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2D catalyst

Chenbao Lu, Diana Tranca, Jian Zhang, Fermı N Rodrı Guez Hernández, Yuezeng Su, Xiaodong Zhuang, Fan Zhang, Gotthard Seifert, Xinliang Feng
Molybdenum carbide (Mo2C) based catalysts were found to be one of the most promising electrocatalysts for hydrogen evolution reaction (HER) in acid media in comparison with Pt-based catalysts but were seldom investigated in alkaline media, probably due to the limited active sites, poor conductivity, and high energy barrier for water dissociation. In this work, Mo2C-embedded nitrogen-doped porous carbon nanosheets (Mo2C@2D-NPCs) were successfully achieved with the help of a convenient interfacial strategy. As a HER electrocatalyst in alkaline solution, Mo2C@2D-NPC exhibited an extremely low onset potential of ∼0 mV and a current density of 10 mA cm(-2) at an overpotential of ∼45 mV, which is much lower than the values of most reported HER electrocatalysts and comparable to the noble metal catalyst Pt...
March 20, 2017: ACS Nano
Kenji D Okochi, Luca Monfregola, Sarah Michelle Dickerson, Ryan McCaffrey, Dylan W Domaille, Chao Yu, Glenn R Hafenstine, Yinghua Jin, Jennifer N Cha, Robert D Kuchta, Marvin Caruthers, Wei Zhang
Small molecule/DNA hybrids (SMDHs) have been considered as nanoscale building blocks for engineering 2D and 3D supramolecular DNA assembly. Herein, we report an efficient on-bead amide-coupling approach to prepare SMDHs with multiple oligodeoxynucleotide (ODN) strands. Our method is high yielding under mild and user-friendly conditions with various organic substrates and homo- or mixed-sequenced ODNs. Metal catalysts and moisture- and air-free conditions are not required. The products can be easily analyzed by LC-MS with accurate mass resolution...
March 20, 2017: Journal of Organic Chemistry
K Pramoda, U Gupta, M Chhetri, A Bandyopadhyay, S K Pati, C N R Rao
Generation of hydrogen by photochemical, electrochemical, and other means is a vital area of research today, and a variety of materials have been explored as catalysts for this purpose. C3N4, MoS2, and nitrogenated RGO (NRGO) are some of the important catalytic materials investigated for the hydrogen evolution reaction (HER) reaction, but the observed catalytic activities are somewhat marginal. Prompted by preliminary reports that covalent cross-linking of 2D materials to generate heteroassemblies or nanocomposites may have beneficial effect on the catalytic activity, we have synthesized nanocomposites wherein C3N4 is covalently bonded to MoS2 or NRGO nanosheets...
March 20, 2017: ACS Applied Materials & Interfaces
Riteshkumar Vishwakarma, Mohamad Saufi Rosmi, Kazunari Takahashi, Yuji Wakamatsu, Yazid Yaakob, Mona Ibrahim Araby, Golap Kalita, Masashi Kitazawa, Masaki Tanemura
Low-temperature growth, as well as the transfer free growth on substrates, is the major concern of graphene research for its practical applications. Here we propose a simple method to achieve the transfer free graphene growth on SiO2 covered Si (SiO2/Si) substrate at 250 °C based on a solid-liquid-solid reaction. The key to this approach is the catalyst metal, which is not popular for graphene growth by chemical vapor deposition. A catalyst metal film of 500 nm thick was deposited onto an amorphous C (50 nm thick) coated SiO2/Si substrate...
March 2, 2017: Scientific Reports
Pieter Tack, Bart Vekemans, Brecht Laforce, Jennifer Rudloff-Grund, Willinton Y Hernández, Jan Garrevoet, Gerald Falkenberg, Frank Brenker, Pascal Van Der Voort, Laszlo Vincze
Using X-ray absorption near edge structure (XANES) spectroscopy, information on the local chemical structure and oxidation state of an element of interest can be acquired. Conventionally, this information can be obtained in a spatially resolved manner by scanning a sample through a focused X-ray beam. Recently, full-field methods have been developed to obtain direct 2D chemical state information by imaging a large sample area. These methods are usually in transmission mode, thus restricting the use to thin and transmitting samples...
February 7, 2017: Analytical Chemistry
Shu-Wei Liu, Hua-Ping Wang, Qiang Xu, Tian-Bao Ma, Gui Yu, Chenhui Zhang, Dechao Geng, Zhiwei Yu, Shengguang Zhang, Wenzhong Wang, Yuan-Zhong Hu, Hui Wang, Jianbin Luo
Superlubricity of graphite and graphene has aroused increasing interest in recent years. Yet how to obtain a long-lasting superlubricity between graphene layers, under high applied normal load in ambient atmosphere still remains a challenge but is highly desirable. Here, we report a direct measurement of sliding friction between graphene and graphene, and graphene and hexagonal boron nitride (h-BN) under high contact pressures by employing graphene-coated microsphere (GMS) probe prepared by metal-catalyst-free chemical vapour deposition...
February 14, 2017: Nature Communications
Qingyong Tian, Wei Wu, Jun Liu, Zhaohui Wu, Weijing Yao, Jin Ding, Changzhong Jiang
The development of photocatalysts with superior photoactivity and stability for the degradation of organic dyes is very important for environmental remediation. In this study, we have presented a multidimensional (1D and 2D) structured CdS/ZnIn2S4/RGO photocatalyst with superior photocatalytic performance. The CdS/ZnIn2S4 helical dimensional heterostructures (DHS) were prepared via a facile solvothermal synthesis method to facilitate the epitaxial growth of 2D ZnIn2S4 nanosheets on 1D CdS nanowires. Ultrathin 2D ZnIn2S4 nanosheets have grown uniformly and perpendicular to the surface of 1D CdS nanowires...
February 7, 2017: Dalton Transactions: An International Journal of Inorganic Chemistry
Piotr Paluch, Natalia Potrzebowska, Agnieszka M Ruppert, Marek J Potrzebowski
In this work for the first time we show the power of solid state NMR spectroscopy in structural analysis of alumina and catalysts supported on the alumina surface employing very fast (60kHz) magic angle spinning (MAS) technique. In the methodological part we demonstrate that under such MAS condition, cross-polarization (CP) from proton to aluminum is an efficient process when a very weak (27)Al RF field is applied. The mechanism of CP transfer and the Hartmann-Hahn (H-H) matching conditions were tested for (27)Al RF fields equal to 3...
January 26, 2017: Solid State Nuclear Magnetic Resonance
Heather Vanselous, Ashley M Stingel, Poul B Petersen
Molecular monolayers exhibit structural and dynamical properties that are different from their bulk counterparts due to their interaction with the substrate. Extracting these distinct properties is crucial for a better understanding of processes such as heterogeneous catalysis and interfacial charge transfer. Ultrafast nonlinear spectroscopic techniques such as 2D infrared (2D IR) spectroscopy are powerful tools for understanding molecular dynamics in complex bulk systems. Here, we build on technical advancements in 2D IR and heterodyne-detected sum frequency generation (SFG) spectroscopy to study a CO2 reduction catalyst on nanostructured TiO2 with interferometric 2D SFG spectroscopy...
February 6, 2017: Journal of Physical Chemistry Letters
Yanyan Chen, Jun Hu, Honglin Diao, Wenjing Luo, Yu-Fei Song
The efficient catalytic oxidation of water to dioxygen plays a significant role in solar fuel and artificial photosynthetic systems. It remains highly challenging to develop oxygen evolution reaction (OER) catalysts with high activity and low cost under mild conditions. Here, a new composite material is reported based on ultrathin 2D Co3 O4 nanosheets and reduced graphene oxides (rGO) by means of a one-pot hydrothermal strategy. The ultrathin Co3 O4 /rGO nanocomposite shows superior stability under alkaline conditions and exhibits an overpotential of 290 mV with a Tafel slope of 68 mA dec(-1) , which is much smaller than that of bare Co3 O4 catalyst...
February 2, 2017: Chemistry: a European Journal
Qiang Wu, Lijun Yang, Xizhang Wang, Zheng Hu
Carbon-based nanomaterials have been the focus of research interests in the past 30 years due to their abundant microstructures and morphologies, excellent properties, and wide potential applications, as landmarked by 0D fullerene, 1D nanotubes, and 2D graphene. With the availability of high specific surface area (SSA), well-balanced pore distribution, high conductivity, and tunable wettability, carbon-based nanomaterials are highly expected as advanced materials for energy conversion and storage to meet the increasing demands for clean and renewable energies...
February 1, 2017: Accounts of Chemical Research
Chong Lin, Guanghao Wu, Huiqin Li, Yanmin Geng, Gang Xie, Jianhui Yang, Bin Liu, Jian Jin
We reported a facile and scalable salt-templated approach to produce monodisperse Rh nanoparticles (NPs) on ultrathin carbon nanosheets with the assistance of calcination under inert gas. More importantly, in spite of the essentially poor ORR activity of Rh/C, the acquired Rh/C hybrid nanosheets display a comparable ORR activity to the optimal commercial Pt/C catalyst, which may be due to the extra-small size of Rh NPs and the 2D defect-rich amorphous carbon nanosheets that can facilitate the charge transfer and reactive surface exposure...
January 24, 2017: Nanoscale
Utz Obenaus, Gerhard Althoff-Ospelt, Swen Lang, Robin Himmelmann, Michael Hunger
The present work introduces a novel method for the selective detection of (1) H NMR anti-phase signals caused by the pairwise incorporation of parahydrogen into olefins on noble-metal-containing catalysts. Via a two-dimensional (2D) nutation NMR experiment, the anti-phase signals of hyperpolarized (1) H nuclei are separated due to their double nutation frequency compared to that of thermally polarized (1) H nuclei. For demonstrating this approach, parahydrogen induced polarization (PHIP) was achieved via the hydrogenation of propene with parahydrogen on platinum-containing silica and investigated by in situ (1) H MAS NMR spectroscopy under continuous-flow conditions, that is, the hydrogenation reaction was performed inside the magnet of the NMR spectrometer...
January 23, 2017: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
Aozhen Xie, Ningning Xuan, Kun Ba, Zhengzong Sun
Graphene, the sp(2) carbonaceous two-dimensional (2D) material, is gaining more attention in recent electrochemical studies. However, this atomic thick electrode usually suffers with surface contamination and poor electrochemical endurance. To overcome the drawbacks, we developed a PMMA-assisted, flipped transfer method to fabricate the graphene electrode with pristine surface and prolonged lifetime in hydrogen evolution reaction (HER). The HER performances of the single-layer graphene (SLG) were evaluated on various insulating and conductive substrates, including SiO2, polymers, SLG, highly oriented pyrolytic graphite (HOPG), and copper...
January 24, 2017: ACS Applied Materials & Interfaces
Jianbang Wang, Jie Chao, Huajie Liu, Shao Su, Lianhui Wang, Wei Huang, Itamar Willner, Chunhai Fan
DNA hydrogels hold great potential for biological and biomedical applications owing to their programmable nature and macroscopic sizes. However, most previous studies involve spontaneous and homogenous gelation procedures in solution, which often lack precise control. A clamped hybridization chain reaction (C-HCR)-based strategy has been developed to guide DNA self-assembly to form macroscopic hydrogels. Analogous to catalysts in chemical synthesis or seeds in crystal growth, we introduced DNA initiators to induce the gelation process, including crosslinked self-assembly and clamped hybridization in three dimensions with spatial and temporal control...
January 12, 2017: Angewandte Chemie
Yikai Xu, Magdalena P Konrad, Johann L Trotter, Colin P McCoy, Steven E J Bell
2D arrays of metal nanoparticles formed at liquid-liquid interfaces have been fixed in situ to a thin polymer support to create freestanding large (cm(2) ) composite films where the particles remain exposed rather than being trapped within the polymer. Applications of these flexible robust 2D nanoparticle arrays as sensors, thin film conductors, antimicrobial coatings, and dip-in catalysts are shown.
January 2017: Small
Avijit Kumar, Kaustuv Banerjee, Peter Liljeroth
Molecular self-assembly is a well-known technique to create highly functional nanostructures on surfaces. Self-assembly on two-dimensional (2D) materials is a developing field driven by the interest in functionalization of 2D materials in order to tune their electronic properties. This has resulted in the discovery of several rich and interesting phenomena. Here, we review this progress with an emphasis on the electronic properties of the adsorbates and the substrate in well-defined systems, as unveiled by scanning tunneling microscopy...
January 3, 2017: Nanotechnology
Longtao Han, Predrag Krstić
We find a possible channel for direct nanosynthesis of boron-nitride (BN) nanostructures, including growth of BN nanotubes from a mixture of BN diatomic molecules by quantum-classical molecular dynamics simulations. No catalyst or boron nanoparticle is needed for this synthesis, however the conditions for the synthesis of each of the nanostructures, such as temperature and flux of the BN feedstock are identified and are compatible with the conditions in an electric arc at high pressure. We also find that BN nanostructures can be synthetized by feeding a boron nanoparticle by BN diatomic molecules, however if hydrogen rich molecules like NH3 or HBNH are used as a feedstock, two-dimensional nanoflake stable structures are formed...
January 3, 2017: Nanotechnology
Peter A Eckert, Kevin J Kubarych
Hydrogenase enzymes enable organisms to use H2 as an energy source, having evolved extremely efficient biological catalysts for the reversible oxidation of molecular hydrogen. Small-molecule mimics of these enzymes provide both simplified models of the catalysis reactions and potential artificial catalysts that might be used to facilitate a hydrogen economy. We have studied two diiron hydrogenase mimics, μ-pdt-[Fe(CO)3]2 and μ-edt-[Fe(CO)3]2 (pdt = propanedithiolate, edt = ethanedithiolate), in a series of alkane solvents and have observed significant ultrafast spectral dynamics using two-dimensional infrared (2D-IR) spectroscopy...
January 12, 2017: Journal of Physical Chemistry. A
Miguel Ayán-Varela, Óscar Pérez-Vidal, Juan I Paredes, José M Munuera, Silvia Villar-Rodil, María Díaz-González, César Fernández-Sánchez, Virgilia S Silva, Mónica Cicuéndez, Mercedes Vila, Amelia Martínez-Alonso, Juan M D Tascón
The exfoliation and colloidal stabilization of layered transition metal dichalcogenides (TMDs) in an aqueous medium using functional biomolecules as dispersing agents have a number of potential benefits toward the production and practical use of the corresponding two-dimensional materials, but such a strategy has so far remained underexplored. Here, we report that DNA and RNA nucleotides are highly efficient dispersants in the preparation of stable aqueous suspensions of MoS2 and other TMD nanosheets at significant concentrations (up to 5-10 mg mL(-1))...
January 11, 2017: ACS Applied Materials & Interfaces
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