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Noble metal

Xin-Bao Han, Xing-Yan Tang, Yue Lin, Eduardo Gracia-Espino, Sang-Gui Liu, Hai-Wei Liang, Guang-Zhi Hu, Xin-Jing Zhao, Hong-Gang Liao, Yuan-Zhi Tan, Thomas Wagberg, Su-Yuan Xie, Lan-Sun Zheng
The oxygen evolution reaction is a crucial step in water electrolysis to develop clean and renewable energy. Although noble metal-based catalysts have demonstrated high activity for oxygen evolution reaction, their application have been limited by their high costs and low availability. Here we report the use of a molecule-to-cluster strategy to prepare ultra-small trimetallic clusters by using polyoxometalate molecule as precursors. The ultrafine (0.8 nm) transition metal clusters with controllable chemical composition are obtained...
December 12, 2018: Journal of the American Chemical Society
Minghan Cai, Dongdong Zhang, Lian Duan
Recently, organic light-emitting diodes (OLEDs) employing thermally activated delayed fluorescence (TADF) materials have aroused huge attention in both academia and industry. Compared with fluorescent and phosphorescent materials, TADF materials can theoretically capture 100 % excitons without incorporating noble metals, making them effective emitters and hosts for OLEDs simultaneously. Here, in this review, our recent works on mechanisms and materials of high performance TADF-sensitized phosphorescent (TSP) OLEDs, TADF-sensitized fluorescent (TSF) OLEDs and TADF-sensitized TADF (TST) OLEDs are summarized...
December 10, 2018: Chemical Record: An Official Publication of the Chemical Society of Japan ... [et Al.]
Guihua Liu, Jingde Li, Jing Fu, Gaopeng Jiang, Gregory Lui, Dan Luo, Ya-Ping Deng, Jing Zhang, Zachary P Cano, Aiping Yu, Dong Su, Zhengyu Bai, Lin Yang, Zhongwei Chen
The highly oxidative operating conditions of rechargeable zinc-air batteries causes significant carbon-support corrosion of bifunctional oxygen electrocatalysts. Here, a new strategy for the catalyst support design focusing on oxygen vacancy (OV)-rich, low-bandgap semiconductor is proposed. The OVs promote the electrical conductivity of the oxide support, and at the same time offer a strong metal-support interaction (SMSI), which enables the catalysts to have small metal size, high catalytic activity, and high stability...
December 9, 2018: Advanced Materials
Brigita Vigante, Karolis Leitonas, Dmytro Volyniuk, Viktorija Andruleviciene, Jurate Simokaitiene, Anna Ivanova, Audrius Bucinskas, Juozas Vidas Grazulevicius, Pavel Arsenyan
Aiming to develop all-organic bipolar semiconductors with high charge mobility and efficient E-type fluorescence (so-called TADF) as environmentally-friendly light-emitting materials for optoelectronic applications, four noble metals-free dyes with linear and V-shapes were designed using accepting pyridine-3,5-dicarbonitrile and donating carbazole units. Exploiting donor-acceptor design strategy and using moieties with different donating and accepting abilities, TADF emitters with wide variety of molecular weights were synthesized for getting optimum combination of charge-transporting and fluorescent properties in one TADF molecule...
December 10, 2018: Chemistry: a European Journal
Zhishun Wei, Marcin Janczarek, Maya Endo, Kunlei Wang, Armandas Balčytis, Akio Nitta, Maria G Méndez-Medrano, Christophe Colbeau-Justin, Saulius Juodkazis, Bunsho Ohtani, Ewa Kowalska
Octahedral anatase particles (OAP, with eight equivalent {101} facets) and decahedral anatase particles (DAP, with two additional {001} facets) were modified with nanoparticles of noble metals (Au, Ag, Cu). The titania morphology, expressed by the presence of different arrangements of exposed crystal facets, played a key role in the photocatalytic properties of metal-modified faceted titania. In the UV/vis systems, two-faceted configuration of DAP was more favorable for the reaction efficiency than single-faceted OAP because of an efficient charge separation described by the transfer of electrons to {101} facets and holes to {001} facets...
December 5, 2018: Applied Catalysis. B, Environmental
Junwei Wang, Chrameh Fru Mbah, Thomas Przybilla, Benjamin Apeleo Zubiri, Erdmann Spiecker, Michael Engel, Nicolas Vogel
Clusters in systems as diverse as metal atoms, virus proteins, noble gases, and nucleons have properties that depend sensitively on the number of constituent particles. Certain numbers are termed 'magic' because they grant the system with closed shells and exceptional stability. To this point, magic number clusters have been exclusively found with attractive interactions as present between atoms. Here we show that magic number clusters exist in a confined soft matter system with negligible interactions. Colloidal particles in an emulsion droplet spontaneously organize into a series of clusters with precisely defined shell structures...
December 10, 2018: Nature Communications
Konglin Wu, Zheng Chen, Weng-Chon Cheong, Shoujie Liu, Wei Zhu, Xing Cao, Kaian Sun, Yan Lin, Lirong Zheng, Wensheng Yan, Yuan Pan, Dingsheng Wang, Qing Peng, Chen Chen, Yadong Li
It is of great significance to explore novel synthesis strategies for constructing highly active and low-cost non-noble metal electrocatalysts for water splitting. Herein, we design a novel and efficient coordination-polymerization-pyrolysis (CPP) strategy for preparing cobalt phosphide nanoparticles encapsulated in N-doped porous carbon spheres (CoP@NPCSs) hybrids as a robust bifunctional electrocatalyst for overall water splitting. It can be found that both the carbonization temperature and the molar ratio of metal precursors and dopamine affect the electrocatalytic performance...
December 10, 2018: ACS Applied Materials & Interfaces
Minghan Cai, Dongdong Zhang, Jingyi Xu, Xiangchen Hong, Chongguang Zhao, Xiaozeng Song, Yong Qiu, Hironori Kaji, Lian Duan
Recent researches on noble-metal-free thermally activated delayed fluorescent (TADF) materials have boosted the efficiencies of organic light-emitting diodes (OLEDs) to unity. However, short lifespan still hinders their further practical application. Carrier recombination pathways have been reported to have significant influence on efficiencies of TADF devices, though their effects on device lifetimes remain rarely studied. Here, we have designed and synthesized five pyrimidine or pyrazine/carbazole isomers as hosts for TADF OLEDs to explore the inherent role of Langevin recombination (LR) and trap assisted recombination (TAR) on device lifetimes...
December 10, 2018: ACS Applied Materials & Interfaces
Nengneng Xu, Qi Nie, Lingyiqian Luo, Chen-Zhong Yao, Qiaojuan Gong, Yuyu Liu, Xiaodong Zhou, Jinli Qiao
The exploitation of a high-activity and low-cost bifunctional catalyst for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) as cathode catalyst is a research priority in metal-air batteries (MeABs). Herein, a novel bifunctional hybrid catalyst of hortensia-like MnO2 synergized with carbon nanotubes (CNTs) (MnO2/CNTs) is controllably synthesized by reasonably designing the crystal structure and morphology as well as electronic arrangement. Based on these strategies, the hybrid accelerates the reaction kinetics and avoids the change of structure...
December 7, 2018: ACS Applied Materials & Interfaces
Oriol Piqué, Iskra Z Koleva, Francesc Viñes, Hristiyan A Aleksandrov, Georgi N Vayssilov, Francesc Illas
Carbon Cn moieties on late transition metals are historically regarded as poisoning agents for their use in heterogeneous catalysis. Recent experimental studies combining ab initio simulations showed the promoting catalytic role of subsurface C atoms in Pd surfaces, plus their existence was well established in Ni and Pt surfaces. Here we show, adjoining energetic and kinetic evidences obtained by accurate density functional simulations on surface and nanoparticle models, that such subsurface C species are a general issue to be considered even in coinage noble metal systems...
December 7, 2018: Angewandte Chemie
Jianing Guo, Tingting Li, Qiuli Wang, Ningyuan Zhang, Yuanhui Cheng, Zhonghua Xiang
Covalent organic polymers (COPs) as emerging porous materials with ultrahigh hydrothermal stability and well-defined and adjustable architectures have aroused great interest in the electrochemical field. Here, we reported a rational design approach for the preparation of a bifunctional electrocatalyst with the assistance of a predesigned bimetallic covalent organic polymer. With the predesigned nitrogen position and structural features of COP materials, the obtained CCOPTDP-FeNi-SiO2 catalyst affords a remarkable bifunctional performance with a positive half-wave potential (0...
December 7, 2018: Nanoscale
Yazhou Huang, Lei Liu, Xiaolin Liu
Electrochemical water splitting into H2 and O2 has attracted wide attentions owing to the urgent need for clean and renewable energy sources. However, the scarcity and high-cost limit the large-scale application of noble metal catalysts such as IrO2 and RuO2. In this work, as a low-cost catalyst for the electrochemical O2 evolution reaction (OER), MoS2 nanoflakes were obtained by atomic layer deposition (ALD) using MoCl5 and H2S on carbon fiber paper (CFP) surface. According to the results of electrochemical measurements, the MoS2 nanoflakes exhibit an excellent catalytic activity, and the activity can be modulated by controlling the density and the internal resistance of MoS2 nanoflakes...
November 7, 2018: Nanotechnology
Kumaranchira Ramankutty Krishnadas, Ganapati Natarajan, Ananya Baksi, Atanu Ghosh, Esma Khatun, Thalappil Pradeep
We discuss the role of the metal-ligand (M-L) interfaces in the chemistry of ligand protected, atomically precise noble metal clusters, a new and expanding family of nanosystems, in solution as well as in gas phase. A few possible mechanisms in which the structure and dynamics of M-L interfaces could trigger intercluster exchange reactions are presented first. How interparticle chemistry can be a potential mechanism of Ostwald ripening, a well-known particle coarsening process, is also discussed. Reaction of Ag59(2,5-DCBT)32 (DCBT = dichlorobenzenethiol) with 2,4-DCBT leading to the formation of Ag44(2,4-DCBT)30 is presented, demonstrating the influence of the ligand structure in ligand-induced chemical transformations of clusters...
December 6, 2018: Langmuir: the ACS Journal of Surfaces and Colloids
Dario Formenti, Francesco Ferretti, Florian Korbinian Scharnagl, Matthias Beller
The reduction of nitro compounds to the corresponding amines is one of the most utilized catalytic processes in the fine and bulk chemical industry. The latest development of catalysts with cheap metals like Fe, Co, Ni, and Cu has led to their tremendous achievements over the last years prompting their greater application as "standard" catalysts. In this review, we will comprehensively discuss the use of homogeneous and heterogeneous catalysts based on non-noble 3d-metals for the reduction of nitro compounds using various reductants...
December 5, 2018: Chemical Reviews
Un Jeong Kim, Jun Suk Kim, Noejung Park, Sanghyub Lee, Ukjae Lee, Yeonsang Park, Jinbong Seok, Sungwoo Hwang, Hyungbin Son, Young Hee Lee
Metal/graphene interface has been one of the most important research topics with regard to charge screening, charge transfer, contact resistance, and solar cells. Chemical bond formation of metal/graphene can be deduced from the defect induced D-band and its second-order mode, 2D band, measured by Raman spectroscopy, as a simple and non-destructive method. However, a phonon mode located at ~ 1350 cm-1 , which is normally known as the defect-induced D-band, is intriguing for graphene deposited with noble metals (Ag, Au, and Cu)...
December 5, 2018: ACS Nano
Yuanyuan Guo, Zhengfei Dai, Jun Lu, Xiaoqiao Zeng, Yifei Yuan, Xuanxuan Bi, Lu Ma, Tianpin Wu, Qingyu Yan, Khalil Amine
Low-cost and highly active electrocatalysts are attractive for Li-O2 applications. Herein, a 3D interconnected plate architecture consisting of ultra-small Co-Ni grains embedded in lithium hydroxide nanoplates (Co2Ni@LiOH) is designed and prepared by a lithiation strategy at room temperature. This catalyst exhibits a remarkably reduced charge potential of ~ 3.4 V at 50 µA cm-2, which leads to the high roundtrip efficiency of ~ 79%, among the best levels reported and a cycle life of up to 40 cycles. The well-aligned network facilitates the oxygen diffusion and the electrolyte penetration into the electrode...
December 4, 2018: ACS Applied Materials & Interfaces
Xiaohui Xu, Tugba Isik, Subhajit Kundu, Volkan Ortalan
Noble metallic nanoparticles with unique plasmonic properties are useful in a variety of applications including bio-imaging, sensing, cancer therapy, etc. The properties of metallic nanoparticles can be tuned in multiple ways, among which laser welding is a highly efficient method. In this study, laser-induced inter-welding of Ag-Au nanoparticle (NP) dimers was investigated using in situ transmission electron microscopy (TEM) and energy-dispersive X-ray spectroscopy (EDX). For the first time, the welding process was directly visualized...
December 4, 2018: Nanoscale
Yuxiao Zhang, Yasutaka Kuwahara, Kohsuke Mori, Hiromi Yamashita
Molybdenum disulfide (MoS₂) has been regarded as a favorable photocatalytic co-catalyst and efficient hydrogen evolution reaction (HER) electrocatalyst alternative to expensive noble-metals catalysts, owing to earth-abundance, proper bandgap, high surface area, and fast electron transfer ability. In order to achieve a higher catalytic efficiency, defects strategies such as phase engineering and vacancy introduction are considered as promising methods for natural 2H-MoS₂ to increase its active sites and promote electron transfer rate...
December 2, 2018: Chemistry, An Asian Journal
Tomokazu Kiyonaga, Akira Heima
The discovery of the excellent thermal catalytic activity of Au nanoparticles (NPs) for CO oxidation (Haruta et al., 1987 [1]) triggered intensive research on thermal and visible photo-catalysis based on these NPs (Ref. [2]). Recently, catalysts containing two types of metal NPs loaded onto a TiO2 support, i.e., NPs consisting of a separate Au photocatalyst (average size: 13 nm) and another noble metal, were developed as highly efficient visible photocatalysts for several important chemical reactions (Tanaka et al...
2018: MethodsX
Aasif Hassan Sheikh, Moumita Bose, Sabyasachi Sarkar, Ameerunisha Begum
With large surface area and versatile electronic behaviour, the composites of Fe₄S₄(SRS)₄ nanoclusters and functionalized carbon nanotubes (f-CNTs), are expected to catalyze the conversion of protons to hydrogen gas at lower electro-potentials with higher output than a platinum electrode. In search of a non-noble metal based catalytic material, we report for the first time, the isolation of unimolecular iron-sulfur cubane cluster, [Fe₄( μ -S)₄(mnt)₄], ( 1 ) (mnt = maleonitriledithiolate) as nanocubes (63×85×120 nm) in MeCN-EtOH (MeCN is acetonitrile, while EtOH is ethanol) solvents and bimolecular [NBu₄]₄[Fe₄( μ -S)₄(mnt)₄] as nanocuboctahedra (120×121×125 nm) in pure EtOH...
May 1, 2019: Journal of Nanoscience and Nanotechnology
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