scholarly journals Immobilized covalent triazine frameworks films as effective photocatalysts for hydrogen evolution reaction

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Xunliang Hu ◽  
Zhen Zhan ◽  
Jianqiao Zhang ◽  
Irshad Hussain ◽  
Bien Tan
Keyword(s):  
Hydrogen Evolution ◽  
Water Splitting ◽  
Large Scale ◽  
Interfacial Polymerization ◽  
Lateral Size ◽  
Free Standing ◽  
X Ray ◽  
X Ray Scattering ◽  
Formidable Challenge ◽  
Ray Scattering

AbstractCovalent triazine frameworks 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, owing to their convenient separation and recycling potential. However, existing synthetic approaches mainly result in insoluble and unprocessable powders, which make their future device application a formidable challenge. Herein, we report an aliphatic amine-assisted interfacial polymerization method to obtain free-standing, semicrystalline CTFs film with excellent photoelectric performance. The lateral size of the film was up to 250 cm2, and average thickness can be tuned from 30 to 500 nm. The semicrystalline structure was confirmed by high-resolution transmission electron microscope, powder X-ray diffraction, grazing-incidence wide-angle X-ray scattering, and small-angle X-ray scattering analysis. Intrigued by the good light absorption, crystalline structure, and large lateral size of the film, the film immobilized on a glass support exhibited good photocatalytic hydrogen evolution performance (5.4 mmol h−1 m−2) with the presence of co-catalysts i.e., Pt nanoparticles and was easy to recycle.

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.

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

The nature of the scattering tail in Cu–Ni–Fe and Invar alloys investigated by anomalous small-angle X-ray scattering

1991 ◽  
Vol 24 (6) ◽  
pp. 1027-1034 ◽  
Author(s):  
J. P. Simon ◽  
O. Lyon
Keyword(s):  
Small Angle ◽  
Large Scale ◽  
Concentration Fluctuations ◽  
X Ray ◽  
Invar Alloys ◽  
X Ray Scattering ◽  
Angle Measurements ◽  
Two Systems ◽  
Fe Alloys ◽  
Ray Scattering

A large rapidly decreasing intensity called the `scattering tail' is generally observed at the smallest recorded angles during small-angle measurements of metallic alloys. Since this tail was interpreted as caused by a bimodal phase separation in Cu–Ni–Fe alloys and by long-wavelength concentration fluctuations in Invar alloys, these two systems were re-examined with anomalous X-ray scattering. The variation of the alloying atomic contrasts allows a discrimination between the different types of particles or defects. In neither of the two systems can the tails be interpreted as caused by large-scale concentration fluctuations. In Cu–Ni–Fe alloys, the tail is due to some kind of superficial defect (surface roughness etc.). In Invar alloys, the tail is probably due to residual impurity particles.

scholarly journals Resonant x-ray scattering at the Se edge in liquid crystal free-standing films and devices

2000 ◽  
Vol 76 (14) ◽  
pp. 1863-1865 ◽  
Author(s):  
L. S. Matkin ◽  
H. F. Gleeson ◽  
P. Mach ◽  
C. C. Huang ◽  
R. Pindak ◽  
...  
Keyword(s):  
Liquid Crystal ◽  
Free Standing ◽  
X Ray ◽  
X Ray Scattering ◽  
Ray Scattering

Small-angle X-ray scattering by PVP–water mixtures

2001 ◽  
Vol 34 (1) ◽  
pp. 62-64 ◽  
Author(s):  
Jan van der Elsken ◽  
Wim Bras ◽  
Jan Michielsen
Keyword(s):  
Small Angle ◽  
Large Scale ◽  
Columnar Structure ◽  
Water Mixture ◽  
X Ray ◽  
Large Scale Structures ◽  
X Ray Scattering ◽  
Angle Scattering ◽  
Hexagonal Columnar ◽  
Ray Scattering

Small-angle X-ray scattering experiments reveal the formation of large-scale structures when a 60 wt% poly(vinylpyrrolidone) (PVP)–water mixture is cooled to 260 K. The formation of these structures leads to an enhancement of continuous small-angle scattering with decreasing temperature. This is accompanied by the appearance of sharp Bragg peaks that have a very short lifetime. The scattering angles of these peaks are in accordance with a hexagonal columnar structure. It appears that such structures occasionally live long enough to undergo rotational Brownian motion.

scholarly journals A new small-angle X-ray scattering model for polymer spherulites with a limited lateral size of the lamellar crystals

IUCrJ ◽  
2019 ◽  
Vol 6 (5) ◽  
pp. 968-983 ◽  
Author(s):  
Xiang-Yang Li ◽  
Jian-Jun Ding ◽  
Yan-Ping Liu ◽  
Xing-You Tian
Keyword(s):  
Small Angle ◽  
Evanescent Wave ◽  
Polymer System ◽  
Destructive Interference ◽  
Lateral Size ◽  
Lamellar System ◽  
X Ray ◽  
X Ray Scattering ◽  
Lamellar Crystals ◽  
Ray Scattering

As is well known, polymers commonly form lamellar crystals, and these assemble further into lamellar stacks and spherulites during quiescent crystallization. Fifty years ago, Vonk and Kortleve constructed the classical small-angle X-ray scattering theory (SAXS) for a lamellar system, in which it was assumed that the lamellar stack had an infinite lateral size [Vonk & Kortleve (1967), Kolloid Z. Z. Polym. 220, 19–24]. Under this assumption, only crystal planes satisfying the Bragg condition can form strong scattering, and the scattering from the lamellar stack arises from the difference between the scattering intensities in the amorphous and crystalline layers, induced by the incident X-ray beam. This assumption is now deemed unreasonable. In a real polymer spherulite, the lamellar crystal commonly has dimensions of only a few hundred nanometres. At such a limited lateral size, lamellar stacks in a broad orientation have similar scattering, so interference between these lamellar stacks must be considered. Scattering from lamellar stacks parallel to the incident X-ray beam also needs to be considered when total reflection occurs. In this study, various scattering contributions from lamellar stacks in a spherulite are determined. It is found that, for a limited lateral size, the scattering induced by the incident X-ray beam is not the main origin of SAXS. It forms double peaks, which are not observed in real scattering because of destructive interference between the lamellar stacks. The scattering induced by the evanescent wave is the main origin. It can form a similar interference pattern to that observed in a real SAXS measurement: a Guinier region in the small-q range, a signal region in the intermediate-q range and a Porod region in the high-q range. It is estimated that, to avoid destructive interference, the lateral size needs to be greater than 11 µm, which cannot be satisfied in a real lamellar system. Therefore, SAXS in a real polymer system arises largely from the scattering induced by the evanescent wave. Evidence for the existence of the evanescent wave was identified in the scattering of isotactic polypropylene. This study corrects a long-term misunderstanding of SAXS in a polymer lamellar system.

scholarly journals Automated structural modeling in biological small-angle X-ray scattering

2014 ◽  
Vol 70 (a1) ◽  
pp. C404-C404
Author(s):  
Dmitry Svergun
Keyword(s):  
Data Processing ◽  
Small Angle ◽  
Large Scale ◽  
Structural Changes ◽  
Structural Parameters ◽  
Structural Models ◽  
Assessment Tools ◽  
X Ray ◽  
X Ray Scattering ◽  
Ray Scattering

Small-angle X-ray scattering (SAXS) experiences a renaissance in the studies of macromolecular solutions allowing one to study the structure of native particles and complexes and to rapidly analyze structural changes in response to variations in external conditions. New high brilliance sources and novel data analysis methods significantly enhanced resolution and reliability of structural models provided by the technique (Graewert & Svergun, 2013). Automation of the experiment, data processing and interpretation make solution SAXS a streamline tool for large scale structural studies in molecular biology. The recent developments will be presented including robotic sample changers, pipelines for data processing, computation of structural parameters and ab initio models, classification of the folding states of macromolecules. A prototype of an expert systems allowing for automated generation and assessment of structural models will be considered. A synergistic use of SAXS with the high resolution methods like crystallography and NMR, but also with complementary biophysical and biochemical techniques will be discussed. The problems of validation of SAXS-generated models, and the use of data quality assessment tools for the deposition of the models and experimental data will be discussed. Further perspectives of the hybrid applications of SAXS with other techniques in structural biology will be outlined.

Sign in / Sign up

Export Citation Format

Share Document