Pristine and oxidised Ag-nanoparticles on free-standing graphene as explored by X-ray photoelectron and Auger spectroscopy

2020 ◽  
Vol 693 ◽  
pp. 121533 ◽  
Author(s):  
M. Al-Hada ◽  
L. Gregoratti ◽  
M. Amati ◽  
M. Neeb
Keyword(s):  
Ag Nanoparticles ◽  
Auger Spectroscopy ◽  
Free Standing ◽  
X Ray

scholarly journals The Synergistic Effects of Alloying on the Performance and Stability of Co3Mo and Co7Mo6 for the Electrocatalytic Hydrogen Evolution Reaction

Hydrogen ◽  
2020 ◽  
Vol 1 (1) ◽  
pp. 11-21
Author(s):  
Youyi Sun ◽  
Alexey Y. Ganin
Keyword(s):  
Hydrogen Evolution ◽  
Synergistic Effects ◽  
Alkaline Media ◽  
Price Of Stability ◽  
X Ray Diffraction ◽  
Free Standing ◽  
X Ray ◽  
Current Decay ◽  
Earth Abundant ◽  
Current Densities

Metal alloys have become a ubiquitous choice as catalysts for electrochemical hydrogen evolution in alkaline media. However, scarce and expensive Pt remains the key electrocatalyst in acidic electrolytes, making the search for earth-abundant and cheaper alternatives important. Herein, we present a facile and efficient synthetic route towards polycrystalline Co3Mo and Co7Mo6 alloys. The single-phased nature of the alloys is confirmed by X-ray diffraction and electron microscopy. When electrochemically tested, they achieve competitively low overpotentials of 115 mV (Co3Mo) and 160 mV (Co7Mo6) at 10 mA cm−2 in 0.5 M H2SO4, and 120 mV (Co3Mo) and 160 mV (Co7Mo6) at 10 mA cm−2 in 1 M KOH. Both alloys outperform Co and Mo metals, which showed significantly higher overpotentials and lower current densities when tested under identical conditions, confirming the synergistic effect of the alloying. However, the low overpotential in Co3Mo comes at the price of stability. It rapidly becomes inactive when tested under applied potential bias. On the other hand, Co7Mo6 retains the current density over time without evidence of current decay. The findings demonstrate that even in free-standing form and without nanostructuring, polycrystalline bimetallic electrocatalysts could challenge the dominance of Pt in acidic media if ways for improving their stability were found.

Studies of the Coefficient of Thermal Expansion of Low-k ILD Materials by X-Ray Reflectivity

2006 ◽  
Vol 914 ◽  
Author(s):  
George Andrew Antonelli ◽  
Tran M. Phung ◽  
Clay D. Mortensen ◽  
David Johnson ◽  
Michael D. Goodner ◽  
...  
Keyword(s):  
Thin Films ◽  
Thermal Expansion ◽  
Coefficient Of Thermal Expansion ◽  
Chemical Vapor ◽  
Dielectric Materials ◽  
Free Standing ◽  
Dielectric Thin Films ◽  
X Ray ◽  
Chemical Vapor Deposited ◽  
Low K

AbstractThe electrical and mechanical properties of low-k dielectric materials have received a great deal of attention in recent years; however, measurements of thermal properties such as the coefficient of thermal expansion remain minimal. This absence of data is due in part to the limited number of experimental techniques capable of measuring this parameter. Even when data does exist, it has generally not been collected on samples of a thickness relevant to current and future integrated processes. We present a procedure for using x-ray reflectivity to measure the coefficient of thermal expansion of sub-micron dielectric thin films. In particular, we elucidate the thin film mechanics required to extract this parameter for a supported film as opposed to a free-standing film. Results of measurements for a series of plasma-enhanced chemical vapor deposited and spin-on low-k dielectric thin films will be provided and compared.

Grazing incidence small angle x-ray scattering from free-standing nanostructures

1999 ◽  
Vol 86 (12) ◽  
pp. 6763-6769 ◽  
Author(s):  
Markus Rauscher ◽  
Rogerio Paniago ◽  
Hartmut Metzger ◽  
Zoltan Kovats ◽  
Jan Domke ◽  
...  
Keyword(s):  
Small Angle ◽  
Grazing Incidence ◽  
Free Standing ◽  
X Ray ◽  
X Ray Scattering ◽  
Ray Scattering

Immobilized Covalent Triazine Frameworks Films as Effective Photocatalysts for Hydrogen Evolution Reaction

2021 ◽  
Author(s):  
Xunliang Hu ◽  
Irshad Hussain ◽  
Bien Tan
Keyword(s):  
Hydrogen Evolution ◽  
Water Splitting ◽  
Crystalline Structure ◽  
Large Scale ◽  
Interfacial Polymerization ◽  
Point Of View ◽  
Lateral Size ◽  
Free Standing ◽  
X Ray ◽  
Synthetic Approaches

Abstract Covalent triazine frameworks (CTFs) have recently been demonstrated as promising materials for photocatalytic water splitting and are usually used in the form of suspended powder. From a practical point of view, immobilized CTFs materials are more suitable for large-scale water splitting applications, owing to their convenient separation and recycling potential. However, existing synthetic approaches mainly result in insoluble and unprocessable powders, which makes their future device application still a huge challenge. Herein, we report an aliphatic amine-assisted interfacial polymerization method to obtain free-standing, crystalline CTFs film with excellent photoelectric performance. The lateral size of the film was up to 250 cm2, the average thickness can be regulated from 30-500 nm. The crystalline structure was confirmed by high-resolution transmission electron microscope (HR-TEM), powder X-ray diffraction (PXRD), and small-angle X-ray scattering (SAXS) analysis. Intrigued by the good light absorption, crystalline structure, and big lateral size of the film, it was immobilized on a glass support that exhibited good photocatalytic hydrogen evolution performance (5.4 mmol h-1 m-2) and was easy to recycle.

scholarly journals The effect of cobalt on morphology, structure, and ORR activity of electrospun carbon fibre mats in aqueous alkaline environments

2021 ◽  
Vol 12 ◽  
pp. 1173-1186
Author(s):  
Markus Gehring ◽  
Tobias Kutsch ◽  
Osmane Camara ◽  
Alexandre Merlen ◽  
Hermann Tempel ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Inductively Coupled Plasma ◽  
Elevated Temperatures ◽  
Current Collector ◽  
Alkaline Media ◽  
Emission Spectrometry ◽  
Free Standing ◽  
X Ray ◽  
Turbostratic Carbon ◽  
Current Densities

An innovative approach for the design of air electrodes for metal–air batteries are free-standing scaffolds made of electrospun polyacrylonitrile fibres. In this study, cobalt-decorated fibres are prepared, and the influence of carbonisation temperature on the resulting particle decoration, as well as on fibre structure and morphology is discussed. Scanning electron microscopy, Raman spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy, elemental analysis, and inductively coupled plasma optical emission spectrometry are used for characterisation. The modified fibre system is compared to a benchmark system without cobalt additives. Cobalt is known to catalyse the formation of graphite in carbonaceous materials at elevated temperatures. As a result of cobalt migration in the material the resulting overall morphology is that of turbostratic carbon. Nitrogen removal and nitrogen-type distribution are enhanced by the cobalt additives. At lower carbonisation temperatures cobalt is distributed over the surface of the fibres, whereas at high carbonisation temperatures it forms particles with diameters up to 300 nm. Free-standing, current-collector-free electrodes assembled from carbonised cobalt-decorated fibre mats display promising performance for the oxygen reduction reaction in aqueous alkaline media. High current densities at an overpotential of 100 mV and low overpotentials at current densities of 333 μA·cm−2 were found for all electrodes made from cobalt-decorated fibre mats carbonised at temperatures between 800 and 1000 °C.

scholarly journals Depth Profiling of the Chemical Composition of Free-Standing Carbon Dots Using X-ray Photoelectron Spectroscopy

2018 ◽  
Vol 122 (26) ◽  
pp. 14889-14897 ◽  
Author(s):  
Irene Papagiannouli ◽  
Minna Patanen ◽  
Valérie Blanchet ◽  
John D. Bozek ◽  
Manuel de Anda Villa ◽  
...  
Keyword(s):  
Chemical Composition ◽  
Photoelectron Spectroscopy ◽  
Carbon Dots ◽  
Depth Profiling ◽  
Free Standing ◽  
X Ray

Facile caffeine electrochemical detection via electrodeposited Ag nanoparticles with modifier polymers on carbon paste sensor at aqueous and micellar media

2020 ◽  
Vol 98 (4) ◽  
pp. 169-178 ◽  
Author(s):  
M. Shehata ◽  
S.M. Azab ◽  
A.M. Fekry
Keyword(s):  
Ag Nanoparticles ◽  
Surface Characterization ◽  
Electrochemical Impedance ◽  
Limit Of Detection ◽  
Electrochemical Techniques ◽  
Calibration Plot ◽  
Micellar Media ◽  
Carbon Paste ◽  
Detection Range ◽  
X Ray

The analysis and detection of caffeine (Caf) is very useful due to its widespread usage in several daily consumed beverages, food products, and pharmacological preparations with various physiological effects. The preparation of a newly electrodeposited Ag nanoparticles – cellulose acetate phthalate (CAP) – chitosan (Chit) modified carbon paste (ACCMCP) sensor for sensitive determination of Caf in 0.01 mol L−1 H3PO4 solution (pH 1.0–5.0) both in aqueous and micellar media (0.5 mmol L−1 SDS) was achieved. The interaction of Caf was monitored using electrochemical techniques such as cyclic voltammetry, differential pulse voltammetry, electrochemical impedance spectroscopy, and chronoamperometry, and surface characterization was carried out using X-ray diffraction, scanning electron microscope, and energy dispersive X-ray techniques. The linear detection range of Caf was between 4 and 500 μmol L−1 (r2 = 0.955) and the limit of detection obtained from the calibration plot was 0.252 μmol L−1. The sensor was applicable for detecting Caf in numerous real samples with recoveries from 98.03% to 101.60% without interference of any accompanying species, which ensures high method selectivity.

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