scholarly journals Comparing Graphene Oxide and Reduced Graphene Oxide as Blending Materials for Polysulfone and Polyvinylidene Difluoride Membranes

2020 ◽  
Vol 10 (6) ◽  
pp. 2015 ◽  
Author(s):  
Yeojoon Yoon ◽  
Homin Kye ◽  
Woo Seok Yang ◽  
Joon-Wun Kang
Keyword(s):  
Graphene Oxide ◽  
Reduced Graphene Oxide ◽  
Functional Groups ◽  
Polyvinylidene Fluoride ◽  
Membrane Surface ◽  
Atomic Plane ◽  
Inversion Method ◽  
Pristine Graphene ◽  
Reduced Graphene ◽  
Phase Inversion Method

Graphene is a single atomic plane of graphite, and it exhibits unique electronic, thermal, and mechanical properties. Exfoliated graphene oxide (GO) contains various hydrophilic functional groups, such as hydroxyl, epoxide, and carboxyl groups, that can modify the hydrophobic characteristics of a membrane surface. Though reduced graphene oxide (rGO) has fewer functional groups than GO, its associated sp2 structures and physical properties can be recovered. A considerable amount of research has focused on the use of GO to obtain a pristine graphene material via reduction processes. In this study, polysulfone (PSf) and polyvinylidene fluoride (PVDF) membranes that were blended with GO and rGO, respectively, were fabricated by using the immersion phase inversion method and an n-methylpyrrolidone (NMP) solvent. Results showed that the graphene nanomaterials, GO and rGO, can change the pore morphology (size and structure) of both PSf and PVDF membranes. The optimum content of both was then investigated, and the highest flux enhancement was observed with the 0.10 wt% GO-blended PSf membrane. The presence of functional groups in GO within prepared PSf and PVDF membranes alters the membrane characteristics to hydrophilic. An antifouling test and rejection efficiency evaluation also showed that the 0.10 wt% membrane provided the best performance.

scholarly journals The Influence of Graphene Addition on the Properties of Composite rGO/PAN Membranes and Their Potential Application for Water Disinfection

Membranes ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 58 ◽  
Author(s):  
Beata Fryczkowska ◽  
Alicja Machnicka ◽  
Dorota Biniaś ◽  
Czesław Ślusarczyk ◽  
Janusz Fabia
Keyword(s):  
Graphene Oxide ◽  
Reduced Graphene Oxide ◽  
Composite Membranes ◽  
Water Disinfection ◽  
Inversion Method ◽  
Protein Retention ◽  
Reduced Graphene ◽  
Phase Inversion Method ◽  
High Degree ◽  
The Impact

The paper presents a method of obtaining composite polyacrylonitrile-based (PAN) membranes with the addition of reduced graphene oxide (rGO). The membranes were obtained using phase inversion method from a homogeneous rGO dispersion in a solution of PAN dissolved in N, N-dimethylformamide (DMF). The impact of the amount of rGO addition to the PAN matrix on the physicochemical, structural, transport, and separation properties and on fouling resistance was studied. Composite membranes, due to the method of preparation used and the addition of rGO, are characterized by very good transport properties (~390 L/m2 h) and by a high degree of protein retention (85%). Reduced graphene oxide has biocidal properties, which, as we have shown, depend on the size of nanoparticles and the type of microorganism. rGO/PAN membranes, on the other hand, show biostatic properties against Gram-negative bacteria (Escherichia coli), Gram-positive bacteria (Staphylococcuc aureus) and fungi (Candida albicans). Thus, the obtained composite membranes can be potentially used in water disinfection.

scholarly journals Functionalized Reduced Graphene Oxide Thin Films for Ultrahigh CO2 Gas Sensing Performance at Room Temperature

Nanomaterials ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 623
Author(s):  
Monika Gupta ◽  
Huzein Fahmi Hawari ◽  
Pradeep Kumar ◽  
Zainal Arif Burhanudin ◽  
Nelson Tansu
Keyword(s):  
Thin Films ◽  
Graphene Oxide ◽  
Reduced Graphene Oxide ◽  
Gas Sensor ◽  
Functional Groups ◽  
Recovery Time ◽  
Room Temperature ◽  
Co2 Gas ◽  
Reduced Graphene ◽  
Response And Recovery

The demand for carbon dioxide (CO2) gas detection is increasing nowadays. However, its fast detection at room temperature (RT) is a major challenge. Graphene is found to be the most promising sensing material for RT detection, owing to its high surface area and electrical conductivity. In this work, we report a highly edge functionalized chemically synthesized reduced graphene oxide (rGO) thin films to achieve fast sensing response for CO2 gas at room temperature. The high amount of edge functional groups is prominent for the sorption of CO2 molecules. Initially, rGO is synthesized by reduction of GO using ascorbic acid (AA) as a reducing agent. Three different concentrations of rGO are prepared using three AA concentrations (25, 50, and 100 mg) to optimize the material properties such as functional groups and conductivity. Thin films of three different AA reduced rGO suspensions (AArGO25, AArGO50, AArGO100) are developed and later analyzed using standard FTIR, XRD, Raman, XPS, TEM, SEM, and four-point probe measurement techniques. We find that the highest edge functionality is achieved by the AArGO25 sample with a conductivity of ~1389 S/cm. The functionalized AArGO25 gas sensor shows recordable high sensing properties (response and recovery time) with good repeatability for CO2 at room temperature at 500 ppm and 50 ppm. Short response and recovery time of ~26 s and ~10 s, respectively, are achieved for 500 ppm CO2 gas with the sensitivity of ~50 Hz/µg. We believe that a highly functionalized AArGO CO2 gas sensor could be applicable for enhanced oil recovery, industrial and domestic safety applications.

Modulation of oxygen functional groups and their influence on the supercapacitor performance of reduced graphene oxide

2020 ◽  
Vol 44 (44) ◽  
pp. 19022-19027
Author(s):  
Zegao Wang ◽  
Yuqing Wang ◽  
Xin Hao ◽  
Jingbo Liu ◽  
Yuanfu Chen ◽  
...  
Keyword(s):  
Graphene Oxide ◽  
Specific Capacitance ◽  
Reduced Graphene Oxide ◽  
Functional Groups ◽  
Oxygen Functional Groups ◽  
Reduced Graphene ◽  
Supercapacitor Performance

Through tuning the oxygen function groups, it was demonstrated that the specific capacitance of reduced graphene oxide can increase from 136 F g−1 to 182 F g−1.

The influence of oxygen functional groups on gas-sensing properties of reduced graphene oxide (rGO) at room temperature

RSC Advances ◽  
2016 ◽  
Vol 6 (57) ◽  
pp. 52339-52346 ◽  
Author(s):  
X. Wang ◽  
X. Li ◽  
Y. Zhao ◽  
Y. Chen ◽  
J. Yu ◽  
...  
Keyword(s):  
Graphene Oxide ◽  
Reduced Graphene Oxide ◽  
Functional Groups ◽  
Room Temperature ◽  
Gas Sensing ◽  
Sensing Properties ◽  
Oxygen Functional Groups ◽  
Reduced Graphene ◽  
Gas Sensing Properties

Three methods were used to prepare reduced graphene oxide (rGO) with various ratios of oxygen functional groups, such as –OOH, –OH and CO, to study their effects on the NO2 sensing properties at room temperature.

scholarly journals Graphene oxide-multiwalled carbon nanotubes composite as an anode for lithium ion batteries

2016 ◽  
Vol 34 (3) ◽  
pp. 481-486 ◽  
Author(s):  
Łukasz Majchrzycki ◽  
Mariusz Walkowiak ◽  
Agnieszka Martyła ◽  
Mikhail Y. Yablokov ◽  
Marek Nowicki ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Graphene Oxide ◽  
Lithium Ion Batteries ◽  
Reduced Graphene Oxide ◽  
Multiwalled Carbon Nanotubes ◽  
Functional Groups ◽  
Lithium Ion ◽  
Lithium Storage ◽  
Multiwalled Carbon ◽  
Reduced Graphene

AbstractNowadays reduced graphene oxide (rGO) is regarded as a highly interesting material which is appropriate for possible applications in electrochemistry, especially in lithium-ion batteries (LIBs). Several methods were proposed for the preparation of rGO-based electrodes, resulting in high-capacity LIBs anodes. However, the mechanism of lithium storage in rGO and related materials is still not well understood. In this work we focused on the proposed mechanism of favorable bonding sites induced by additional functionalities attached to the graphene planes. This mechanism might increase the capacity of electrodes. In order to verify this hypothesis the composite of non-reduced graphene oxide (GO) with multiwalled carbon nanotubes electrodes was fabricated. Electrochemical properties of GO composite anodes were studied in comparison with similarly prepared electrodes based on rGO. This allowed us to estimate the impact of functional groups on the reversible capacity changes. As a result, it was shown that oxygen containing functional groups of GO do not create, in noticeable way, additional active sites for the electrochemical reactions of lithium storage, contrary to what has been postulated previously.

Ultrasensitive Chemical Sensing through Facile Tuning Defects and Functional Groups in Reduced Graphene Oxide

2014 ◽  
Vol 86 (15) ◽  
pp. 7516-7522 ◽  
Author(s):  
Shumao Cui ◽  
Haihui Pu ◽  
Eric C. Mattson ◽  
Zhenhai Wen ◽  
Jingbo Chang ◽  
...  
Keyword(s):  
Graphene Oxide ◽  
Reduced Graphene Oxide ◽  
Functional Groups ◽  
Chemical Sensing ◽  
Reduced Graphene

Synthesis of reduced graphene oxide paper for EMI shielding by a multi-step process

2020 ◽  
Vol 13 (05) ◽  
pp. 2051024
Author(s):  
Yangyang Lin ◽  
Genliang Hou ◽  
Song Bi ◽  
Xunjia Su ◽  
Hao Li
Keyword(s):  
Graphene Oxide ◽  
Reduced Graphene Oxide ◽  
Functional Groups ◽  
Electromagnetic Interference ◽  
Reduction Process ◽  
Emi Shielding ◽  
Hydroiodic Acid ◽  
X Band ◽  
Reduced Graphene ◽  
Graphene Oxide Paper

A multi-step reduction process was developed to produce reduced graphene oxide (rGO) paper for electromagnetic interference (EMI) shielding. First step reduction was achieved by hydroiodic acid to remove most of the oxygen-containing functional groups, and sodium borohydride was used in the second step reduction to reduce carbonyl group which is the most difficult functional group to remove. In the last step reduction, hydroiodic acid was used as reducing agent again to remove the remaining oxygen-containing functional groups. The results show that this method can greatly improve the conductivity and EMI shielding performance of rGO paper. The resulting rGO paper with a C/O ratio of 19.38 and a thickness of 9.1[Formula: see text][Formula: see text]m exhibited high conductivity of 1084[Formula: see text]S/cm and excellent average EMI shielding efficiency of 45.84[Formula: see text]dB in the X-band, better than that reduction by other chemical methods.

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