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Noble metal

Lei Wang, Tianjiao Meng, Chunxia Chen, Yanwei Fan, Qianqian Zhang, Huan Wang, Yufan Zhang
The construction of highly active and stable non-noble metal electrocatalysts for oxygen evolution reaction (OER) is a crucial requirement for green energy utilization. Herein, we report a novel hybrid nanostructure of Zn/Co bimetallic oxide (Znx Co3-x O4 ) hollow polyhedron through a pyrolysis-oxidation strategy derived from bimetallic Zn, Co-zeolitic imidazolate frameworks (ZnCo-ZIFs) rhombic polyhedral. Benefiting from the synergistic effects between highly active metal oxide and the unique polyhedron structure, the Znx Co3-x O4 hollow polyhedron hybrid displayed outstanding electrocatalytic performances in alkaline media...
August 12, 2018: Journal of Colloid and Interface Science
Maria A Komkova, Elena E Karyakina, Arkady A Karyakin
We synthesized Prussian Blue (PB) nanoparticles through catalytic reaction involving hydrogen peroxide (H2O2) activation. The resulting nanoparticles display the size-dependent catalytic rate constants in H2O2 reduction, which are significantly improved compared to natural enzyme peroxidase: for PB nanoparticles 200 nm in diameter the turnover number is 300 times higher, for 570 nm diameter nanoparticles - four orders of magnitude higher. Comparing to the known peroxidase-like nanozymes, the advantages of the reported PB nanoparticles are their true enzymatic properties: (i) enzymatic specificity (an absence of oxidase-like activity) and (ii) an ability to operate in physiological solutions...
August 17, 2018: Journal of the American Chemical Society
Wei Quan, Kesheng Shen, Yueyang Zhai, Xulin Wang, Liwei Jiang, Wenfeng Fan, Feng Liu, Jie Qin, Shuangai Wan
The number density of alkali metal vapors and their ratio within hybrid cells is of great significance for the optimal rotation sensitivity of alkali metal-noble gas comagnetometers. To measure the number density of optically thick Rb vapor accurately within a hybrid cell containing optically thin K vapor and optically thick Rb vapor, a novel method combining alkali metal absorption spectroscopy and Raoult's law is proposed in this paper. The relative error between experimental results and results calculated by empirical formula is within ±5% from 365 to 450 K, and the measurement accuracy is improved more than 10 times compared to previous study...
July 10, 2018: Applied Optics
Hongrong Wu, Xiaocheng Zhou, Jidong Li, Xuemei Li, Baowen Li, Wenwen Fei, Jianxin Zhou, Jun Yin, Wanlin Guo
Metal oxides have advantages over the traditional noble metals to be used as substrate materials for surface-enhanced Raman spectroscopy (SERS) with low cost, versatility, and biocompatibility, but their enhancement factors are generally quite low with a poor limit of detection. Here, ultrathin molybdenum dioxide (MoO2 ) nanosheets synthesized by chemical vapor deposition demonstrated in large area are used as SERS substrates with superior signal uniformity in the whole area with a limit of detectable concentration down to 4 × 10-8 m and enhancement factor up to 2...
August 16, 2018: Small
Emre Gürdal, Simon Dickreuter, Fatima Noureddine, Pascal Bieschke, Dieter P Kern, Monika Fleischer
The fabrication and optical characterization of self-assembled arrangements of rough gold nanoparticles with a high area coverage and narrow gaps for surface-enhanced Raman spectroscopy (SERS) are reported. A combination of micellar nanolithography and electroless deposition (ED) enables the tuning of the spacing and size of the noble metal nanoparticles. Long-range ordered quasi-hexagonal arrays of gold nanoparticles on silicon substrates with a variation of the particle sizes from about 20 nm to 120 nm are demonstrated...
2018: Beilstein Journal of Nanotechnology
Asghar Dolatkhah, Purvil Jani, Lee D Wilson
Hybridization of metal NPs with redox-switchable polymer supports not only mitigates their aggregation, but also introduces interfacial electron pathways desirable for catalysis and numerous other applications. The large surface area and surface accessible atoms for noble metal nanoparticles (e.g., Ag, Au, Pt) offer promising opportunities to address challenges in catalysis and environmental remediation. Herein, Ag NPs were supported onto redox-switchable polyaniline (PANI) that acts as an advanced multifunctional conducting template for enhanced catalytic activity...
August 17, 2018: Langmuir: the ACS Journal of Surfaces and Colloids
A Ivanovsky, A Belles, J Criquet, D Dumoulin, P Noble, C Alary, G Billon
During the last few decades, stormwater ponds have become an alternative management practice in order to avoid flooding and to contain rainwater and runoff in urban areas where impervious land cover has increased. A second purpose of stormwater ponds is to improve the quality of runoff water that is usually contaminated with nitrogen, phosphorus, metals and organic micropollutants. Processes used are based on natural methods such as settlement and contribute to minimize the impact of these inputs to the natural aquatic system...
August 13, 2018: Journal of Environmental Management
Gourhari Jana, Sudip Pan, Gabriel Merino, Pratim Kumar Chattaraj
Metal acetylides (MCCH, M = Cu, Ag, Au) were already reported to be experimentally detected in molecular form. Herein, we investigate the possibility of noble gas (Ng) insertion within C-H bond of MCCH and their stability is compared with those of the reported MNgCCH and HCCNgH molecules. Our coupled-cluster computations show that MCCNgH (Ng = Kr, Xe, Rn) systems corresponds to minima on the potential energy surfaces, whereas their lighter analogues do not remain in the chemically bound form. Further, their stability is analyzed with respect to all possible dissociation channels...
August 15, 2018: Journal of Physical Chemistry. A
Parag Adhyapak, Rohini Aiyer, Sreekantha Reddy Dugasani, Hyeong-U Kim, Chung Kil Song, Ajayan Vinu, Venkatesan Renugopalakrishnan, Sung Ha Park, Taesung Kim, Haiwon Lee, Dinesh Amalnerkar
We herein report a simple chemical route to prepare Au-Ag and Ag-Au core-shell bimetallic nanostructures by reduction of two kinds of noble metal ions in the presence of a water-soluble polymer such as poly(vinyl alcohol) (PVA). PVA was intentionally chosen as it can play a dual role of a supporting matrix as well as stabilizer. The simultaneous reduction of metal ions leads to an alloy type of structure. Ag(c)-Au(s) core-shell structures display tendency to form prismatic nanostructures in conjunction with nanocubes while Au(c)-Ag(s) core-shell structures show formation of merely nanocubes...
June 2018: Royal Society Open Science
Nailiang Yang, Hongfei Cheng, Xiaozhi Liu, Qinbai Yun, Ye Chen, Bing Li, Bo Chen, Zhicheng Zhang, Xiaoping Chen, Qipeng Lu, Jingtao Huang, Ying Huang, Yun Zong, Yanhui Yang, Lin Gu, Hua Zhang
Similar to heterostructures composed of different materials, possessing unique properties due to the synergistic effect between different components, the crystal-phase heterostructures, one variety of hetero-phase structures, composed of different crystal phases in monometallic nanomaterials are herein developed, in order to explore crystal-phase-based applications. As novel hetero-phase structures, amorphous/crystalline heterostructures are highly desired, since they often exhibit unique properties, and hold promise in various applications, but these structures have rarely been studied in noble metals...
August 14, 2018: Advanced Materials
Lu Chen, Huijuan Huang, Yuanhui Zheng, Wenhao Sun, Yi Zhao, Paul S Francis, Xuxu Wang
The majority of visible-light photocatalysts show very low hydrogen evolution activity in the absence of noble metal co-catalysts due to their fast carrier recombination rate. Metallic interstitial nitrides have been recognized as excellent hydrogen evolution electrocatalysts and therefore are promising alternative co-catalysts for photocatalytic hydrogen production. Herein we report a low-cost, efficient, noble-metal-free visible-light-driven hydrogen evolution photocatalyst composed of Ni3N/g-C3N4 heterostructures...
August 14, 2018: Dalton Transactions: An International Journal of Inorganic Chemistry
Cong-Cong Shen, Ya-Nan Liu, Xin Wang, Xiao-Xiang Fang, Zhi-Wei Zhao, Nan Jiang, Liu-Bo Ma, Xiao Zhou, Tuck-Yun Cheang, An-Wu Xu
Metal-organic framework (MOF)-based materials possess numerous attractive characteristics; however, the application of MOF-based photocatalysts in the area of visible-light photocatalytic H2 evolution is still in its infancy. Herein, we develop a series of novel UiO-66-NH2-based composites with embedded NiO nanoparticles via solvothermal treatment and subsequent calcination. Their characterizations demonstrate intimate lattice-level contacts between UiO-66-NH2 photocatalysts and NiO nanoparticles. By optimizing each component, even without noble metal loading, the U6N-NiO-2 sample (the weight ratio of NiO to U6N-NiO-2 is theoretically calculated to be ca...
August 14, 2018: Dalton Transactions: An International Journal of Inorganic Chemistry
Shuai Wang, Gyutae Nam, Ping Li, Haeseong Jang, Jia Wang, Min Gyu Kim, Zexing Wu, Xien Liu, Jaephil Cho
Developing highly efficient non-noble metal electrocatalysts for oxygen electrode reactions is highly desirable for industrial scale application in energy related devices. Herein, two new kinds of Ni (POxN3-x)2/NPC and Co (POxN3-x)2/NPC (NPC: N, P-co-doped carbon) are synthesized through a facile post-treatment of nickel- or cobalt-phytic acid xerogel, followed by an annealing procedure under an argon and ammonia atmosphere at 800 °C. The as-prepared catalysts exhibit outstanding catalytic activities for both the oxygen reduction and evolution reactions, which are comparable to those of Pt/C and IrO2...
August 14, 2018: Nanoscale
Mehdi Zareie Yazdan-Abad, Meissam Noroozifar, Nafiseh Alfi
Three dimensional (3-D) self-supported noble metal nanostructures are attractive for their unique properties of high porosity, low density, excellent charge, and mass transfer which increases catalytic activity. Herein, a facile route of preparing two-dimensional (2-D) palladium nanosheets and three-dimensional palladium nanostructure is introduced. By raising the temperature of the reaction mixture, it is possible for Pd nanosheets to change from 2-D into the 3-D structure. Morphology and chemical composition of the nanostructures are characterized by Transition Electron microscopy (TEM), Scanning Electron Microscopy (SEM) and Energy Dispersive X-Ray Spectroscopy (EDX)...
August 4, 2018: Journal of Colloid and Interface Science
Boao Song, Kun He, Yifei Yuan, Soroosh Sharifi-Asl, Meng Cheng, Jun Lu, Wissam A Saidi, Reza Shahbazian-Yassar
Two-dimensional (2D) substrates decorated with metal nanoparticles offer new opportunities to achieve high-performance catalytic behavior. However, little is known on how the substrates control the nucleation and growth processes of the nanoparticles. This paper presents the visualization of dynamic nucleation and growth processes of gold nanoparticles on ultrathin MoS2 nanoflakes by in situ liquid-cell transmission electron microscopy (TEM). The galvanic displacement resulting in Au nuclei formation on MoS2 was observed in real time inside the liquid cell...
August 13, 2018: Nanoscale
Kexin Zhang, Chong Qu, Zibin Liang, Song Gao, Hao Zhang, Bingjun Zhu, Wei Meng, Engang Fu, Ruqiang Zou
Oxygen reduction and evolution reactions as two important electrochemical energy conversion processes in metal-air batteries devices have aroused widespread concern. However, synthesis of low-cost non-noble metal-based bifunctional high performance electrocatalysts is still a great challenge. In this work, we report on the design and synthesis of a novel Co-B/N co-doped carbon with core-shell-structured nanoparticles aligned on graphene nanosheets (denoted as CoTIB-C/G) derived from cobalt tetrakis(1-imidazolyl)borate (CoTIB) and graphene oxide hybrid template...
August 13, 2018: ACS Applied Materials & Interfaces
Tamás Pajkossy, Claus Müller, Timo Jacob
We summarize our results of electrochemical measurements carried out on inert or close-to-inert metals in ionic liquids, with the aim to explore the metal|ionic liquid interface structure. To this we used electrochemical methods: cyclic voltammetry, impedance spectroscopy, potential of zero total charge measurements and structure-sensitive techniques, such as in situ scanning tunneling spectroscopy. The studied systems were mostly single crystals of noble metals in imidazolium-based ionic liquids. The two main findings are: (i) in the potential window where no Faradaic reactions occur, the interfacial capacitance exhibits a frequency dependence due to double-layer rearrangement processes and (ii) in certain cases ordered anion and cation structures exist at the interface...
August 13, 2018: Physical Chemistry Chemical Physics: PCCP
Ramesh Ghosh, Joydip Ghosh, Ruma Das, Larionette P L Mawlong, Kamal Kumar Paul, P K Giri
We report on the fabrication of Ag nanoparticle (NP) decorated mesoporous Si nanowire (NW) heterostructure (HS) by a simple and low cost chemical process. The as-grown Si NWs are mesoporous in nature and the Ag NP decorated Si NWs (Ag@Si NWs) exhibit broadband light emission, ultralow reflectance, efficient photocatalytic degradation of organic dyes and excellent sensitivity for the detection of organic molecules over a wide range of concentration. The broadband white light photoluminescence emission from the bare Si NWs is explained on the basis of quantum confinement effect in Si NCs/NWs and the nonbridging oxygen hole center defects in the SiSiOx interface...
July 29, 2018: Journal of Colloid and Interface Science
Shib Shankar Singha, Suchanda Mondal, Tara Shankar Bhattacharya, Laboni Das, Kamalika Sen, Biswarup Satpati, Kaustuv Das, Achintya Singha
Fabrication of Molybdenum disulfide (MoS2 ) nanostructures and surface functionalization with noble metal nano particles is an emerging field of research as it has potential applications in electronic devices and chemical sensing. Here we report application of gold nanoparticles (AuNPs) decorated MoS2 nanoflowers (Au-MoS2 NFs) as an efficient bio-sensor. MoS2 NFs, synthesized using green synthesis process, are further functionalized with AuNPs to tune their physical properties and make them more appropriate for biological applications...
July 30, 2018: Biosensors & Bioelectronics
Cornelius Krull, Marina Castelli, Prokop Hapala, Dhaneesh Kumar, Anton Tadich, Martina Capsoni, Mark T Edmonds, Jack Hellerstedt, Sarah A Burke, Pavel Jelinek, Agustin Schiffrin
Coordination chemistry relies on harnessing active metal sites within organic matrices. Polynuclear complexes-where organic ligands bind to several metal atoms-are relevant due to their electronic/magnetic properties and potential for functional reactivity pathways. However, their synthesis remains challenging; few geometries and configurations have been achieved. Here, we synthesise-via supramolecular chemistry on a noble metal surface-one-dimensional metal-organic nanostructures composed of terpyridine (tpy)-based molecules coordinated with well-defined polynuclear iron clusters...
August 10, 2018: Nature Communications
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