scholarly journals Preparation and Investigation of the Microtribological Properties of Graphene Oxide and Graphene Films via Electrostatic Layer-by-Layer Self-Assembly

2015 ◽  
Vol 2015 ◽  
pp. 1-8 ◽  
Author(s):  
Yongshou Hu ◽  
Haibing Ma ◽  
Wei Liu ◽  
Qianqian Lin ◽  
Bin Liu
Keyword(s):  
Graphene Oxide ◽  
Photoelectron Spectroscopy ◽  
Self Assembly ◽  
Adhesion Force ◽  
Strong Dependence ◽  
Layer By Layer ◽  
Crystal Silicon ◽  
X Ray ◽  
Graphene Films ◽  
Self Assembled

Graphene oxide (GO) films with controlled layers, deposited on single-crystal silicon substrates, were prepared by electrostatic self-assembly of negatively charged GO sheets. Afterward, graphene films were prepared by liquid-phase reduction of as-prepared GO films using hydrazine hydrate. The microstructures and microtribological properties of the samples were studied using X-ray photoelectron spectroscopy, Raman spectroscopy, X-ray diffraction, UV-visabsorption spectroscopy, water contact angle measurement, and atomic force microscopy. It is found that, whether GO films or graphene films, the adhesion force and the coefficients of friction both show strong dependence on the number of self-assembled layers, which both allow a downward trend as the number of self-assembled layers increases due to the interlayer sliding and the puckering effect when the tip slipped across the top surface of the films. Moreover, in comparison with the GO films with the same self-assembled layers, the graphene films possess lower adhesion force and coefficient of friction attributed to the difference of surface functional groups.

Preparation of Poly(diallydimethyl ammonium chloride) (PDDA)/Au Nanocomposite Film by In Situ Electrochemical Reduction and its Electrocatalytic Properties

2010 ◽  
Vol 123-125 ◽  
pp. 189-192
Author(s):  
Hong Wei Shi ◽  
Li Zhang ◽  
Cong Wang ◽  
Ke Ying Zhang
Keyword(s):  
Electrochemical Reduction ◽  
Ammonium Chloride ◽  
Photoelectron Spectroscopy ◽  
Self Assembly ◽  
Composite Films ◽  
Nanocomposite Films ◽  
Layer By Layer ◽  
X Ray ◽  
Assembly Technique

Nanocomposite films containing Au nanoparticles were fabricated by alternating adsorption of poly(diallydimethyl ammonium chloride) (PDDA) and HAuCl4 using layer-by-layer self-assembly technique and subsequent in situ electrochemical reduction of the AuCl4- ions. The composition and properties of the composite films were characterized by ultraviolet-visible spectroscopy (UV-vis), X-ray photoelectron spectroscopy (XPS), and cyclic voltammetry (CV).The UV-vis characteristic absorbances of PDDA and Au increase almost linearly with the number of bilayers, which suggests a progressive deposition with almost an equal amount of the PDDA and Au in each cycle. X-ray photoelectron spectroscopy further confirms the presence of the main components (such as PDDA and Au) of the nanocomposite films. Furthermore, the nanocomposite films also exhibit good electrocatalytic activity for the oxidation of ascorbic acid (AA), which may be used in electrochemical biosensors.

Fire retardancy of graphene oxide/wood composite (GOW) prepared by a vacuum-pulse dipping technique

Holzforschung ◽  
2018 ◽  
Vol 72 (5) ◽  
pp. 375-378 ◽  
Author(s):  
Xiaoshuai Han ◽  
Qinqin Zhang ◽  
Yihui Yin ◽  
Junwen Pu
Keyword(s):  
Graphene Oxide ◽  
Self Assembly ◽  
Degree Of Crystallinity ◽  
Multilayer Graphene ◽  
Layer By Layer ◽  
Fire Retardancy ◽  
X Ray Diffraction ◽  
X Ray ◽  
Natural Wood ◽  
Thermal Stability Of

AbstractGraphene oxide/wood (GOW) composite was fabricated by a vacuum-pulse dipping technique, and the resulting composites were characterized by scanning electron microscope (SEM), Raman spectroscopy and thermogravimetric analysis (TGA). As demonstrated, the wood matrix became filled by the dense multilayer graphene oxide (GO) membrane structure, which was formed by the layer-by-layer self-assembly of GO nano-sheets. X-ray diffraction (XRD) revealed that the amorphous GO decreased the composite’s relative degree of crystallinity. Additionally, the filled GO generated improvement in the thermal stability of GOW composites in comparison with that of the natural wood (NW).

Self-Assembly of Large Scale CdS/TiO2 Film Photocatalyst

2012 ◽  
Vol 512-515 ◽  
pp. 1692-1698 ◽  
Author(s):  
Chun Xiang Li ◽  
Zhao Hua Jiang ◽  
Zhong Ping Yao
Keyword(s):  
Photoelectron Spectroscopy ◽  
Self Assembly ◽  
Large Scale ◽  
Crystal Size ◽  
Composite Films ◽  
Atomic Ratio ◽  
Layer By Layer ◽  
Spectroscopy Analysis ◽  
X Ray ◽  
Layer Method

CdS/TiO2 composite films with different Cd:Ti atomic ratio were prepared by a new straightforward particulate layer-by-layer method. Titanium dihydroxide and thiourea were used as precursors. Raman and X-ray photoelectron spectroscopy analysis for the composite films revealed that the TiO2 formed from titanium precursor retarded the crystal growth of CdS. Luminescence and UV–vis absorption spectra investigation showed that emission and absorption band of CdS/TiO2 blue shifted as crystal size of CdS decreased. Furthermore, hydrogen formation curves revealed that hydroxyl of CdS/TiO2 films plays an important role in water splitting reaction under both UV and visible light irradiations.

Ultrathin Ruthenium(II) Complex–H4SiW12O40 Multilayer Film

2008 ◽  
Vol 8 (3) ◽  
pp. 1248-1253 ◽  
Author(s):  
Yu-Qi Zhang ◽  
Li-Hua Gao ◽  
Ke-Zhi Wang ◽  
Hong-Jun Gao ◽  
Ye-Liang Wang
Keyword(s):  
Atomic Force Microscopy ◽  
Cyclic Voltammetry ◽  
Photoelectron Spectroscopy ◽  
Self Assembly ◽  
Multilayer Film ◽  
Multilayer Films ◽  
Layer By Layer ◽  
X Ray ◽  
Force Microscopy ◽  
Atomic Force

A dipolar Ru(II) complex, [(bpy)2Ru(bpbh)Ru(bpy)2](ClO4)4 {where bpbh = 1,6-bis-[2-(2-pyridyl) benzimidazoyl]hexane, bpy = 2,2′-bipyridine}, was synthesized and characterized. A multilayer film of at least 18 layers was successfully prepared by alternating adsorption of H4SiW12O40 and [Ru2(bpy)4(bpbh)](ClO4)4 by electrostatic layer-by-layer self-assembly. The multilayer films were studied by ultraviolet-visible and X-ray photoelectron spectroscopy, atomic force microscopy, and cyclic voltammetry.

New Synthetic Approaches to Self-Assembled Chromophoric Multilayers as Second-Order Nonlinear Optical Materials

1995 ◽  
Vol 392 ◽  
Author(s):  
Wenbin Lin ◽  
Tobin J. Marks ◽  
Shlomo Yitzchaik ◽  
Weiping Lin ◽  
George K. Wong
Keyword(s):  
Photoelectron Spectroscopy ◽  
Self Assembly ◽  
Nonlinear Optical ◽  
Second Harmonic ◽  
Second Order ◽  
Nonlinear Optical Susceptibility ◽  
X Ray ◽  
Structural Regularity ◽  
Assembly Technology ◽  
Self Assembled

AbstractThis contribution describes the synthesis and properties of NLO-active self-assembled chromophoric multilayers. The stilbazolium self-assembled multilayers were prepared by new topotactic approaches based on siloxane self-assembly technology. X-ray photoelectron spectroscopy (XPS), advancing aqueous contact angle (θa) measurements, transmission optical spectroscopy, polarized second harmonic generation (SHG), and specular X-ray rellectivity (XRR) show that the resulting self-assembled chromophoric superlattices have very high structural regularity and very large second-order nonlinear optical susceptibility.

Investigation of two-component mixed self-assembled monolayers on gold

2001 ◽  
Vol 79 (3) ◽  
pp. 328-336
Author(s):  
Zhen Wang ◽  
Yan-Li Shi ◽  
Hu-Lin Li
Keyword(s):  
Photoelectron Spectroscopy ◽  
Self Assembly ◽  
Electrochemical Impedance ◽  
Impedance Analysis ◽  
Self Assembled Monolayers ◽  
X Ray ◽  
Molar Ratios ◽  
Two Component ◽  
Assembled Monolayers ◽  
Self Assembled

Two-component mixed self-assembled monolayers (SAMs) composed of 2-mercapto-5-methyl-1,3,4-oxadiazole (MMO) and 1-dodecanethiol (C12SH) in various molar percentages were prepared on gold surfaces by self-assembly. X-ray photoelectron spectroscopy (XPS) and wettability results gave evidence that the coverage of MMO was controlled by the composition of MMO in the assembling solution. The monolayer coverage and apparent rate constant of the redox active probes in solution of different molar ratios of mixed SAMs could be calculated using impedance measurements. The cyclic voltammetry reveals that the probes are selectively passed through the mixed SAMs depending upon their properties.Key words: self-assembled monolayers (SAMs), X-ray photoelectron spectroscopy (XPS), electrochemistry, electrochemical impedance analysis.

scholarly journals X-ray Photoelectron Spectroscopy Analysis of Chitosan–Graphene Oxide-Based Composite Thin Films for Potential Optical Sensing Applications

Polymers ◽  
2021 ◽  
Vol 13 (3) ◽  
pp. 478
Author(s):  
Wan Mohd Ebtisyam Mustaqim Mohd Daniyal ◽  
Yap Wing Fen ◽  
Silvan Saleviter ◽  
Narong Chanlek ◽  
Hideki Nakajima ◽  
...  
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Graphene Oxide ◽  
Photoelectron Spectroscopy ◽  
Functional Group ◽  
Optical Sensing ◽  
Composite Thin Films ◽  
Cobalt Ions ◽  
X Ray ◽  
Sensing Applications

In this study, X-ray photoelectron spectroscopy (XPS) was used to study chitosan–graphene oxide (chitosan–GO) incorporated with 4-(2-pyridylazo)resorcinol (PAR) and cadmium sulfide quantum dot (CdS QD) composite thin films for the potential optical sensing of cobalt ions (Co2+). From the XPS results, it was confirmed that carbon, oxygen, and nitrogen elements existed on the PAR–chitosan–GO thin film, while for CdS QD–chitosan–GO, the existence of carbon, oxygen, cadmium, nitrogen, and sulfur were confirmed. Further deconvolution of each element using the Gaussian–Lorentzian curve fitting program revealed the sub-peak component of each element and hence the corresponding functional group was identified. Next, investigation using surface plasmon resonance (SPR) optical sensor proved that both chitosan–GO-based thin films were able to detect Co2+ as low as 0.01 ppm for both composite thin films, while the PAR had the higher binding affinity. The interaction of the Co2+ with the thin films was characterized again using XPS to confirm the functional group involved during the reaction. The XPS results proved that primary amino in the PAR–chitosan–GO thin film contributed more important role for the reaction with Co2+, as in agreement with the SPR results.

scholarly journals Improvement of the thermal stability of dendritic silver-coated copper microparticles by surface modification based on molecular self-assembly

2021 ◽  
Vol 8 (1) ◽  
Author(s):  
Tae Hyeong Kim ◽  
Hyeji Kim ◽  
Hyo Jun Jang ◽  
Nara Lee ◽  
Kwang Hyun Nam ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Photoelectron Spectroscopy ◽  
Self Assembly ◽  
Electrically Conductive ◽  
X Ray ◽  
Alkyl Chains ◽  
Conductive Film ◽  
Initial Resistance ◽  
Thermal Stability Of ◽  
Scanning Electron

AbstractIn the study reported herein, silver-coated copper (Ag/Cu) powder was modified with alkanethiols featuring alkyl chains of different lengths, namely butyl, octyl, and dodecyl, to improve its thermal stability. The modification of the Ag/Cu powders with adsorbed alkanethiols was confirmed by scanning electron microscopy with energy dispersive spectroscopy, X-ray photoelectron spectroscopy, and thermogravimetric analysis. Each powder was combined with an epoxy resin to prepare an electrically conductive film. The results confirmed that the thermal stability of the films containing alkanethiol-modified Ag/Cu powders is superior to that of the film containing untreated Ag/Cu powder. The longer the alkyl group in the alkanethiol-modified Ag/Cu powder, the higher the initial resistance of the corresponding electrically conductive film and the lower the increase in resistance induced by heat treatment.

scholarly journals Direct Patterning and Spontaneous Self-Assembly of Graphene Oxide via Electrohydrodynamic Jet Printing for Energy Storage and Sensing

Micromachines ◽  
2019 ◽  
Vol 11 (1) ◽  
pp. 13 ◽  
Author(s):  
Bin Zhang ◽  
Jaehyun Lee ◽  
Mincheol Kim ◽  
Naeeung Lee ◽  
Hyungdong Lee ◽  
...  
Keyword(s):  
Graphene Oxide ◽  
Energy Storage ◽  
Self Assembly ◽  
High Performance ◽  
Three Dimensional ◽  
Chemical Properties ◽  
Layer By Layer ◽  
Energy Storage Devices ◽  
Laminar Structure ◽  
Jet Printing

The macroscopic assembly of two-dimensional materials into a laminar structure has received considerable attention because it improves both the mechanical and chemical properties of the original materials. However, conventional manufacturing methods have certain limitations in that they require a high temperature process, use toxic solvents, and are considerably time consuming. Here, we present a new system for the self-assembly of layer-by-layer (LBL) graphene oxide (GO) via an electrohydrodynamic (EHD) jet printing technique. During printing, the orientation of GO flakes can be controlled by the velocity distribution of liquid jet and electric field-induced alignment spontaneously. Closely-packed GO patterns with an ordered laminar structure can be rapidly realized using an interfacial assembly process on the substrates. The surface roughness and electrical conductivity of the LBL structure were significantly improved compared with conventional dispensing methods. We further applied this technique to fabricate a reduced graphene oxide (r-GO)-based supercapacitor and a three-dimensional (3D) metallic grid hybrid ammonia sensor. We present the EHD-assisted assembly of laminar r-GO structures as a new platform for preparing high-performance energy storage devices and sensors.

Interaction of nitric oxide with Ru(II) complexes of deuteroporphyrindimethylester derivatives

2009 ◽  
Vol 13 (01) ◽  
pp. 35-40 ◽  
Author(s):  
Rudy Martin ◽  
Roberto Cao ◽  
Ana M. Esteva ◽  
Franz-Peter Montforts
Keyword(s):  
Nitric Oxide ◽  
Photoelectron Spectroscopy ◽  
Gold Electrode ◽  
Charge Transfer Band ◽  
Bathochromic Shift ◽  
Considerable Change ◽  
Cathodic Peak ◽  
X Ray ◽  
Polycrystalline Gold ◽  
Self Assembled

A new ruthenium(II) porphyrin disulphide derivative, [ Ru ( Pds )( CO )], was obtained from ruthenium(II)(carbonyl)deuteroporphyrin(IX), [ Ru ( DPdc )( CO )] and cystamine. The interaction of this complex with nitric oxide was studied spectrophotometrically and a bathochromic shift of the charge transfer band and considerable change in the α and β bands of the complex were observed. According to the IR spectrum, the product of this interaction is [ Ru ( DmDP )( NO +)( NO 2-)]. [ Ru ( Pds )( CO )] was then self-assembled on polycrystalline gold and characterized by X-ray photoelectron spectroscopy. [ Ru ( Pds )( CO )] was also self-assembled on gold electrode beads and its interaction with nitric oxide in aqueous solution was studied by cyclic voltammetry. A shift in the ruthenium redox process and a new irreversible cathodic peak at -0.59 V were observed, both indicating coordination of NO .

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