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Noble metal

Xinzhang Lin, Chao Liu, Xuemei Fu, Jiahui Huang
Metal ions have important impact on the precise controlling synthesis and atomic structural arrangement of noble metal nanoclusters. In this work, it is the first time to reveal metal ion effect on the isomer generation of metal nanoclusters. Compared with the previous Ag23 nanoclusters with two FCC unit cells twisting 27°, the Ag23 isomer had a higher-symmetry structure with two FCC unit cells almost overlapping. In addition, Uv-vis absorption spectrum of the isomer showed a slight redshift of ~14 nm. The redshift might be because of the modulation of electronic structure which derived from fine-tuned crystal structure...
February 13, 2019: Chemistry, An Asian Journal
Krishna Prasad Gannavarapu, Samar Azizighannad, Sai Muthukumar V, Somenath Mitra, Rajesh Babu Dandamudi
Herein we report a microwave assisted, fungal (Ganoderma lucidum) extract mediated synthesis of noble metal decorated reduced graphene oxide(r-GO). The carbon to oxygen ratio increased from 1.46 in GO to 2.72 in r-GO. The electron rate transfer capabilities of Pt, Pd, Ru, Pt-Pd and Pt- Ru decorated r- GO were tested in ferri-ferro coupling reaction. Excellent electrochemical behaviour were observed in their ability to oxidize hydrazine, reduce H2 O2 , as well as oxygen reduction in alkaline medium and hydrogen evolution in acidic medium...
December 19, 2018: ChemistrySelect
Huan Liu, Cheng-Yan Xu, Yue Du, Fei-Xiang Ma, Yue Li, Jing Yu, Liang Zhen
Development of hydrogen as clean and efficient energy carrier for future is imperative. Water electrolysis, is considered as one of the most promising ways to realize large-scaled hydrogen production. However, a big obstacle of it is to reduce the electric energy consumption for water oxidation in the anode. Engineering of hierarchical architectures on the electrocatalysts could provide abundant active sites and thus boost the sluggish reaction kinetics of water oxidation. Herein, a sequential synthesis method is developed for in-situ growth of ultrathin Co9 S8 nanosheets vertically aligned on N and S co-doped reduced graphene oxide (Co9 S8 /N,S-rGO) as novel and efficient electrocatalysts for water splitting...
February 13, 2019: Scientific Reports
Hui-Li Tan, Sin-Yeang Teow, Janarthanan Pushpamalar
Challenges in organ transplantation such as high organ demand and biocompatibility issues have led scientists in the field of tissue engineering and regenerative medicine to work on the use of scaffolds as an alternative to transplantation. Among different types of scaffolds, polymeric hydrogel scaffolds have received considerable attention because of their biocompatibility and structural similarity to native tissues. However, hydrogel scaffolds have several limitations, such as weak mechanical property and a lack of bioactive property...
February 11, 2019: Bioengineering
Arkadiusz Ciesielski, Lukasz Skowronski, Marek Trzcinski, Ewa Górecka, Wojciech Pacuski, Tomasz Szoplik
Noble metal nanolayers on flat substrates are often deposited with the use of semiconductor interlayers, which may strongly interact with the noble metal overlayer. We investigated the crystallinity, atomic concentration profile and optical parameters of ≈35 nm-thick silver and gold layers deposited on glass substrates with 2 nm-thick tellurium or selenium interlayers. Our study, based on X-ray reflectometry (XRR), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and ellipsometric measurements, showed that using either of these interlayers introduces strain in nanocrystals of both plasmonic films...
2019: Beilstein Journal of Nanotechnology
Manyi Gao, Yongsheng Yu, Weiwei Yang, Ji Li, Shichong Xu, Ming Feng, Haibo Li
The development of a robust and low-cost non-noble metal catalyst for photocatalytic H2 evolution is of great importance for practical applications. In this study, monodisperse Ni nanoparticles of controlled sizes were prepared by a facile method and anchored on graphitic carbon nitride (g-C3N4) nanosheets via a self-assembly route. The noble-metal-free Ni/g-C3N4 composite catalysts exhibit excellent photocatalytic activities for the hydrolytic dehydrogenation of ammonia borane (AB) under visible light. An optimum AB hydrolysis rate was obtained when the size of the Ni NPs was 3...
February 11, 2019: Nanoscale
Sudip Pan, Gourhari Jana, Gabriel Merino, Pratim K Chattaraj
This Review presents the current status of the noble gas (Ng)-noble metal chemistry, which began in 1977 with the detection of AuNe+ through mass spectroscopy and then grew from 2000 onwards; currently, the field is in a somewhat matured state. On one side, modern quantum chemistry is very effective in providing important insights into the structure, stability, and barrier for the decomposition of Ng compounds and, as a result, a plethora of viable Ng compounds have been predicted. On the other hand. experimental achievement also goes beyond microscopic detection and characterization through spectroscopic techniques and crystal structures at ambient temperature; for example, (AuXe4 )2+ (Sb2 F11 - )2 have also been obtained...
February 2019: ChemistryOpen
Yitao Dai, Pengju Ren, Yaru Li, Dongdong Lv, Yanbin Shen, Yongwang Li, Hans Niemantsverdriet, Flemming Besenbacher, Hongwei Xiang, Weichang Hao, Nina Lock, Xiaodong Wen, James P Lewis, Ren Su
Selective oxidation of primary alcohols to aldehydes by O2 instead of stoichiometric oxidants (e.g., Mn7+, Cr6+ and Os4+) is an important but challenging process. Most heterogeneous catalytic systems (thermal- and photo-catalysis) require noble metals or harsh reaction conditions. Here we show that the Bi24O31Br10(OH)δ photocatalyst is very efficient in selective oxidation of a series of aliphatic (carbon chain from C1 to C10) and aromatic alcohols to their corresponding aldehydes/ketones under visible light irradiation in air at room temperature, which would be challenging for conventional thermal- and light-driven processes...
February 8, 2019: Angewandte Chemie
Christian Schöttle, Erjia Guan, Alexander Okrut, Nicolás A Grosso-Giordano, Andrew Palermo, Andrew Solovyov, Bruce C Gates, Alexander Katz
Although essentially molecular, noble metal species provide active sites and highly tunable platforms for design of supported catalysts, the susceptibility of the metals to reduction and aggregation and the consequent loss of catalytic activity and selectivity limit opportunities for their application. Here, we demonstrate a new construct to stabilize supported molecular noble metal catalysts, taking advantage of sterically bulky ligands on the metal that serve as surrogate supports and isolate the active sites under conditions involving steady-state catalytic turnover in a reducing environment...
February 8, 2019: Journal of the American Chemical Society
Fengxia Wu, Wenxin Niu, Jianping Lai, Wei Zhang, Rafael Luque, Guobao Xu
Developing electrocatalysts with ultrathin nanostructures and high mesoporosity is a relevant high-priority research direction toward enhancing the performance of noble metals. Herein, mesoporous, highly excavated octahedral PtCu3 nanostructures are prepared by a facile one-pot synthesis. The mesoporous, highly excavated octahedral PtCu3 nanostructures are built with mutually perpendicular interlaced mesoporous nanosheets with a thickness of ≈4.5 nm. Benefiting from its mesoporous features, three-dimensional (3D) open surfaces, ultrathin nanosheets, and a Cu-rich surface, PtCu3 exhibits excellent electrocatalytic performance and high antipoisoning activity toward the methanol oxidation reaction...
February 6, 2019: Small
Yaqian Liu, Zhihui Shao, Yujie Wang, Lijin Xu, Zhiyong Yu, Qiang Liu
Isobutanol serves as an ideal gasoline additive due to its good compatibility with current engine technology, high energy density and high octane number. Herein, we report an efficient and selective Mn-catalyzed upgrading of ethanol with methanol into isobutanol. This is the first example of deoxgenative coupling of lower alcohols to isobutanol by using a homogeneous non-noble-metal catalyst. This transformation could proceed at very low catalyst loading with high turnover number (9233) and up to 96% isobutanol selectivity was also reached...
February 5, 2019: ChemSusChem
Linlin Xu, Danye Liu, Dong Chen, Hui Liu, Jun Yang
Controlling of the size and/or shape of noble metal nanoparticles (NMNPs) is crucial to make use of their unique properties and to optimize their performance for a given application. Within the past decades, the development of wet-chemistry methods enables fine tailoring of the size and morphology of NMNPs. We herein devote this review to introduce the wet-chemistry-based methods for the size and shape-controlled synthesis of rhodium (Rh) NPs. We start with a summarization of the wet-chemistry-based approaches developed for producing Rh NPs and then focus on recent fascinating advances in their size- and shape-control in the aspects of kinetic and thermodynamic regimes depending on the synthetic conditions...
January 2019: Heliyon
Weicong Wang, Xiang Li, Tianou He, Yaming Liu, Mingshang Jin
Synthesis of Pt nanoshells on substrates can increase the utilization efficiency of Pt atoms and reduce the amount of Pt required in a process where it is essential. However, the growth of Pt nanoshells still faces challenges in tailoring the exposed crystal facets with which to control their catalytic activity and selectivity on a given substrate. In this work, we demonstrate a simple and convenient method capable for generating Pt octahedral islands with tunable sizes and densities on Pd cubic seeds by manipulating the deposition rate, which could be easily implemented and potentially applied to other noble metals...
February 5, 2019: Nano Letters
Jianping Xin, Hua Tan, Zhihe Liu, Lili Zhao, Junfeng Xie, Yuanhua Sang, Weijia Zhou, Aizhu Wang, Hong Liu, Jian-Jun Wang
Electrocatalysts are of significant importance for hydrogen production via water splitting. To replace noble metal based electrocatalysts, exploring new counterparts is critical for their large-scale and widespread deployment. In this paper, we report the synthesis of nickel-cobalt selenite (Ni0.5Co0.5SeO3) networks on nickel foam with promising electrocatalytic performance through a facile electrodeposition method. The networked structure built with interconnected nanosheets along with the three-dimensional backbone of nickel foam is able to provide a large surface area for the reaction to take place and simultaneously offer connected channels for charge carriers to pass through, consequently realizing the enhancement of oxygen evolution reaction (OER) electrocatalytic activity...
February 5, 2019: Nanoscale
Yuzhi Xu, Si-Yang Liu, Junling Liu, Li Zhang, Danping Chen, Jun Chen, Yingjun Ma, Jie-Peng Zhang, Zong Dai, Xiaoyong Zou
Metal-organic frameworks (MOFs) for enzyme immobilization have already shown superior tunable and designable characteristics, however, their devisable responsive properties have rarely been exploited. Herein, we integrated a responsive MOF into MOF-enzyme composite to propose an "all-in-one" multifunctional composite with catalytic and luminescence functions implemented within a single particle. As a proof-of-concept, glucose oxidase (GOx) was in situ encapsulated within an oxygen (O₂)-sensitive, noble-metal-free luminescent Cu(I) triazolate framework (MAF-2), namely GOx@MAF-2...
February 4, 2019: Chemistry: a European Journal
Khang June Lee, Shinho Kim, Woonggi Hong, Hamin Park, Min Seok Jang, Kyoungsik Yu, Sung-Yool Choi
Plasmonic coupling provides a highly localized electromagnetic field in the gap of noble metals when illuminated by a light. The plasmonic field enhancement is generally known to be inversely proportional to the gap distance. Given such a relation, reducing the gap distance appears to be necessary to achieve the highest possible field enhancement. At the sub-nanometer scale, however, quantum mechanical effects have to be considered in relation to plasmonic coupling. Here, we use graphene as a spacer to observe plasmonic field enhancement in sub-nanometer gap...
February 4, 2019: Scientific Reports
Sundar Kunwar, Mao Sui, Puran Pandey, Zenan Gu, Sanchaya Pandit, Jihoon Lee
Noble metallic nanoparticles (NPs) can exhibit valuable properties such as localized surface plasmon resonance (LSPR) and large surface to volume ratio, which can find various optoelectronic and catalytic applications. In this work, the improved configuration and uniformity of platinum (Pt) NPs are demonstrated by using a sacrificial indium (In) layer via the enhanced solid state dewetting of In-Pt bilayers on sapphire (0001). In a sharp contrast to the conventional dewetting of intrinsic Pt film, the introduction of In component can significantly enhance the global dewetting process and thus can result in the fabrication of well-defined Pt NPs with the improved uniformity...
February 4, 2019: Scientific Reports
Liyan Zhou, Shancheng Yan, Haizeng Song, Han Wu, Yi Shi
Tungsten Disulfide (WS2 ) is considered to be a promising Hydrogen Evolution Reaction (HER) catalyst to replace noble metals (such as Pt and Pd). However, progress in WS2 research has been impeded by the inertness of the in-plane atoms during HER. Although it is known that microstructure and defects strongly affect the electrocatalytic performance of catalysts, the understanding of such related catalytic origin still remains a challenge. Here, we combined a one-pot synthesis method with wet chemical etching to realize controlled cobalt doping and tunable morphology in WS2 ...
February 4, 2019: Scientific Reports
Wei Zhu, Achraf Noureddine, Jane Y Howe, Jimin Guo, C Jeffrey Brinker
Supported ultrasmall noble metal nanocluster-based (UNMN-based) catalysts are one of the most important classes of solid materials for heterogeneous catalysis. In this work, we present a novel strategy for the controlled synthesis of ligand-free UNMN nanocatalysts based on in situ reduction of a palladium-based (Pd-based) metal-organic cage (MOC) confined within monosized, thiol-modified mesoporous silica nanoparticle (MSN) supports. By taking advantage of the high mutual solubility of MOCs and MSNs in DMSO and the strong interactions between the thiol-modified MSN pore wall and MOC surface, a good dispersion of MOC molecules was achieved throughout the MSN support...
February 8, 2019: Nano Letters
Teng Liu, Peng Li, Na Yao, Gongzhen Cheng, Wei Luo, Shengli Chen, Yadong Yin
Although electrocatalysts based on transition metal phosphides (TMPs) with cationic/anionic doping have been widely studied for hydrogen evolution reaction (HER), the origin of performance enhancement still remains elusive mainly due to the random dispersion of dopants. Herein, we report a controllable partial phosphorization strategy to generate CoP species within the Co-based metal-organic framework (Co-MOF). Density functional theory calculations and experimental results reveal that the electron transfer from CoP to Co-MOF through N-P/N-Co bonds could lead to the optimized adsorption energy of H2O (∆GH2O*) and hydrogen (∆GH*), which, together with the unique porous structure of Co-MOF, contributes to the remarkable HER performance with an overpotential of 49 mV at a current density of 10 mA cm-2 in 1 M phosphate buffer solution (PBS, pH = 7...
February 4, 2019: Angewandte Chemie
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