions involved. Herein we report the synthesis of cobalt‐embedded nitrogen‐rich carbon nanotubes (NRCNTs) that 1) can efficiently electrocatalyze the hydrogen evolution reaction (HER) with activities close to that of Pt and 2) function well under acidic, neutral or basic media alike, allowing them to be coupled with the best available oxygen‐evolving catalysts—which also play crucial roles in the overall water‐splitting reaction. The materials are synthesized by a simple, easily scalable synthetic route involving thermal treatment of Co2+‐embedded graphitic carbon nitride derived from inexpensive starting materials (dicyandiamide and CoCl2). The materials’ efficient catalytic activity is mainly attributed to their nitrogen dopants and concomitant structural defects. 相似文献
85.
Large Zero‐Field Splittings of the Ground Spin State Arising from Antisymmetric Exchange Effects in Heterometallic Triangles 下载免费PDF全文
Samantha A. Magee Dr. Stephen Sproules Dr. Anne‐Laure Barra Dr. Grigore A. Timco Nicholas F. Chilton Prof. David Collison Prof. Richard E. P. Winpenny Prof. Eric J. L. McInnes 《Angewandte Chemie (International ed. in English)》2014,53(21):5310-5313
[Ru2Mn(O)(O2CtBu)6(py)3] has an S=5/2 ground state with a very large zero‐field splitting (ZFS) of D=2.9 cm?1, as characterized by EPR spectroscopy at 4–330 GHz. This is far too large to be due to the MnII ion (D <0.2 cm?1), as shown from the {Fe2Mn} analogue, but can be modeled by antisymmetric exchange effects. 相似文献
86.
Highly Active Electrocatalysis of the Hydrogen Evolution Reaction by Cobalt Phosphide Nanoparticles 下载免费PDF全文
Eric J. Popczun Carlos G. Read Christopher W. Roske Prof. Nathan S. Lewis Prof. Raymond E. Schaak 《Angewandte Chemie (International ed. in English)》2014,53(21):5427-5430
Nanoparticles of cobalt phosphide, CoP, have been prepared and evaluated as electrocatalysts for the hydrogen evolution reaction (HER) under strongly acidic conditions (0.50 M H2SO4, pH 0.3). Uniform, multi‐faceted CoP nanoparticles were synthesized by reacting Co nanoparticles with trioctylphosphine. Electrodes comprised of CoP nanoparticles on a Ti support (2 mg cm?2 mass loading) produced a cathodic current density of 20 mA cm?2 at an overpotential of ?85 mV. The CoP/Ti electrodes were stable over 24 h of sustained hydrogen production in 0.50 M H2SO4. The activity was essentially unchanged after 400 cyclic voltammetric sweeps, suggesting long‐term viability under operating conditions. CoP is therefore amongst the most active, acid‐stable, earth‐abundant HER electrocatalysts reported to date. 相似文献
87.
A Cost‐Effective 3D Hydrogen Evolution Cathode with High Catalytic Activity: FeP Nanowire Array as the Active Phase 下载免费PDF全文
Dr. Ping Jiang Qian Liu Yanhui Liang Dr. Jingqi Tian Prof. Abdullah M. Asiri Prof. Xuping Sun 《Angewandte Chemie (International ed. in English)》2014,53(47):12855-12859
Iron is the cheapest and one of the most abundant transition metals. Natural [FeFe]‐hydrogenases exhibit remarkably high activity in hydrogen evolution, but they suffer from high oxygen sensitivity and difficulty in scale‐up. Herein, an FeP nanowire array was developed on Ti plate (FeP NA/Ti) from its β‐FeOOH NA/Ti precursor through a low‐temperature phosphidation reaction. When applied as self‐supported 3D hydrogen evolution cathode, the FeP NA/Ti electrode shows exceptionally high catalytic activity and good durability, and it only requires overpotentials of 55 and 127 mV to afford current densities of 10 and 100 mA cm2, respectively. The excellent electrocatalytic performance is promising for applications as non‐noble‐metal HER catalyst with a high performance–price ratio in electrochemical water splitting for large‐scale hydrogen fuel production. 相似文献
88.
Photocatalytic Water Oxidation by a Pyrochlore Oxide upon Irradiation with Visible Light: Rhodium Substitution Into Yttrium Titanate 下载免费PDF全文
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
89.
Nanocomposites of Tantalum‐Based Pyrochlore and Indium Hydroxide Showing High and Stable Photocatalytic Activities for Overall Water Splitting and Carbon Dioxide Reduction 下载免费PDF全文
Meng‐Chun Hsieh Guan‐Chang Wu Dr. Wei‐Guang Liu Prof. William A. Goddard III Prof. Dr. Chia‐Min Yang 《Angewandte Chemie (International ed. in English)》2014,53(51):14216-14220
Nanocomposites of tantalum‐based pyrochlore nanoparticles and indium hydroxide were prepared by a hydrothermal process for UV‐driven photocatalytic reactions including overall water splitting, hydrogen production from photoreforming of methanol, and CO2 reduction with water to produce CO. The best catalyst was more than 20 times more active than sodium tantalate in overall water splitting and 3 times more active than Degussa P25 TiO2 in CO2 reduction. Moreover, the catalyst was very stable while generating stoichiometric products of H2 (or CO) and O2 throughout long‐term photocatalytic reactions. After the removal of In(OH)3, the pyrochlore nanoparticles remained highly active for H2 production from pure water and aqueous methanol solution. Both experimental studies and density functional theory calculations suggest that the pyrochlore nanoparticles catalyzed the water reduction to produce H2, whereas In(OH)3 was the major active component for water oxidation to produce O2. 相似文献
90.