scholarly journals Nanoporous gold assemblies of calixarene-phosphine-capped colloids

2017 ◽  
Vol 53 (79) ◽  
pp. 10870-10873 ◽  
Author(s):  
Christian Schöttle ◽  
Ezra L. Clark ◽  
Audrey Harker ◽  
Andrew Solovyov ◽  
Alexis T. Bell ◽  
...  
Keyword(s):  
Surface Area ◽  
High Surface ◽  
High Surface Area ◽  
Volume Ratio ◽  
Nanoporous Gold

Synthesis of high surface-area colloidal assemblies of calixarene-phosphine-capped nanoporous gold with a remarkably high surface-to-volume ratio is reported.

scholarly journals Morphological evolution of Pt-modified nanoporous gold after thermal coarsening in reductive and oxidative environments

2020 ◽  
Vol 4 (1) ◽  
Author(s):  
A. A. El-Zoka ◽  
B. Langelier ◽  
G. A. Botton ◽  
R. C. Newman
Keyword(s):  
Surface Area ◽  
Morphological Evolution ◽  
High Surface ◽  
High Surface Area ◽  
Volume Ratio ◽  
Atom Probe ◽  
Nanoporous Gold ◽  
Atomic Scale ◽  
Thermal Coarsening

AbstractNanoporous gold made by dealloying AgAuPt (NPG-Pt) has been shown to exhibit several interesting catalytic properties, tied to its exceptionally high surface area; however, structural degradation may occur owing to thermal coarsening. To understand the effect of atmosphere chemistry on thermal coarsening and degradation, and means of limiting it, this study focuses on the high-resolution characterization of NPG-Pt layers coarsened in reductive Ar-H2 atmosphere, and in oxidative air. Atom probe tomography (APT) analysis is performed on NPG-Pt, coarsened separately in either Ar-H2 or air, to characterize the atomic-scale chemical changes in the nanoligaments and to develop a mechanistic view of the inherent processes. A tendency of Ag to segregate to the surface during coarsening is found to lead to complete elimination of the nanoligament core-shell structures in both cases. Large Pt segregates form during coarsening in Ar-H2, but under the surface of the ligaments, having relatively little effect on the coarsening rate. The oxygen-induced segregation of Pt was observed to cause the inhibition of thermal coarsening after minor loss in surface area-to-volume ratio. Findings in this paper help in understanding further the thermal coarsening of heterogeneous nanomaterials made by dealloying, and the pertinent factors that come into play in different chemical environments.

scholarly journals Enhanced photoelectrochemical water splitting performance using morphology-controlled BiVO4 with W doping

2017 ◽  
Vol 8 ◽  
pp. 2640-2647 ◽  
Author(s):  
Xin Zhao ◽  
Zhong Chen
Keyword(s):  
Surface Area ◽  
Light Absorption ◽  
Charge Separation ◽  
High Surface ◽  
High Surface Area ◽  
Charge Injection ◽  
Volume Ratio ◽  
Solvent Ratio ◽  
Photoelectrochemical Performance ◽  
Interfacial Charge

Nanostructures exhibit numerous merits to improve the efficiency in solar-to-energy conversion. These include shortened carrier collection pathways, an increased volume ratio between depletion layer and bulk, enhanced light capture due to multiple light scattering in nanostructures, and a high surface area for photochemical conversion reactions. In this study, we describe the synthesis of morphology-controlled W-doped BiVO4 by simply tuning the solvent ratio in precursor solutions. Planar and porous W-doped BiVO4 thin films were prepared and compared. The porous film, which exhibits increased surface area and enhanced light absorption, has displayed enhanced charge separation and interfacial charge injection. Our quantitative analysis showed an enhancement of about 50% of the photoelectrochemical performance for the porous structure compared to the planar structure. This enhancement is attributed to improved light absorption (13% increase), charge separation (14% increase), and interfacial charge injection (20% increase).

scholarly journals Nanotechnology and Its Applications to Medicine: an over view

QJM ◽  
2020 ◽  
Vol 113 (Supplement_1) ◽  
Author(s):  
H Ibrahim
Keyword(s):  
Surface Area ◽  
High Surface ◽  
High Surface Area ◽  
Volume Ratio ◽  
Electrospinning Process ◽  
Nano Particles ◽  
High Production Rate ◽  
Nano Fiber ◽  
Nano Medicine ◽  
Bio Compatibility

Abstract Nowadays there are more interesting with nanotechnology and its applications in several sectors specially in medicine for diagnoses, therapeutic and research biomedical tools. It can be defined as any process or technique used to produce material in nano-scale structure with particle size ranged from 1-100 nm. The utilization of nanotechnology in human health benefits known as nano medicine. So that nanotechnology has firmly entered the drug delivery realm to maximize drug therapeutic activity and minimize its undesirable side effects. Herein we deal with both nanoparticles and nano-fibers and their applications in medical field. Nano-particles have unique properties from its small size with high surface area therefore it provides larger than particle numbers from that prepared with convention methods. In addition, nanoparticles can be used to improve various drug bio-availability from its biodegradability and bio-compatibility. Nano-fibers have huge surface area to volume ratio which increase its performance in several applications. Nano-fiber produced via electrospinning process (simple and have high production rate). It can be used in many applications such as water filtration, tissue engineering scaffold, wounds, fiber composites, drug release and protective clothes.

Growth of Carbon Nanotubes on Carbon Toray Paper for Bio-Fuel Cell Applications

2007 ◽  
Author(s):  
Bhupesh Chandra ◽  
Joshua T. Kace ◽  
Yuhao Sun ◽  
S. C. Barton ◽  
James Hone
Keyword(s):  
Carbon Nanotubes ◽  
Fuel Cell ◽  
Surface Area ◽  
High Surface ◽  
High Surface Area ◽  
Multiwall Carbon Nanotubes ◽  
Volume Ratio ◽  
Carbon Paper ◽  
Heating Process ◽  
Scale Production

In recent years carbon nanotubes have emerged as excellent materials for applications in which high surface area is required e.g. gas sensing, hydrogen storage, solar cells etc. Ultra-high surface to volume ratio is also a desirable property in the applications requiring enhanced catalytic activity where these high surface area materials can act as catalyst supports. One of the fastest developing areas needing such materials is fuel-cell. Here we investigate the process through which carbon nanotubes can be manufactured specifically to be used to increase the surface area of a carbon paper (Toray™). This carbon support is used in bio-catalytic fuel cell as an electrode to support enzyme which catalyzes the redox reaction. Deposition of nanotubes on these carbon fibers can result in great enhancement in the overall surface area to support the enzyme, which increases the reaction rate inside the fuel cell. The present paper describes a method to achieve ultra-thick growth of multiwall carbon nanotubes (MWNT) on a carbon Toray™ paper using a joule heating process and gas-phase catalyst. Using this method, we are able to achieve rapid, high-density, and uniform MWNT growth. This method is also potentially scalable toward larger-scale production.

scholarly journals Nanoporous Gold Electrodes and Their Applications in Analytical Chemistry

2013 ◽  
Vol 2013 ◽  
pp. 1-21 ◽  
Author(s):  
Maryanne M. Collinson
Keyword(s):  
Analytical Chemistry ◽  
Surface Area ◽  
Chemical Sensors ◽  
High Surface ◽  
High Surface Area ◽  
Pore Network ◽  
Nanoporous Gold ◽  
Dna Sensors ◽  
Porous Framework ◽  
Surface Areas

Nanoporous gold prepared by dealloying Au:Ag alloys has recently become an attractive material in the field of analytical chemistry. This conductive material has an open, 3D porous framework consisting of nanosized pores and ligaments with surface areas that are 10s to 100s of times larger than planar gold of an equivalent geometric area. The high surface area coupled with an open pore network makes nanoporous gold an ideal support for the development of chemical sensors. Important attributes include conductivity, high surface area, ease of preparation and modification, tunable pore size, and a bicontinuous open pore network. In this paper, the fabrication, characterization, and applications of nanoporous gold in chemical sensing are reviewed specifically as they relate to the development of immunosensors, enzyme-based biosensors, DNA sensors, Raman sensors, and small molecule sensors.

scholarly journals Potentiometric Biosensing of Ascorbic Acid, Uric Acid, and Cysteine in Microliter Volumes Using Miniaturized Nanoporous Gold Electrodes

Biosensors ◽  
2020 ◽  
Vol 11 (1) ◽  
pp. 10
Author(s):  
Christopher J. Freeman ◽  
Borkat Ullah ◽  
Md. Shafiul Islam ◽  
Maryanne M. Collinson
Keyword(s):  
Ascorbic Acid ◽  
Uric Acid ◽  
Surface Area ◽  
High Surface ◽  
High Surface Area ◽  
Nanoporous Gold ◽  
Redox Potentials ◽  
Biologically Relevant ◽  
Redox Sensing ◽  
Redox Molecules

Potentiometric redox sensing is a relatively inexpensive and passive approach to evaluate the overall redox state of complex biological and environmental solutions. The ability to make such measurements in ultra-small volumes using high surface area, nanoporous electrodes is of particular importance as such electrodes can improve the rates of electron transfer and reduce the effects of biofouling on the electrochemical signal. This work focuses on the fabrication of miniaturized nanoporous gold (NPG) electrodes with a high surface area and a small footprint for the potentiometric redox sensing of three biologically relevant redox molecules (ascorbic acid, uric acid, and cysteine) in microliter volumes. The NPG electrodes were inexpensively made by attaching a nanoporous gold leaf prepared by dealloying 12K gold in nitric acid to a modified glass capillary (1.5 mm id) and establishing an electrode connection with copper tape. The surface area of the electrodes was ~1.5 cm2, providing a roughness factor of ~16 relative to the geometric area of 0.09 cm2. Scanning electron microscopy confirmed the nanoporous framework. A linear dependence between the open-circuit potential (OCP) and the logarithm of concentration (e.g., Nernstian-like behavior) was obtained for all three redox molecules in 100 μL buffered solutions. As a first step towards understanding a real system, the response associated with changing the concentration of one redox species in the presence of the other two was examined. These results show that at NPG, the redox potential of a solution containing biologically relevant concentrations of ascorbic acid, uric acid, and cysteine is strongly influenced by ascorbic acid. Such information is important for the measurement of redox potentials in complex biological solutions.

Tuning Drug Release Profile from Nanoporous Gold Thin Films

2013 ◽  
Vol 1569 ◽  
pp. 259-263
Author(s):  
Ozge Kurtulus ◽  
Erkin Seker
Keyword(s):  
High Surface ◽  
High Surface Area ◽  
Volume Ratio ◽  
Controlled Drug Delivery ◽  
Release Profile ◽  
Nanoporous Gold ◽  
Pore Morphology ◽  
Drug Release Profile ◽  
Promising Candidate ◽  
Microfabrication Techniques

ABSTRACTNanoporous gold (np-Au) with its high surface area to volume ratio, tunable pore morphology, ease of surface modification with well-studied thiol chemistry, as well as integration with conventional microfabrication techniques is a promising candidate for controlled drug delivery studies. While it has been demonstrated that np-Au can retain and release drugs, release mechanisms and governing parameters are unclear. This paper reports on the effect of film thickness and morphology on the molecular release from np-Au films.

Design and Characterization of Micropost-Filled Reactor to Minimize Pressure Drop While Maximizing Surface-Area-to-Volume-Ratio

2006 ◽  
Author(s):  
J. Yeom ◽  
J.-H. Han ◽  
B. Bae ◽  
M. A. Shannon ◽  
R. I. Masel
Keyword(s):  
Pressure Drop ◽  
Surface Area ◽  
Figure Of Merit ◽  
High Surface ◽  
High Surface Area ◽  
Volume Ratio ◽  
Knudsen Flow ◽  
Total Analysis System ◽  
Dimensionless Figure Of Merit ◽  
Analysis System

Micropost-filled reactors are commonly found in many micro total analysis system applications because of their high surface area for the surrounding volume. Design rules for micropost-filled reactors are presented here to optimize the performance of the micro-preconcentrator, which is a component of a micro gas chromatography system. The dimensionless figure of merit is proposed to be used to minimize the pressure drop while maximizing the surface-area-to-volume-ratio for a given overall channel geometry of the micropost-filled preconcentrator. Two independent models from the literature are used to predict the pressure drop across the micropost-filled channels for low Reynolds number flows. The pressure drop can be expressed solely as a function of a design parameter, β = a/s, a ratio of a radius of each post and a half-spacing between two adjacent posts. Pressure drop measurements are performed to experimentally corroborate the pressure drop model and the optimization using the dimensionless figure of merit. As the number of microposts; for a given β increases in a given channel size, a greater surface-area-to-volume-ratio will occur for a fixed pressure drop. Therefore, increasing the arrays of posts with smaller diameters and spacing will optimize the microreactor for higher surface area for a given flow resistance, at least until Knudsen flow begins to dominate.

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