scholarly journals Synthesis of Metallic Nanocrystals: From Noble Metals to Base Metals

Materials ◽  
2019 ◽  
Vol 12 (9) ◽  
pp. 1497 ◽  
Author(s):  
Liuyang Bai ◽  
Yuge Ouyang ◽  
Jun Song ◽  
Zhi Xu ◽  
Wenfu Liu ◽  
...  
Keyword(s):  
Base Metal ◽  
Noble Metals ◽  
Oriented Attachment ◽  
Synthesis Methods ◽  
Base Metals ◽  
Catalytic Activities ◽  
Metal Nanocrystals ◽  
Development Direction ◽  
Specific Synthesis ◽  
Oswald Ripening

Metallic nanocrystals exhibit superior properties to their bulk counterparts because of the reduced sizes, diverse morphologies, and controllable exposed crystal facets. Therefore, the fabrication of metal nanocrystals and the adjustment of their properties for different applications have attracted wide attention. One of the typical examples is the fabrication of nanocrystals encased with high-index facets, and research on their magnified catalytic activities and selections. Great accomplishment has been achieved within the field of noble metals such as Pd, Pt, Ag, and Au. However, it remains challenging in the fabrication of base metal nanocrystals such as Ni, Cu, and Co with various structures, shapes, and sizes. In this paper, the synthesis of metal nanocrystals is reviewed. An introduction is briefly given to the metal nanocrystals and the importance of synthesis, and then commonly used synthesis methods for metallic nanocrystals are summarized, followed by specific examples of metal nanocrystals including noble metals, alloys, and base metals. The synthesis of base metal nanocrystals is far from satisfactory compared to the tremendous success achieved in noble metals. Afterwards, we present a discussion on specific synthesis methods suitable for base metals, including seed-mediated growth, ligand control, oriented attachment, chemical etching, and Oswald ripening, based on the comprehensive consideration of thermodynamics, kinetics, and physical restrictions. At the end, conclusions are drawn through the prospect of the future development direction.

scholarly journals Current Strategies for Noble Metal Nanoparticle Synthesis

2021 ◽  
Vol 16 (1) ◽  
Author(s):  
Giyaullah Habibullah ◽  
Jitka Viktorova ◽  
Tomas Ruml
Keyword(s):  
Noble Metal ◽  
Noble Metals ◽  
Drug Carriers ◽  
Industrial Applications ◽  
Metal Nanoparticle ◽  
Noble Metal Nanoparticles ◽  
Synthesis Methods ◽  
Gold And Silver Nanoparticles ◽  
Diverse Range ◽  
The Past

AbstractNoble metals have played an integral part in human history for centuries; however, their integration with recent advances in nanotechnology and material sciences have provided new research opportunities in both academia and industry, which has resulted in a new array of advanced applications, including medical ones. Noble metal nanoparticles (NMNPs) have been of great importance in the field of biomedicine over the past few decades due to their importance in personalized healthcare and diagnostics. In particular, platinum, gold and silver nanoparticles have achieved the most dominant spot in the list, thanks to a very diverse range of industrial applications, including biomedical ones such as antimicrobial and antiviral agents, diagnostics, drug carriers and imaging probes. In particular, their superior resistance to extreme conditions of corrosion and oxidation is highly appreciated. Notably, in the past two decades there has been a tremendous advancement in the development of new strategies of more cost-effective and robust NMNP synthesis methods that provide materials with highly tunable physicochemical, optical and thermal properties, and biochemical functionalities. As a result, new advanced hybrid NMNPs with polymer, graphene, carbon nanotubes, quantum dots and core–shell systems have been developed with even more enhanced physicochemical characteristics that has led to exceptional diagnostic and therapeutic applications. In this review, we aim to summarize current advances in the synthesis of NMNPs (Au, Ag and Pt).

scholarly journals Economic Geology Models 5. Specialty, Critical, Battery, Magnet and Photovoltaic Materials: Market Facts, Projections and Implications for Exploration and Development

2021 ◽  
Vol 48 (2) ◽  
Author(s):  
Laura Simandl ◽  
George J. Simandl ◽  
Suzanne Paradis
Keyword(s):  
Base Metal ◽  
Industrial Development ◽  
Objective Assessment ◽  
Green Technology ◽  
Metal Extraction ◽  
Base Metals ◽  
Considerable Uncertainty ◽  
Photovoltaic Materials ◽  
Small Market ◽  
Specialty Metals

Many exploration companies are now focusing on specialty materials that are associated with so-called ‘green technology’. These include ‘battery materials’, ‘magnet materials’ and ‘photovoltaic materials’, and many such commodities are also broadly labelled as ‘critical materials’ because they are seen as vital for industrial development, societal needs or national security. The definitions used for such materials are not always consistent among jurisdictions or across industry, and this paper attempts to clarify the criteria and address some common misconceptions. The distinction between major minerals (e.g. base metals) and ‘specialty materials’ (i.e. those mined or produced in much smaller amounts) is particularly important.   The markets for many specialty materials are growing faster than those for traditional ferrous, precious and base metals and they are often portrayed as excellent long-term investment opportunities. However, the small market bases for specialty materials and considerable uncertainty around growth projections (especially related to material substitutions and rapid technological change) need to be taken into consideration for objective assessment of the development potential of any proposed project, establishment of new supply chains by major corporations, and responsible decision-making (mineral policy) by government. In the short-term, projects aimed at specialty materials (materials with a small market base) cannot benefit from economy of scale, and their development hinges on commercially proven metallurgical processes, unless they are supported by governments or end-users.   Several specialty metals (e.g. germanium, indium, cadmium, and cobalt) are commonly obtained as by-product of base metal extraction. In such cases, systematic testing of base metal ores for their specialty metal content may justify the addition of relevant recovery circuits to existing smelters. If positive results are obtained, the need for targeting new sources of such specialty metals as primary exploration targets may be reduced or eliminated.   Where market conditions permit and concerns about the future availability of materials seem reliable, grass-roots exploration for specialty materials is warranted, and pre-competitive government involvement may be justified to promote such development efforts.

scholarly journals Progress in Vinyl Acetate

CONVERTER ◽  
2021 ◽  
pp. 861-867
Author(s):  
Heng Ma
Keyword(s):  
Vinyl Acetate ◽  
Synthesis Method ◽  
Raw Material ◽  
Organic Chemical ◽  
Synthesis Methods ◽  
Advantages And Disadvantages ◽  
Production Route ◽  
Film Adhesive ◽  
Development Direction ◽  
Adhesive Coating

Vinyl acetate is an organic chemical raw material of great industrial value. It is widely used in synthetic film, adhesive, coating and textile slurry. The production route of vinyl acetate is introduced, and the advantages and disadvantages of synthesis methods of vinyl acetate method, acetylene method, EDA cracking method, base synthesis method and Halcon method are compared. The method of carbide acetylene has high economic efficiency, low energy consumption and good environmental protection, proposing the development direction of ethylene acetate production technology.

scholarly journals Mesoporous Nanocast Electrocatalysts for Oxygen Reduction and Oxygen Evolution Reactions

Inorganics ◽  
2019 ◽  
Vol 7 (8) ◽  
pp. 98 ◽  
Author(s):  
Tatiana Priamushko ◽  
Rémy Guillet-Nicolas ◽  
Freddy Kleitz
Keyword(s):  
Oxygen Reduction ◽  
High Activity ◽  
Oxygen Evolution ◽  
Noble Metal ◽  
Noble Metals ◽  
Low Cost ◽  
High Surface ◽  
Clean Energy ◽  
Production Costs ◽  
Synthesis Methods

Catalyzed oxygen evolution and oxygen reduction reactions (OER and ORR, respectively) are of particular significance in many energy conversion and storage processes. During the last decade, they emerged as potential routes to sustain the ever-growing needs of the future clean energy market. Unfortunately, the state-of-the-art OER and ORR electrocatalysts, which are based on noble metals, are noticeably limited by a generally high activity towards one type of reaction only, high costs and relatively low abundance. Therefore, the development of (bi)functional low-cost non-noble metal or metal-free electrocatalysts is expected to increase the practical energy density and drastically reduce the production costs. Owing to their pore properties and high surface areas, mesoporous materials show high activity towards electrochemical reactions. Among all synthesis methods available for the synthesis of non-noble mesoporous metal oxides, the hard-templating (or nanocasting) approach is one of the most attractive in terms of achieving variable morphology and porosity of the materials. In this review, we thus focus on the recent advances in the design, synthesis, characterization and efficiency of non-noble metal OER and ORR electrocatalysts obtained via the nanocasting route. Critical aspects of these materials and perspectives for future developments are also discussed.

scholarly journals Direct Base-Assisted C‒H Cyclonickelation of 6-Phenyl-2,2′-bipyridine

Molecules ◽  
2020 ◽  
Vol 25 (4) ◽  
pp. 997
Author(s):  
Nicolas Vogt ◽  
Vasily Sivchik ◽  
Aaron Sandleben ◽  
Gerald Hörner ◽  
Axel Klein
Keyword(s):  
Elevated Temperature ◽  
Title Compound ◽  
Noble Metals ◽  
Oxidative Addition ◽  
Base Metals ◽  
Base Pairs ◽  
Reaction Conditions ◽  
Wide Range ◽  
The World ◽  
First Time

The organonickel complexes [Ni(Phbpy)X] (X = Br, OAc, CN) were obtained for the first time in a direct base-assisted arene C(sp2)–H cyclometalation reaction from the rather unreactive precursor materials NiX2 and HPhbpy (6-phenyl-2,2′-bipyridine) or from the versatile precursor [Ni(HPhbpy)Br2]2. Different from previously necessary C‒Br oxidative addition at Ni(0), an extended scan of reaction conditions allowed quantitative access to the title compound from Ni(II) on synthetically useful timescales through base-assisted C‒H activation in nonpolar media at elevated temperature. Optimisation of the reaction conditions (various bases, solvents, methods) identified 1:2 mixtures of acetate and carbonate as unrivalled synergetic base pairs in the optimum protocol that holds promise as a readily usable and easily tuneable access to a wide range of direct nickelation products. While for the base-assisted C‒H metalation of the noble metals Ru, Ir, Rh, or Pd, this acetate/carbonate method has been established for a few years, our study represents the leap into the world of the base metals of the 3d series.

Evaluation of Optimal Conditions for D-Tube Brazing

2008 ◽  
Vol 33-37 ◽  
pp. 1345-1350 ◽  
Author(s):  
W.K. Joo ◽  
Yi Qi Wang ◽  
H.T. Yang ◽  
W.C. Lee ◽  
C.Y. Sim ◽  
...  
Keyword(s):  
Tensile Test ◽  
Base Metal ◽  
Maximum Stress ◽  
Filler Metal ◽  
Metal Layer ◽  
Stress And Strain ◽  
Base Metals ◽  
Element Analysis ◽  
Better Than ◽  
Counter Diffusion

The microstructures and mechanical properties of OFHC copper/STKM 11A for D-tube joints brazed using BAg filler metal at 870 °C for 20 minutes in NH3 atmospheres were performed. Interfacial microstructures were observed in reaction layer. A brazing strength causes of decline with defects of pin hole and base metal by lack of penetration. In tensile test, the properties of joints clearance of 0.01mm are better than other joints clearance that has yield strength of elasticity area with the brazing length of 2.5mm, and also suitable for the case of brazing length of 5.0mm. According to the results of FEA (finite element analysis) on the tensile test, the maximum stress and strain were generated apart from the interface in large deformation. Diffused layer was formed by counter diffusion action of base metal and filler metal layer, and crack between two base metals was not discovered. This is the main reason that fracture of test piece does not appear in copper base metal, and brazing department forms good junctures.

Search and Synthesis of New Family of Quasicrystals

2003 ◽  
Vol 805 ◽  
Author(s):  
Tsutomu Ishimasa ◽  
Shiro Kashimoto ◽  
Ryo Maezawa
Keyword(s):  
Electron Concentration ◽  
Noble Metals ◽  
Alloy Composition ◽  
Starting Material ◽  
Icosahedral Quasicrystal ◽  
Base Metals ◽  
Transition Elements ◽  
New Family ◽  
Cast Alloys ◽  
P Type

ABSTRACTStarting from the Zn17Sc3 cubic approximant, new icosahedral quasicrystal was searched by substituting Zn by other metals, M, at the alloy composition of Zn75M10Sc15. In the cases of M = Mn, Fe, Co, Ni, Pd, Pt, Ag and Au, new P-type quasicrystals were discovered in as-cast alloys. In the cases of M = Fe, Co, Ni, Pd and Ag, the quasicrystals are thermodynamically stable at approximately 700 °C. This result indicates that use of an approximant crystal as a starting material is very efficient way to search new quasicrystal alloy, and many kinds of metals stabilize the quasicrystal structures; i.e. noble metals and transition elements including Mn, Fe, Co and Ni in addition to Mg. Taking the variety in base metals of Tsai-type approximants into account, this variety in additional components suggests many possibilities of undiscovered quasicrystals. The equality ofthe electron concentration, ela ≈ 2.1, in Hume-Rothery rule may be a guide to these quasicrystals.

Effects of synthesis methods on catalytic activities of CoO x –TiO 2 for low-temperature NH 3 -SCR of NO

2017 ◽  
Vol 54 ◽  
pp. 277-287 ◽  
Author(s):  
Li Zhu ◽  
Yiqing Zeng ◽  
Shule Zhang ◽  
Jinli Deng ◽  
Qin Zhong
Keyword(s):  
Low Temperature ◽  
Synthesis Methods ◽  
Catalytic Activities ◽  
Scr Of No
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