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water splitting

John T Kelly, Martin Mayer, Adam C Kennedy, Christian Schemel, Knut R Asmis
We investigate the perchlorate anion, ClO4 - , microhydrated with up to eight water molecules using infrared photodissociation (IRPD) spectroscopy aided by density functional theory computations. The features observed in the IRPD spectra of D2 -tagged ClO4 - (H2 O)n with n = 0-8 in the O-H stretching (2800-3800 cm-1 ) and fingerprint (800-1800 cm-1 ) spectral ranges are assigned to vibrational modes of the solvent, i.e., free and hydrogen-bonded O-H stretching and H2 O bending modes, and of the solute, i.e...
June 14, 2018: Journal of Chemical Physics
Jessalyn A DeVine, Ali Abou Taka, Mark C Babin, Marissa L Weichman, Hrant P Hratchian, Daniel M Neumark
Slow electron velocity-map imaging spectroscopy of cryogenically cooled TiO3 H2 - anions is used to probe the simplest titania/water reaction, TiO2 0/- + H2 O. The resultant spectra show vibrationally resolved structure assigned to detachment from the cis-dihydroxide TiO(OH)2 - geometry based on density functional theory calculations, demonstrating that for the reaction of the anionic TiO2 - monomer with a single water molecule, the dissociative adduct (where the water is split) is energetically preferred over a molecularly adsorbed geometry...
June 14, 2018: Journal of Chemical Physics
Timothy T Duignan, Marcel D Baer, Christopher J Mundy
The tetra-phenyl arsonium and tetra-phenyl borate (TATB) assumption is a commonly used extra-thermodynamic assumption that allows single ion free energies to be split into cationic and anionic contributions. The assumption is that the values for the TATB salt can be divided equally. This is justified by arguing that these large hydrophobic ions will cause a symmetric response in water. Experimental and classical simulation work has raised potential flaws with this assumption, indicating that hydrogen bonding with the phenyl ring may favor the solvation of the TB- anion...
June 14, 2018: Journal of Chemical Physics
Jian Zhang, Xianxian Li, Yiteng Liu, Zhaowei Zeng, Xu Cheng, Yadong Wang, Wenmao Tu, Mu Pan
Rational design and understanding of the intrinsic mechanism are critical to develop highly active and durable electrocatalysts. In this study, a series of bi-metallic boride catalysts based on Ni and Co were prepared, and their activities were evaluated. The synthesised Co-10Ni-B catalyst exhibited excellent activity for water splitting in a 1 M KOH electrolyte. The overpotential was 330 mV at a current density of 10 mA cm-2, better than previously reported mono-metallic borides and even IrO2. The synergistic effect of Co and Ni was proved by X-ray photoelectron spectroscopy and electrochemical impedance spectroscopy...
June 15, 2018: Nanoscale
Shihab Uddin, Markus Löw, Shahnaj Parvin, Glenn J Fitzgerald, Sabine Tausz-Posch, Roger Armstrong, Garry O'Leary, Michael Tausz
Through stimulation of root growth, increasing atmospheric CO2 concentration ([CO2]) may facilitate access of crops to sub-soil water, which could potentially prolong physiological activity in dryland environments, particularly because crops are more water use efficient under elevated [CO2] (e[CO2]). This study investigated the effect of drought in shallow soil versus sub-soil on agronomic and physiological responses of wheat to e[CO2] in a glasshouse experiment. Wheat (Triticum aestivum L. cv. Yitpi) was grown in split-columns with the top (0-30 cm) and bottom (31-60 cm; 'sub-soil') soil layer hydraulically separated by a wax-coated, root-penetrable layer under ambient [CO2] (a[CO2], ∼400 μmol mol-1) or e[CO2] (∼700 μmol mol-1) [CO2]...
2018: PloS One
Sen Xue, Long Chen, Zhibo Liu, Hui-Ming Cheng, Wencai Ren
Developing new electrocatalysts is essentially important for efficient water splitting to produce hydrogen. Two-dimensional (2D) materials provide great potential for high-performance electrocatalysts because of their high specific surface area, abundant active edges, and tunable electronic structure. Here, we report few-layer NiPS3 nanosheet-graphene composites for high-performance electrocatalysts for oxygen evolution reaction (OER). The pure NiPS3 nanosheets show an overpotential of 343 mV for a current density of 10 mA cm-2 , which is comparable to that for IrO2 and RuO2 catalysts...
June 14, 2018: ACS Nano
Yuanxing Fang, Yuntao Xu, Xiaochun Li, Yiwen Ma, Xinchen Wang
Solar-to-fuel conversion via photoelectrochemical (PEC) water splitting has the potential to ease current energy and environmental concerns. In pursuit of sustainability, polymeric carbon nitride (PCN) photosensitizers are receiving increasing attention as replacements for their inorganic counterparts. However, intense charge recombination, primarily because of the numerous surface defects, limits the use of PCN in PEC systems. Herein, photoanodes are designed by coating PCN films onto highly conductive yttrium (Y) doped zinc oxide (ZnO) nanorods (NRs) serving as charge collectors...
June 14, 2018: Angewandte Chemie
Bernard Gottschalk
To find a deterministic pencil beam algorithm that computes, from first principles, the dose in some region of interest when a known heterogeneous terrain is irradiated by known proton beams.
 Methods: The terrain is discretized into slabs perpendicular to the nominal beam direction. Pencil beams (PBs) are transported through each slab using generalized Fermi-Eyges theory with the correct stopping and scattering powers for each material (no water-like assumption).
 At transverse heterogeneities PBs are divided into smaller ones using either redefinition (all PBs divided) or dynamic splitting (PBs divided one at a time as needed)...
June 14, 2018: Physics in Medicine and Biology
Hua Wang, Mei Ming, Min Hu, Caili Xu, Yi Wang, Yun Zhang, Daojiang Gao, Jian Bi, Guangyin Fan, Jin-Song Hu
Developing efficient catalytic materials for electrochemical water splitting is important. Herein, uniformly dispersed and size-controllable iridium (Ir) nanoparticles (NPs) were prepared using a nitrogen-functionalized carbon (Ir/CN) as the support. We found that nitrogen function can simultaneously modulate the size of Ir NPs to substantially enhance the catalytically active sites and adjust the electronic structure of Ir, thereby promoting electrocatalytic activity for water splitting. Consequently, the as-synthesized Ir/CN shows excellent electrocatalytic performance with overpotentials of 12 and 265 mV for hydrogen and oxygen evolution reactions in basic medium, respectively...
June 14, 2018: ACS Applied Materials & Interfaces
Li Shi, Wei Zhou, Zhao Li, Supriya Koul, Akihiro Kushima, Yang Yang
Non-metallic materials with localized surface plasmon resonance (LSPR) have a great potential for solar energy harvesting applications. Exploring new non-metallic plasmonic materials is desirable yet challenging. Herein, a novel non-metallic plasmonic perovskite photoelectrode, namely SrTiO3, with a periodically ordered nanoporous structure showing an intense LSPR in the visible light region is reported. The crystalline-core@amorphous-shell structure of the SrTiO3 photoelectrode enables a strong LSPR due to the high density of free charge carriers introduced by oxygen vacancies in the amorphous shell...
June 13, 2018: ACS Nano
Srabanti Ghosh, Rajendra N Basu
Electrocatalytic oxygen reduction reaction (ORR), oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) have attracted widespread attention because of their important role in the application of various energy storage and conversion devices, such as fuel cells, metal-air batteries and water splitting devices. However, the sluggish kinetics of the HER/OER/ORR and their dependency on expensive noble metal catalysts (e.g., Pt) obstruct their large-scale application. Hence, the development of efficient and robust bifunctional or trifunctional electrocatalysts in nanodimension for both oxygen reduction/evolution and hydrogen evolution reactions is highly desired and challenging for their commercialization in renewable energy technologies...
June 13, 2018: Nanoscale
Jianglong Mu, Hui Miao, Enzhou Liu, Juan Feng, Feng Teng, Dekai Zhang, Yumeng Kou, Yanping Jin, Jun Fan, Xiaoyun Hu
Excellent PEC efficiency, good reusability and the super stability of trap-like SnS2/TiO2 nanotube arrays (NTs)-based photoanodes are reported. Specifically, the SnS2/TiO2-180 °C (ST-180) photoanode exhibited the highest photocurrent density (1.05 mA cm-2) and an optimal η (0.73%) at 0.5 V (vs. SCE) under simulated light irradiation (AM 1.5G), which are 4.6 and 3.8 times higher than those of pure TiO2 NTs (0.23 mA cm-2 and 0.19%). The IPCE values of ST-180 can reach 21.5% (365 nm) and 13.8% (420 nm), which are much higher than those of pure TiO2 NTs (10...
June 13, 2018: Nanoscale
Husna Siddiqui, Khan Bilal Mukhtar Ahmed, Shamsul Hayat
BRs are polyhydroxylated sterol derivatives, classified as phytohormones. Plants of Brassica juncea var. Varuna were grown in pots and an aqueous solution (10-8  M) of two brassinosteroid isomers 28-homobrassinolide (HBL) and 24-epibrassinolide (EBL) of same concentration (10-8  M) was applied to their leaves. The treatment up-regulated the photosynthetic machinery directly by enhancing water splitting activity, photochemical quenching, non-photochemical quenching, maximum PSII efficiency, actual PSII efficiency, electron transport rate, stomatal movement, stomatal conductance, internal CO2 concentration, transpiration rate, net photosynthetic rate and carbohydrate synthesis...
May 29, 2018: Plant Physiology and Biochemistry: PPB
Zhe Xu, Wenchao Li, Yadong Yan, Hongxu Wang, Heng Zhu, Meiming Zhao, Shicheng Yan, Zhigang Zou
Sluggish water dissociation kinetics on non-precious metal electrocatalysts limit the development of economical hydrogen production from water-alkali electrolysers. Here, using Co3N electrocatalyst as a prototype, we find that during water splitting in alkaline electrolyte a cobalt-containing hydroxide formed on the surface of Co3N, which greatly decrease the activation energy of water dissociation (Volmer step, a main rate-determining step for water splitting in alkaline electrolyte). Combining the cobalt ion poisoning test and theoretical calculations, the efficient hydrogen production on Co3N electrocatalyst would benefit from the favorable water dissociation on in-situ formed cobalt-containing hydroxide and low hydrogen production barrier on the nitrogen sites of Co3N...
June 11, 2018: ACS Applied Materials & Interfaces
Dong Heon Nam, Jenny Zhang, Virgil Andrei, Nikolay Kornienko, Nina Heidary, Andreas Wagner, Kenichi Nakanishi, Katarzyna Sokol, Barnaby Slater, Ingo Zebger, Stephan Hofmann, Juan Fontecilla-Camps, Chan Beum Park, Erwin Reisner
Hydrogenases (H2ases) are benchmark electrocatalysts in H2 production, both in biology and (photo)catalysis in vitro. We report the tailoring of a p-type Si photocathode for optimal loading and wiring of H2ase by the introduction of a hierarchical inverse opal (IO) TiO2 interlayer. This proton reducing Si|IO-TiO2|H2ase photocathode is capable of driving overall water splitting in combination with a complementary photoanode. We demonstrate unassisted (bias-free) water-splitting by wiring Si|IO-TiO2|H2ase to a modified BiVO4 photoanode in a photoelectrochemical (PEC) cell during several hours of irradiation...
June 11, 2018: Angewandte Chemie
Matthias Driess, Carsten Walter, Prashanth Menezes, Holger Dau, Stefan Loos
The development of inexpensive, earth abundant and bioinspired oxygen evolution (water oxidation) electrocatalysts that are easily accessible and scalable is a principal requirement regarding the feasibility of water splitting for large-scale chemical energy storage. Here we present a unique, versatile and scalable approach to fabricate manganese oxide films starting from single layers to multi-layers, with controlled thickness and high reproducibility. The resulting MnOx films are comprised of small nanostructures that are assembled closely, in form of porous sponge-like layers...
June 11, 2018: ChemSusChem
Jakub Krajniak, Zidan Zhang, Sudharsan Pandiyan, Eric Nies, Giovanni Samaey
We develop novel parallel algorithms that allow molecular dynamics simulations in which byproduct molecules are created and removed because of the chemical reactions during the molecular dynamics simulation. To prevent large increases in the potential energy, we introduce the byproduct molecules smoothly by changing the non-bonded interactions gradually. To simulate complete equilibrium reactions, we allow the byproduct molecules attack and destroy created bonds. Modeling of such reactions are, for instance, important to study the pore formation due to the presence of e...
June 11, 2018: Journal of Computational Chemistry
Wei Shi, Xiuxia Zhao, Jianrui Feng, Jing Liu, Guangming Yang, Guichang Wang, Peng Cheng
Photocatalytic water splitting for hydrogen production using sustainable sunlight is a promising alternative to industrial hydrogen production. However, the scarcity of highly active, recyclable, inexpensive photocatalysts impedes the development of photocatalytic hydrogen evolution reaction (HER) schemes. Herein, a metal-organic framework (MOF)-template strategy was developed to prepare non-noble metal cocatalyst/solid solution heterojunction NiS/ZnxCd1-xS with superior photocatalytic HER activity. By adjusting the doping metal concentration in MOFs, the chemical compositions and bandgaps of the heterojunctions can be fine-tuned, and the light absorption capacity and photocatalytic activity were further optimized...
June 10, 2018: Angewandte Chemie
Wenwen Xu, Zhiyi Lu, Xiaoming Sun, Lei Jiang, Xue Duan
Gas-involving electrochemical reactions, including gas evolution reactions and gas consumption reactions, are essential components of the energy conversion processes and gathering elevating attention from researchers. Besides the development of highly active catalysts, gas management during gas-involving electrochemical reactions is equally critical for industrial applications to achieve high reaction rates (hundreds of milliamperes per square centimeter) under practical operation voltages. Biomimetic surfaces, which generally show regular micro/nanostructures, offer new insights to address this issue because of their special wetting capabilities...
June 8, 2018: Accounts of Chemical Research
Xiaohu Luo, Qiulan Zhou, Shuo Du, Ji Li, Jiawen Zhong, Xiulin Deng, Yali Liu
The exploration of highly efficient and stable bifunctional electrocatalysts for the over water splitting is currently of extreme interest for efficient conversion of sustainable energy sources. Herein, we provide an earth-abundant, low-cost, and highly efficient bifunctional electrocatalyst composed of cobalt sulfide (Co9S8) and molybdenum carbide (Mo2C) nanoparticles anchored to metal-organic framworks (MOFs) derived nitrogen, sulfur-co-doped graphitic carbon (Co9S8-NSC@Mo2C). The new composite mode of the electrocatalyst was realized through simple pyrolysis processes...
June 8, 2018: ACS Applied Materials & Interfaces
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