Large Amount Of Oxygen-containing Groups Research Articles

Femtosecond laser texturing assisted cold plasma hydrophilization of polytetrafluoroethylene surface

Polytetrafluoroethylene (PTFE) is one of the most widely used engineering polymers, but PTFE-based bonding pairs are prone to failure due to its natural hydrophobicity induced weak interfacial bonding strength. Herein, we propose to improve the hydrophilicity of PTFE surface by femtosecond laser texturing assisted cold plasma modification. Specifically, PTFE surface is firstly textured by femtosecond laser ablation, and then modified by either direct cold plasma treatment or cold plasma induced graft polymerization of acrylic acid. The synergetic treatment roughens the PTFE surface on both micro and nano scales and introduces a large amount of oxygen-containing groups, making the treated surface hydrophilic (water contact angle < 30°). The hierarchically rough and hydrophilic PTFE surface favors its bonding with Cu by forming a mechanically interlocked and robust adhesive interface, and the maximum shearing strength and peeling strength of the bonding pairs were measured to be 2.75 MPa and 6.37 N/mm, respectively. The laser texturing assisted plasma modification enables durable surface hydrophilization and adhesive property improvement for PTFE compared with other previously reported methods, and thereby offers new insights into the fabrication of high-performance PTFE-based bonding components, as well as other functional units that require high-efficiency surface hydrophilization and robust bonding.

Accelerating proton conduction in proton exchange membranes with sandwich structure based on carbon nanotubes oxide

Carbon nanotubes (CNTs) with a high aspect ratio can theoretically realize the concept of channel-like proton transport clusters. In this research, carbon nanotubes oxide (OCNTs) with large amounts of oxygen-containing groups constituted successive proton conduction channels, deriving from the surface oxidation of CNTs. Proton exchange membranes (PEMs) with sandwich structure were constructed through a couple of polyvinyl chloride nanofbers (PNs) mats wrapping a thin OCNTs layer. In the prepared (PNs/OCNTs/PNs)es membrane, the outer polyvinyl chloride (PVC) nanofibers delayed the leakage of the inner OCNTs and enveloped phosphoric acid (PA) molecules. Furthermore, more PA molecules were combined by the oxygen-containing groups of hydroxyl, epoxy and carboxyl on the surface of OCNTs with intermolecular hydrogen bonds. For the (PNs/OCNTs/PNs)es/PA membrane, the good structure stability, high proton conductivity and reinforced mechanical property were derived from the compact structure, fast proton conduction and the formation of inorganic-organic composites. Specifically, the maximum proton conductivity was 4.46 × 10−2 S/cm at 160 °C, higher than 2.75 × 10−3 S/cm of the PVC/OCNTs/PA membrane. Notably, the tensile stress values reached 5.42 MPa of the (PNs/OCNTs/PNs)es membrane and 7.32 MPa of the (PNs/OCNTs/PNs)es/PA membrane. Even after a 350 h non-stop measurement at 120 °C, the (PNs/OCNTs/PNs)es/PA membrane could have the complete surface, albeit with tiny cracks on cross section. The proton conductivity could maintain the proton conductivity of 3.17 × 10−2 S/cm at 160 °C. The research revealed that OCNTs provided the channel-like ionic clusters for proton conduction and sandwich structure accelerated proton conduction in the OCNTs-based membranes.

Structural Defects of Graphene Oxidation Reduction and Its High-Efficiency Structural Reforming Technology

The Hummers’ method is used to prepare graphene oxide and graphene powder, and the obtained powder material contains a large amount of oxygen-containing groups. Due to the effect of strong oxidants, there are many defects on the graphene body. Although a large number of oxygen-containing groups are reduced by the reduction reaction, the defects of the graphene body are numerous, which has a great influence on the conductivity of graphene and also limits the high carrier transport capability and application of graphene itself. Using industrial means, the graphene powder is highly reduced, and the ultrathin graphene powder is obtained, the graphene powder has extremely low impurity content, and the defects are substantially completely reduced. Then, these lay the foundation for its application in the battery industry.

Flexible and conductive meta-aramid fiber paper with high thermal and chemical stability for electromagnetic interference shielding

How to function properly under extreme working conditions is a key challenge for flexible electronic devices because their performance is often susceptible to environmental conditions. Herein, we demonstrated the fabrication, evaluation, and application of a flexible and highly conductive meta-aramid fiber paper (MAFP) by combining oxygen plasma treatment and electroless silver plating. The plasma treatment etched the MAFP surface and introduced large amounts of oxygen-containing groups which led to the formation of continuous silver coating and high interface binding between MAFP and Ag nanoparticles. The results showed that the silver-coated MAFP had an electrical resistance as low as 0.152 Ω/sq and exhibited excellent temperature, mechanical and chemical stability. Finally, these properties of silver-coated MAFP were exploited for its use as electromagnetic interference (EMI) shielding. Experimental results revealed that the EMI shielding effectiveness (SE) of the silver-coated MAFP reached as high as 95.47 dB and a specific EMI SE of 530.38 dB·mm−1. These results have clearly demonstrated that MAFP can become highly electrically conductive after simple plasma treatment and silver coating while keeping its excellent thermal and chemical stability and therefore holds great promise for the development of new kinds of all-weather flexible electronic devices.

Cadmium adsorption behavior of porous and reduced graphene oxide and its potential for promoting cadmium migration during soil electrokinetic remediation

In this study, a porous reduced graphene oxide (PRGO) carbon nanomaterial was successfully obtained by activation of natural graphite with KOH at high temperature and was applied as an auxiliary electrode in soil electrokinetic remediation to investigate the promoting effect on Cd migration. We found that PRGO contained a large amount of oxygen-containing groups (hydroxyl and carboxyl groups) and exhibited high Cd2+ adsorption efficiency at pH values above 4, achieving a maximum adsorption capacity of 434.78 mg/g for Cd. In addition, PRGO could selectively adsorb Cd, Pb, Cu, and Zn but not K, Na, or Mg from soil solution. The electrokinetic remediation experiment showed that the PRGO auxiliary electrode promoted the migration of Cd and effectively controlled the increase in soil pH near the cathode, possibly due to ion exchange between the surface functional groups on the auxiliary electrode and Cd2+. In addition, the location of the PRGO auxiliary electrode strongly influenced the migration of Cd. For instance, the soil Cd concentration of treatment H-5 was 57.86% lower than that of H-0 at a distance of 5–10 cm from the electrode; however, the soil Cd concentration measured at 0–5 cm for treatment H-5 was 34.84% higher than that of treatment H-0. Our study demonstrated that PRGO could be applied as an auxiliary electrode to promote Cd migration during electrokinetic remediation of Cd-contaminated soil.

Adsorption of Th(IV) from aqueous solution by the graphene oxide nanoribbons/chitosan composite material

In order to reduce the potential toxicity to the environment after treatment of radioactive waste water, an eco-friendly graphene oxide nanoribbons/chitosan (GONRs-CTS) composite was prepared and utilized for adsorption of Th(IV) from aqueous solution. The GONRs-CTS adsorbent was characterized by XRD, FTIR and SEM, indicating that GONRs-CTS contains a large amount of oxygen-containing groups and chitosan was successfully attached to the GONRs surface. The Th(IV) adsorption on GONRs-CTS was endothermic and spontaneous, with the maximum single layer adsorption capacity was 140.6 mg g−1 at pH = 3.0, in the contact time of 12 h. The adsorption process was consistent with pseudo-second-order kinetics and the Langmuir isotherm model.

Stabilization of aqueous graphene oxide with acetone under γ-ray/UV irradiation

Graphene oxide (GO) is a kind of water soluble two-dimensional materials containing a large amount of oxygen-containing groups which infuse GO with water solubility, biocompatibility and functionality, etc. But GO can be easily reduced by losing oxygen-containing groups under some circumstances such as irradiation of $\gamma$ -ray or ultraviolet (UV). In this work, we found that acetone can significantly slow down the reduction process of GO under the irradiation of either $\gamma$ -ray or UV, which was supported by analysis results with UV-visible (UV-Vis) absorption spectra, X-ray photoelectron spectroscopy, etc. Acetone can capture and remove strongly reducible hydrated electrons generated under $\gamma$ -irradiation. GO reduction by UV also involves electron transfer process which can be affected by the presence of acetone. Hence, acetone can be used to stabilize, adjust the radiation reduction process of GO. This would be interesting not only in radiation and radiation protection, but also in understanding the redox properties of GO.

Super-hydrophilicity of hydroxy modified poly(m-phenylenediamine) aerogel for separation of oil/water and biocompatibility

We demonstrate the ultra-light weight and super-hydrophilic hydroxyl modified poly (m-phenylenediamine) (Hy-PmPD) aerogel by utilizing simple oxygen plasma treatment. The average pore size and specific surface area are obtained as 5.21 nm and 671 m2 g−1, respectively. Due to the large amount of oxygen-containing groups (e.g., C–OH and N–OH), the contact angle of Hy-PmPD for water is about 7.2°, which indicates the super-hydrophilic ability of Hy-PmPD. The large surface area and super-hydrophilic nature of ultra- light weight Hy-PmPD aerogel conclusively certify that high absorption capacities and ultrafast absorption rate for water. As a result, the Hy-PmPD aerogel enables to separate crude oil and water. Additionally, the Hy-PmPD aerogel indicates good biocompatibility that can be implanted as the bio-platform for monitoring the cell culture behavior. This work may provide a facile and effective strategy for the applications in the absorption or removal of organics, particularly in environmental protection, pollution control, as well as noninvasive to the microflora.

Graphene Photocatalytic Catalyst Preparation and Properties of Composite Materials Research

Using a pan of the Ag/TiO2/rGO ternary composites, including ethanol as solvent, not only as a reductant in GO with the reduction of silver nitrate, the addition of ammonia water can not only catalytic hydrolysis TBOT to TiO2 can also form with silver nitrate silver ammonia solution is conducive to the reduction of silver nitrate. And the GO surface exist a large amount of oxygen-containing groups can provide nucleation points for the growth of the nanoparticles. Can control the dosing raio of TBOT and GO different morphology of TiO2/rGO composite material is prepared. Photocatalytic degradation of methylene blue test studied Ag modified enhanced the photocatalytic activity of TiO2 light influence.

Insight into the high-efficient functionalization of carbon nanotubes by advanced oxidation using peroxomonosulfate

We report a high-efficient approach for functionalizing carbon nanotubes (CNTs) by utilizing peroxomonosulfate (PMS) coupling with Co(II) ions. Compared with UV/Fenton approach (UF-CNT), the PMS/Co(II) procedure enables superior water dispersibility of the functionalized CNTs (PM-CNT). Both morphological and Raman characterizations show that numerous defects are created upon functionalization, leading to intensive tube wall corrosion and truncation. XPS spectra indicate that both UF-CNT and PM-CNT contain large amounts of oxygen-containing groups. The O content in UF-CNT is dominated by hydroxyl and epoxy species. In contrast, carbonyls are more preferentially planted in PM-CNT. First-principles simulations reveal that the PMS/Co(II) functionalization includes two sequential Steps, during which the adsorbed OH species undergo self-dissociation to form epoxies, followed by the breaking of neighboring C-C bonds as well as the formation of carbonyls. We identified that the HO· radical (exist in both two activation processes) could only functionalize the CNTs to the hydroxyl or epoxy stage, while SO4–· radical (only appears in PMS/Co(II) treatment) will facilitate the conversion of epoxy to carbonyl, in excellent agreement with experimental observations. Our results not only shed light on the insights of the PMS/Co(II) functionalization but provide a transferrable strategy for functionalizing other carbon substrates.

Selective oxidation of hydrocarbons under air using recoverable silver ferrite–graphene (AgFeO2–G) nanocomposite: A good catalyst for green chemistry

The selective oxidation of hydrocarbons is a main academic and industrial research challenge. A lot of researches have been done about this issue, but till now relatively little attention has been paid to graphene-complex oxide nanocomposites. Herein, we report our studies on a new catalyst. Silver ferrite–graphene (AgFeO2–G) as a separable nanocomposite from the reaction solution, was used as an effective oxidizing agent for the oxidation of various hydrocarbons (1- decene, cyclohexene, cis-cycloctene, cyclohexane, cyclooctane etc.) under mild conditions (55০C, 8h) with high conversion and selectivity using air, that is proper for ‘green’ chemistry. Metal or metal oxide nanoparticles assembled on graphene sheets revealed high electrocatalytic activity. Indeed, AgFeO2 with graphene due to low band gap and graphene oxide with large amounts of oxygen-containing groups, provide facility catalytic activity of catalyst-supported system. We also found that, with this catalyst, selective oxidation could be achieved without the need for the addition of solvent, which is appropriate in particular for ‘green’ chemistry. The catalysts showed little deactivation and maintained their conversion and selectivity levels duration of the measurements.

Cytotoxicity Profile of Highly Hydrogenated Graphene

Graphene and its graphene-related counterparts have been considered the future of advanced nanomaterials owing to their exemplary properties. An increase in their potential applications in the biomedical field has led to serious concerns regarding their safety and impact on health. To understand the toxicity profile for a particular type of graphene utilized in a given application, it is important to recognize the differences between the graphene-related components and correlate their cellular toxicity effects to the attributed physiochemical properties. In this study, the cytoxicity effects of highly hydrogenated graphene (HHG) and its graphene oxide (GO) counterpart on the basis of in vitro toxicological assessments are reported and the effects correlated with the physiochemical properties of the tested nanomaterials. Upon 24 h exposure to the nanomaterials, a dose-dependent cellular cytotoxic effect was exhibited and the HHG was observed to be more cytotoxic than its GO control. Detailed characterization revealed an extensive C-H sp(3) network on the carbon backbone of HHG with few oxygen-containing groups, as opposed to the presence of large amounts of oxygen-containing groups on the GO. It is therefore hypothesized that the preferential adsorption of micronutrients on the surface of the HHG nanomaterial by means of hydrophobic interactions resulted in a reduction in the bioavailability of nutrients required for cellular viability. The nanotoxicological profile of highly hydrogenated graphene is assessed for the first time in our study, thereby paving the way for further evaluation of the toxicity risks involved with the utilization of various graphene-related nanomaterials in the real world.

Hydrothermal carbonization of lignocellulosic biomass

Hydrothermal carbonization (HTC) is a novel thermochemical conversion process to convert lignocellulosic biomass into value-added products. HTC processes were studied using two different biomass feedstocks: corn stalk and Tamarix ramosissima. The treatment brought an increase of the higher heating values up to 29.2 and 28.4MJ/kg for corn stalk and T. ramosissima, respectively, corresponding to an increase of 66.8% and 58.3% as compared to those for the raw materials. The resulting lignite-like solid products contained mainly lignin with a high degree of aromatization and a large amount of oxygen-containing groups. Liquid products extracted with ethyl acetate were analyzed by gas chromatography–mass spectrometry. The identified degradation products were phenolic compounds and furan derivatives, which may be desirable feedstocks for biodiesel and chemical production. Based on these results, HTC is considered to be a potential treatment in a lignocellulosic biomass refinery.

Purification and Characterization of Carbon Nanotubes Synthesized by RF-PECVD

In this research, Ni/MgO is used as catalyst and CNTs were synthesized by radio-frequency plasma enhanced chemical vapor deposition (RF-PECVD), and then liquid oxidation method was used to purify CNTs. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), Raman spectroscope and infrared spectroscopy were used to study the influences of purification time on morphology and microstructure of CNTs. The results show that CNTs synthesized by RF-PECVD contain a great amount of impurities. With the increasing of purification time, the impurities decreased. Meanwhile, carboxyl oxygen-containing groups introduced on the surface of CNTs are also gradually increasing along with purification time. And the crystallization properties of CNTs increased first but decreased then with the introduction of a large amount of oxygen-containing groups. The surface modification of CNTs has very important significance for the applications of CNTs in the field of electrochemical biosensor.

Hydrothermal carbonization of biomass as a route for the sequestration of CO2: Chemical and structural properties of the carbonized products

Abstract A highly functionalized carbonaceous material (hydrochar) was obtained by means of the hydrothermal carbonization (250 °C) of two representative types of biomass, i.e. eucalyptus sawdust and barley straw. This product has a brown colour; it contains around 50–60% of the carbon originally present in the biomass and it is composed of particles that retain the cellular appearance of the raw material. These particles are covered by microspheres (1–10 μm) which were probably formed as a consequence of the transformation of the cellulose fraction. From a chemical point of view, the hydrochar products have a high degree of aromatization and they contain a large amount of oxygen-containing groups (i.e. carbonyl, carboxylic, hydroxyl, quinone, ester, etc) as was confirmed by Raman, IR and XPS spectroscopic techniques. The presence of these oxygen functionalities on the surface of the hydrochar particles explains their high water affinity (hydrophilic properties). On the basis of the highly condensed chemical nature of the hydrochar products, we postulated that this material has a recalcitrant nature that could lead to a significant increase in carbon turnover time in relation to the biomass. This suggests an important route for the sequestration of CO 2 present in the atmosphere.

A whisker-like carbon composite for the immobilization of laccase and its bioelectrochemistry

A novel mesoporous carbon/whisker-like carbon (MCWC) composite was used for the immobilization of laccase (Lac) and its bioelectrochemical behaviors were studied. It was confirmed by XPS that Lac was strongly adsorbed on the surface of the MCWC composite. The cyclic voltammetric results showed that the immobilized Lac underwent a direct quasi-reversible electrochemical reaction. The value of the electron transfer rate constant ks was estimated to be 0.770 s−1, indicating a reasonably fast electron transfer between the immobilized Lac and the underlying electrode. The surface concentration (Γ) of Lac was estimated to be 2.730 × 10−12 mol/cm2. Further experimental results showed that the immobilized Lac displayed an appreciable electrocatalytic activity to the electrochemical reduction of O2. These properties could be attributed to the particular structure of loosely packed nanometer-scale carbon whiskers and the existence of a large amount of oxygen-containing groups. The immobilization method and the novel carrier (MCWC) may find new applications in fabricating the biocatalysts for biofuel cells.

Removal of lead from water using biochars prepared from hydrothermal liquefaction of biomass

Hydrothermal conversion of biomass into biofuel could produce a special type of biochar as byproduct. This biochar is quite different from biochar derived from high temperature pyrolysis. In the present study, two biochars, prepared from hydrothermal liquefaction of pinewood (P300) and rice husk (R300), were characterized and investigated for lead removal from aqueous solution. The results indicated that the biochars contained a large amount of oxygen-containing groups on the surface, which were quite effective for lead removal with capacities of 4.25 and 2.40 mg/g for P300 and R300, respectively. The adsorption equilibrium was achieved around 5 h. Higher temperature favored the removal capacity implying that the adsorption was an endothermic process. The adsorption data at optimum solution pH 5 could be well described by Langmuir model and the adsorption process was well fitted by pseudo-second-order model. Moreover, it was found that the adsorption was mainly controlled by film diffusion. Thermodynamics analysis suggested that lead adsorption onto the biochars was physical endothermic process.