Surface Chemistry of Nanocrystalline Cerium Oxide

1994 ◽  
Vol 351 ◽  
Author(s):  
Andreas Tschöpe ◽  
J.Y. Ying ◽  
K. Amonlirdviman ◽  
M. L. Trudeau
Keyword(s):  
Surface Chemistry ◽  
Cerium Oxide ◽  
Photoelectron Spectroscopy ◽  
Synergistic Effects ◽  
Oxygen Deficiency ◽  
High Surface ◽  
Reaction Chamber ◽  
Surface Reactivity ◽  
Promoting Effect ◽  
Reduction And Oxidation

ABSTRACTNanocrystalline cerium oxide was synthesized by magnetron sputtering of a metallic target, followed by controlled post-oxidation. The resulting cerium oxide clusters were <10 nm in size, and highly non-stoichiometric in nature. The oxygen deficiency of such materials was associated with the unusual catalytic activity in oxidation and redox reactions. This paper compares the surface chemistry of nanocrystalline CeO2−x with stoichiometric CeO2. It further explores the promoting effect of Cu-doping on surface reduction and oxidation.The oxidation states of metal cations were examined with X-ray photoelectron spectroscopy after various oxidizing and reducing heat treatments in a connected reaction chamber. Isothermal pulsed reduction and oxidation of the samples were investigated by thermogravimetric analysis. Reduction properties of the different materials are discussed in terms of their microstructure, oxygen deficiency and chemical composition. These studies will help to understand the importance of bulk defects and synergistic effects in multicomponent and multiphase materials for high surface reactivity.

scholarly journals Defluorination of Polytetrafluoroethylene Surface by Hydrogen Plasma

Polymers ◽  
2020 ◽  
Vol 12 (12) ◽  
pp. 2855
Author(s):  
Alenka Vesel ◽  
Dane Lojen ◽  
Rok Zaplotnik ◽  
Gregor Primc ◽  
Miran Mozetič ◽  
...  
Keyword(s):  
Surface Chemistry ◽  
Photoelectron Spectroscopy ◽  
Treatment Time ◽  
Synergistic Effects ◽  
Surface Film ◽  
Hydrogen Plasma ◽  
Contact Angles ◽  
Hydrogen Atoms ◽  
Tof Sims ◽  
Discharge Parameters

Defluorination of polytetrafluoroethylene (PTFE) surface film is a suitable technique for tailoring its surface properties. The influence of discharge parameters on the surface chemistry was investigated systematically using radio-frequency inductively coupled H2 plasma sustained in the E- and H-modes at various powers, pressures and treatment times. The surface finish was probed by X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry (ToF-SIMS). The measurements of water contact angles (WCA) showed increased wettability of the pristine PTFE; however, they did not reveal remarkable modification in the surface chemistry of the samples treated at various discharge parameters. By contrast, the combination of XPS and ToF-SIMS, however, revealed important differences in the surface chemistry between the E- and H-modes. A well-expressed minimum in the fluorine to carbon ratio F/C as low as 0.2 was observed at the treatment time as short as 1 s when plasma was in the H-mode. More gradual surface chemistry was observed when plasma was in the E-mode, and the minimal achievable F/C ratio was about 0.6. The results were explained by the synergistic effects of hydrogen atoms and vacuum ultraviolet radiation.

Sorption of actinides onto nanodiamonds

2015 ◽  
Vol 103 (3) ◽  
Author(s):  
Yulia Buchatskaya ◽  
Anna Romanchuk ◽  
Ruslan Yakovlev ◽  
Andrei Shiryaev ◽  
Inna Kulakova ◽  
...  
Keyword(s):  
Surface Chemistry ◽  
Sorption Capacity ◽  
Photoelectron Spectroscopy ◽  
High Surface ◽  
High Surface Area ◽  
Sorption Properties ◽  
Closed Chamber ◽  
X Ray ◽  
Commercial Scale ◽  
Low Weight

AbstractDetonation nanodiamonds (ND) present a significant part of nanocarbons group, which could be produced on commercial scale by detonation of explosives in a closed chamber. Their unique properties of high surface area, low weight and radiation resistance make ND a prospective candidate for applications in sorption processes in radiochemistry. To study the influence of surface chemistry on sorption properties, apristine sample of ND was treated with acids and hydrogen. The surface chemistry of the samples was characterised by infrared spectroscopy, X-ray photoelectron spectroscopy and Boehm titration. The sorption properties of ND were tested fordifferent radionuclides. The sorption capacity of ND was shown to be higher than those of commonly used radionuclide sorbents like activated carbon and compariable to other members of nanocarbon group like graphene oxide and carbon nanotubes. The sorption properties were shown to be influenced by the presence of oxygen-containing groups on the surface of ND. This represents an opportunity to increase the sorption capacity of ND.

scholarly journals Effective Synthesis of Carbon Hybrid Materials Containing Oligothiophene Dyes

Materials ◽  
2019 ◽  
Vol 12 (20) ◽  
pp. 3354 ◽  
Author(s):  
Piotr Kamedulski ◽  
Piotr A. Gauden ◽  
Jerzy P. Lukaszewicz ◽  
Anna Ilnicka
Keyword(s):  
Confocal Microscopy ◽  
Surface Chemistry ◽  
Pore Structure ◽  
Hybrid Materials ◽  
Photoelectron Spectroscopy ◽  
High Surface ◽  
Dye Adsorption ◽  
Nitrogen Adsorption ◽  
Deposition Process ◽  
Elemental Content

This paper shows the first study of the synthesis of hybrid materials consisting of commercial Norit carbons and oligothiophenes. The study presents the influence of surface oxidation on dye deposition as well as changes of pore structure and surface chemistry. The hybrid materials were characterised using Raman spectroscopy, and scanning and transmission electron microscopy (SEM and HR-TEM, respectively). Confocal microscopy was employed to confirm the immobilization of oligomers on the surface of the carbons being investigated. Confocal microscopy measurements were additionally used to indicate whether dye molecules covered the entire surface of the selected commercial Norit samples. Specific surface area and pore structure parameters were determined by low-temperature nitrogen adsorption. Additionally, elemental content and surface chemistry were characterised by means of X-ray photoelectron spectroscopy (XPS) and combustion elemental analysis. Experimental results confirmed that oligothiophene dyes were adsorbed onto the internal part of the investigated pores of the carbon materials. The pores were assumed to have a slit-like shape, a set of 82 local adsorption isotherms was modelled for pores from 0.465 nm to 224 nm. Further, XPS data showed promising qualitative results regarding the surface characteristics and chemical composition of the hybrid materials obtained (sulphur content ranged from 1.40 to 1.45 at%). It was shown that the surface chemistry of activated carbon plays a key role in the dye deposition process. High surface heterogeneity after hydrothermal oxidation did not improve dye adsorption due to specific interactions between surface oxygen moieties and local electric charges in the oligothiophene molecules.

VAPOR-PHASE CHEMICAL FUNCTIONALIZATION OF HIGH POROSITY, NANOSTRUCTURED THIN FILMS

2007 ◽  
Vol 06 (02) ◽  
pp. 103-107 ◽  
Author(s):  
SHUFEN TSOI ◽  
ENRICO FOK ◽  
JONATHAN G. C. VEINOT ◽  
JEREMY C. SIT
Keyword(s):  
Thin Films ◽  
Surface Chemistry ◽  
Vapor Phase ◽  
Photoelectron Spectroscopy ◽  
High Surface ◽  
High Surface Area ◽  
High Porosity ◽  
Complete Control ◽  
Angle Measurements ◽  
Phase Surface

Trifluoropropyl-trichlorosilane reagents were used to tailor the surface chemistry of porous nano-structured thin films fabricated using glancing angle deposition (GLAD). GLAD produces high surface area films of isolated columnar structures and provides complete control over the film morphology. Here, the chemical tunability of these GLAD films was investigated using solution and vapor-phase surface functionalization methods. All films were characterized using scanning electron microscopy, X-ray photoelectron spectroscopy and advancing aqueous contact angle measurements. Our results indicate that the surface chemistry of the GLAD films was effectively changed after functionalization by either approaches. We also note that vapor-phase functionalization provides more consistent results and eliminates the need for organic solvents, making it an ideal method for tailoring the surface properties of GLAD films for specific applications.

Recent Advances in Application of Azobenzenes Grafted on Mesoporous Silica Nanoparticles in Controlled Drug Delivery Systems Using Light as External Stimulus

2020 ◽  
Vol 20 (11) ◽  
pp. 1001-1016
Author(s):  
Sandra Ramírez-Rave ◽  
María Josefa Bernad-Bernad ◽  
Jesús Gracia-Mora ◽  
Anatoly K. Yatsimirsky
Keyword(s):  
Drug Delivery ◽  
Mesoporous Silica ◽  
Silica Nanoparticles ◽  
Drug Delivery Systems ◽  
Mesoporous Silica Nanoparticles ◽  
High Surface ◽  
Delivery Systems ◽  
Surface Reactivity ◽  
External Stimulus ◽  
Recent Advances

Hybrid materials based on Mesoporous Silica Nanoparticles (MSN) have attracted plentiful attention due to the versatility of their chemistry, and the field of Drug Delivery Systems (DDS) is not an exception. MSN present desirable biocompatibility, high surface area values, and a well-studied surface reactivity for tailoring a vast diversity of chemical moieties. Particularly important for DDS applications is the use of external stimuli for drug release. In this context, light is an exceptional alternative due to its high degree of spatiotemporal precision and non-invasive character, and a large number of promising DDS based on photoswitchable properties of azobenzenes have been recently reported. This review covers the recent advances in design of DDS using light as an external stimulus mostly based on literature published within last years with an emphasis on usually overlooked underlying chemistry, photophysical properties, and supramolecular complexation of azobenzenes.

scholarly journals Non-Thermal Plasma-Modified Ru-Sn-Ti Catalyst for Chlorinated Volatile Organic Compound Degradation

Catalysts ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 1456
Author(s):  
Yujie Fu ◽  
You Zhang ◽  
Qi Xin ◽  
Zhong Zheng ◽  
Yu Zhang ◽  
...  
Keyword(s):  
Plasma Treatment ◽  
Photoelectron Spectroscopy ◽  
High Surface ◽  
High Surface Area ◽  
Surface Oxidation ◽  
Treatment Method ◽  
X Ray ◽  
Chlorinated Volatile Organic Compounds ◽  
Volatile Organic ◽  
Doped Titania

Chlorinated volatile organic compounds (CVOCs) are vital environmental concerns due to their low biodegradability and long-term persistence. Catalytic combustion technology is one of the more commonly used technologies for the treatment of CVOCs. Catalysts with high low-temperature activity, superior selectivity of non-toxic products, and resistance to chlorine poisoning are desirable. Here we adopted a plasma treatment method to synthesize a tin-doped titania loaded with ruthenium dioxide (RuO2) catalyst, possessing enhanced activity (T90%, the temperature at which 90% of dichloromethane (DCM) is decomposed, is 262 °C) compared to the catalyst prepared by the conventional calcination method. As revealed by transmission electron microscopy, X-ray diffraction, N2 adsorption, X-ray photoelectron spectroscopy, and hydrogen temperature-programmed reduction, the high surface area of the tin-doped titania catalyst and the enhanced dispersion and surface oxidation of RuO2 induced by plasma treatment were found to be the main factors determining excellent catalytic activities.

scholarly journals Probing the surface reactivity of nanocrystals by the catalytic degradation of organic dyes: the effect of size, surface chemistry and composition

2017 ◽  
Vol 5 (23) ◽  
pp. 11917-11929 ◽  
Author(s):  
Jordi Piella ◽  
Florind Merkoçi ◽  
Aziz Genç ◽  
Jordi Arbiol ◽  
Neus G. Bastús ◽  
...  
Keyword(s):  
Surface Chemistry ◽  
Surface Coating ◽  
Crystal Size ◽  
Organic Dyes ◽  
Catalytic Performance ◽  
Surface Reactivity ◽  
Catalytic Degradation ◽  
Comprehensive Study

We herein present a comprehensive study on how the catalytic performance and reusability of Au nanocrystals (NCs) are affected by systematic variations of crystal size, surface coating and composition.

scholarly journals Preparation and Characterization of Biocompatible Electrospun Nanofiber Scaffolds

2018 ◽  
Vol 62 (4) ◽  
Author(s):  
Edit Hirsch ◽  
Márió Nacsa ◽  
Ferenc Ender ◽  
Miklós Mohai ◽  
Zsombor K. Nagy ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
High Surface ◽  
High Surface Area ◽  
Volume Ratio ◽  
Surface Characteristic ◽  
Poly Lactic Acid ◽  
Nanofibrous Scaffolds ◽  
Plasma Surface Treatment ◽  
Nanoscale Fibers ◽  
Solution Electrospinning

Nanoscale fibers were prepared for the fabrication of scaffolds by using a strong electrostatic field on the polymer solution. Electrospinning is widely applied for production of drug delivery, tissue engineering, and regenerative medicine systems as well as biosensors and enzyme immobilization. Nanofibers, thanks to their high surface area to volume ratio, can also mimic the extracellular matrix, thus it has been recognized as a suitable technique for the fast fabrication of scaffolds. This article demonstrates the fabrication of several nanofibrous scaffolds from biopolymers such as polycaprolactone, poly(lactic acid), poly(lactide-co-glycolide), poly(lactide-co-caprolactone) and poly(hydroxybutyrate-co-hydroxy valerate). The characterization and comparison of the scaffolds were achieved based on the morphology and surface characteristic of the nanofibers. The samples showed hydrophobic characteristic, thus a plasma surface treatment was applied successfully to increase hydrophilicity and the effect of the treatment was evaluated based on the wettability and the change in elemental composition of the surface based on X-ray photoelectron spectroscopy.

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