Controlled Formation of Quantum Size Metal and Semiconductor Particles from Aqueous Solutions

1990 ◽  
Vol 206 ◽  
Author(s):  
Ramesh C. Patel ◽  
Jovan Nedeljkovic ◽  
Olga Micic
Keyword(s):  
Aqueous Solutions ◽  
Chemical Reduction ◽  
Deposition Process ◽  
Metallic Silver ◽  
Uniform Size ◽  
Quantum Size ◽  
Spherical Silica ◽  
Reduction Methods ◽  
Spherical Silica Particles ◽  
Excimer Laser Irradiation

ABSTRACTPhotochemical and chemical reduction methods are described for the controlled formation of metallic silver in aqueous solutions. The former approach is capable of generally depositing a number of metals. When spherical silver bromide particles are the substrates, the resulting silver coated composite particles exhibit optical absorption spectra which vary with the coat thickness as theoretically predicted. In the case of spherical silica particles of uniform size, it was possible to produce both quantum size silver particles supported on silica, as well as a silver coat of variable thickness, depending on the rate of the deposition process. In addition to silica, substrates such as latex and chromium hydroxide could be used.CdS particles with two different particle diameters (50–200 Å and < 30 Å) were subjected to 308 nm excimer laser irradiation at 77 K, and the subsequent charge carrier processes studied by ESR. Dramatic differences in the ESR signals as a function of decreasing particle size could be observed, consistent with the localization of charge carriers on numerous surface sites.

scholarly journals Design, synthesis, and catalytic performance of modified graphene oxide based on a cobalt complex as a heterogenous catalyst for the preparation of aminonaphthoquinone derivatives

RSC Advances ◽  
2021 ◽  
Vol 11 (28) ◽  
pp. 17108-17115
Author(s):  
Mahnaz Mirheidari ◽  
Javad Safaei-Ghomi
Keyword(s):  
Graphene Oxide ◽  
Cobalt Complex ◽  
Catalytic Performance ◽  
Silica Particles ◽  
Design Synthesis ◽  
Spherical Silica ◽  
Modified Graphene Oxide ◽  
Spherical Silica Particles ◽  
Heterogenous Catalyst ◽  
Modified Graphene

GO@f-SiO2@Co is a heterogenous catalyst composed of spherical silica particles grafted on the surface of graphene oxide with ethylenediamine ligands and coordination with Co(ii). We assessed the activity of the catalyst for the synthesis of aminonaphthoquinones.

scholarly journals Tuning the Surface Wettability of Cyclic Olefin Copolymer by Plasma Treatment and Graphene Oxide Deposition and Reduction

Polymers ◽  
2021 ◽  
Vol 13 (14) ◽  
pp. 2305
Author(s):  
Fadi Dawaymeh ◽  
Yawar Abbas ◽  
Maryam Khaleel ◽  
Anas Alazzam ◽  
Nahla Alamoodi
Keyword(s):  
Contact Angle ◽  
Plasma Treatment ◽  
Treatment Duration ◽  
Chemical Reduction ◽  
Surface Wettability ◽  
Oxygen Plasma Treatment ◽  
Microfluidic Channels ◽  
Cyclic Olefin Copolymer ◽  
Cyclic Olefin ◽  
Reduction Methods

Selective altering of surface wettability in microfluidic channels provides a suitable platform for a large range of processes, such as the phase separation of multiphase systems, synthesis of reaction controlled, nanoliter sized droplet reactors, and catalyst impregnation. Herein we study the feasibility to tune the wettability of a flexible cyclic olefin copolymer (COC). Two methods were considered for enhancing the surface hydrophilicity. The first is argon/oxygen plasma treatment, where the effect of treatment duration on water contact angle and COC surface morphology and chemistry were investigated, and the second is coating COC with GO dispersions of different concentrations. For enhancing the hydrophobicity of GO-coated COC surfaces, three reduction methods were considered: chemical reduction by Hydroiodic acid (HI), thermal reduction, and photo reduction by exposure of GO-coated COC to UV light. The results show that as the GO concentration and plasma treatment duration increased, a significant decrease in contact angle was observed, which confirmed the ability to enhance the wettability of the COC surface. The increase in hydrophilicity during plasma treatment was associated with the increase in surface roughness on the treated surfaces, while the increase during GO coating was associated with introducing oxygen-containing groups on the GO-coated COC surfaces. The results also show that the different reduction methods considered can increase the contact angle and improve the hydrophobicity of a GO-coated COC surface. It was found that the significant improvement in hydrophobicity was related to the reduction of oxygen-containing groups on the GO-coated COC modified surface.

A novel electrochemical comparative sensing interface of MgO nanoparticles synthesized by different methods

2017 ◽  
Vol 233 (3) ◽  
pp. 753-762 ◽  
Author(s):  
Utkarsh Jain ◽  
CS Pundir ◽  
Shaivya Gupta ◽  
Nidhi Chauhan
Keyword(s):  
Electrochemical Impedance ◽  
Chemical Reduction ◽  
Cost Effective ◽  
Green Technology ◽  
Mgo Nanoparticles ◽  
Transmission Electron ◽  
Impedance Spectroscopy Study ◽  
Vis Spectroscopy ◽  
Reduction Methods ◽  
Average Size

Recent advancements in nanotechnology, for the biosynthesis of metal nanoparticles through enormous techniques, showed multidimensional developments. One among many facets of nanotechnology is to procure and adopt new advancements for green technology over chemical reduction synthesis. This adaptation for acquiring green nanotechnology leads us to a new dimension of nanobiotechnology. In order to imply one such efforts, in this study the emphasis is being laid on the synthesis of MgO nanoparticles using green technology and eliminating chemical reduction methods. Different characterization techniques such as UV–Vis spectroscopy, transmission electron microscopy, and dynamic light scattering were used to carry out the experiments. The average size of MgO nanoparticles were obtained in the range of 85–95 nm, when synthesized by various sources. The extracts of plants were capable of producing MgO nanoparticles efficiently and exhibited good results during cyclic voltammetry and electrochemical impedance spectroscopy study. The electrode modified with MgO nanoparticles (plant extract) showed good stability (90 days) and high conductivity. This study reports cost-effective and environment-friendly method for synthesis of MgO nanoparticles using plant extracts. The process is rapid, simple, and convenient and can be used as an alternative to chemical method.

Preparation and Characterization of Bulk and Supported NiB Amorphous Alloy Catalysts with Different Particle Sizes

2007 ◽  
Vol 121-123 ◽  
pp. 637-640
Author(s):  
Lai Jun Wang ◽  
Wei Li ◽  
M.H. Zhang ◽  
K.Y. Tao
Keyword(s):  
Amorphous Alloy ◽  
Electroless Plating ◽  
Chemical Reduction ◽  
Reaction System ◽  
Catalytic Performance ◽  
Ni Catalyst ◽  
Particle Sizes ◽  
Raney Ni ◽  
Reduction Methods ◽  
Alloy Catalysts

A series of bulk and supported NiB amorphous alloy catalysts with different particle sizes were prepared by different chemical reduction methods. By adding a certain volume of NH3 to the reaction system and adjusting the reaction temperature, respectively, the velocity of the reaction between Ni2+ and BH4 - could be controlled and the NiB alloys with particle sizes ranging from 10 to 400nm were obtained. A novel method to prepare the supported NiB catalyst, the powder electroless plating method was also studied. The bulk and supported NiB catalysts were characterized by XRD, ICP and TEM. Hydrogenation of sulfolene was selected as the probe reaction to investigate their catalytic performance. The results revealed that the NiB/MgO prepared by Ag inducing electroless plating showed much higher catalytic activity than Raney Ni catalyst, and the powder electroless plating was a promising method to prepare the supported NiB amorphous alloy catalysts.

Magnetic behavior of superparamagnetic Fe nanocrystals confined inside submicron-sized spherical silica particles

2004 ◽  
Vol 69 (9) ◽  
Author(s):  
P. Tartaj ◽  
T. González-Carreño ◽  
O. Bomatí-Miguel ◽  
C. J. Serna ◽  
P. Bonville
Keyword(s):  
Magnetic Behavior ◽  
Silica Particles ◽  
Spherical Silica ◽  
Spherical Silica Particles
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