Electrochemical hydrogen production from humid air using cation-modified graphene oxide membranes

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Nur Laila Hamidah ◽  
Masataka Shintani ◽  
Aynul Sakinah Ahmad Fauzi ◽  
Shota Kitamura ◽  
Elaine G. Mission ◽  
...  
Keyword(s):  
Graphene Oxide ◽  
Proton Conductivity ◽  
Room Temperature ◽  
Electrochemical Impedance ◽  
Water Electrolysis ◽  
Proton Conductors ◽  
X Ray ◽  
Chemical Structures ◽  
Modified Graphene Oxide ◽  
Modified Graphene

AbstractWater electrolysis is an environment-friendly process of producing hydrogen with zero-carbon emission. Herein, we studied the water vapor electrolysis using a proton-conducting membrane composed of graphene oxide (GO) nanosheets intercalated with cations (Al3+ and Ce3+). We examined the effect of cation introduction on the physical and chemical structures, morphology, thermal and chemical stabilities, and the proton conductivity of stacked GO nanosheet membranes by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), X-ray photoemission spectroscopy (XPS), Raman spectroscopy, atomic force microscopy (AFM), dynamic light scattering (DLS), thermogravimetric-differential thermal analysis (TG-DTA), and electrochemical impedance spectroscopy (EIS). Concentration cell measurements revealed that the cation-modified membranes are pure proton conductors at room temperature. The proton conductivity of a GO membrane was much improved by cation modification. The cation-modified GO membranes, sandwiched with Pt/C electrodes as the cathode and anode, electrolyzed humidified air to produce hydrogen at room temperature, indicating the feasibility of this carbon-based electrochemical device.

scholarly journals Hydrophobic Modification of Graphene Oxide and Its Effect on the Corrosion Resistance of Silicone-Modified Epoxy Resin

Metals ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 89
Author(s):  
Wei Yuan ◽  
Qian Hu ◽  
Jiao Zhang ◽  
Feng Huang ◽  
Jing Liu
Keyword(s):  
Contact Angle ◽  
Corrosion Resistance ◽  
Graphene Oxide ◽  
Physical Properties ◽  
Epoxy Resin ◽  
Electrochemical Impedance ◽  
Salt Spray ◽  
X Ray ◽  
Modified Graphene Oxide ◽  
Modified Epoxy

This study modified graphene oxide (GO) with hydrophilic octadecylamine (ODA) via covalent bonding to improve its dispersion in silicone-modified epoxy resin (SMER) coatings. The structural and physical properties of ODA-GO were characterized by field-emission scanning electron microscopy (FE-SEM), X-ray diffraction analysis (XRD), Fourier transform infrared spectroscopy (FT-IR), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), and contact angle tests. The ODA-GO composite materials were added to SMER coatings by physical mixing. FE-SEM, water absorption, and contact angle tests were used to evaluate the physical properties of the ODA-GO/SMER coatings, while salt spray, electrochemical impedance spectroscopy (EIS), and scanning Kelvin probe (SKP) methods were used to test the anticorrosive performance of ODA-GO/SMER composite coatings on Q235 steel substrates. It was found that ODA was successfully grafted onto the surfaces of GO. The resulting ODA-GO material exhibited good hydrophobicity and dispersion in SMER coatings. The anticorrosive properties of the ODA-GO/SMER coatings were significantly improved due to the increased interfacial adhesion between the nanosheets and SMER, lengthening of the corrosive solution diffusion path, and increased cathodic peeling resistance. The 1 wt.% ODA-GO/SMER coating provided the best corrosion resistance than SMER coatings with other amounts of ODA-GO (including no addition). After immersion in 3.5 wt.% NaCl solution for 28 days, the low-frequency end impedance value of the 1 wt.% ODA-GO/SMER coating remained high, at 6.2 × 108 Ω·cm2.

scholarly journals Citrus Extract Modified Graphene Oxide as a Green and Heterogeneous Organocatalyst for the Synthesis of Imidazole Derivatives

2020 ◽  
Vol 32 (9) ◽  
pp. 2375-2380
Author(s):  
S. ARUNKUMAR ◽  
S. CHIDAMBARA VINAYAGAM ◽  
S. LAKSHMANAN ◽  
S. ARUL ANTONY
Keyword(s):  
Electron Microscopy ◽  
Graphene Oxide ◽  
Catalytic Activity ◽  
Room Temperature ◽  
Fourier Transforms ◽  
X Ray ◽  
Imidazole Derivatives ◽  
Modified Graphene Oxide ◽  
Citrus Extract ◽  
Microscopy Images

A naturally benign convention was created with a surface change of graphene oxide by citrus extract as catalyst was prepared by a straight-forward chemical modification method. The prepared catalyst′s catalytic activity was examined by the synthesis of imidazole derivatives at room temperature. It shows a strong acidic catalytic and sustainable organocatalyst. The prepared catalyst was characterized using different analytical procedures like elemental analysis, Fourier transforms infrared spectroscopy (FT-IR), powder X-ray diffraction (PXRD), energy-dispersive X-ray analysis (EDS), scanning electron microscopy images (SEM) and transmission electron microscopy images (TEM) analysis. The catalytic activity shows high activity and can be reused without significant loss of catalytic activity after five times. A present catalyst works easily under room temperature.

Glycine modified graphene oxide as a novel sorbent for preconcentration of chromium, copper, and zinc ions from water samples prior to energy dispersive X-ray fluorescence spectrometric determination

RSC Advances ◽  
2016 ◽  
Vol 6 (49) ◽  
pp. 42836-42844 ◽  
Author(s):  
Katarzyna Pytlakowska ◽  
Violetta Kozik ◽  
Marek Matussek ◽  
Michał Pilch ◽  
Barbara Hachuła ◽  
...  
Keyword(s):  
Graphene Oxide ◽  
Solid Phase Extraction ◽  
Solid Phase ◽  
Phase Extraction ◽  
Zinc Ions ◽  
Chemical Functionalization ◽  
X Ray ◽  
Selective Sorbent ◽  
Modified Graphene Oxide ◽  
Modified Graphene

A novel and selective sorbent for micro-solid phase extraction was synthesized by chemical functionalization of graphene oxide with glycine.

scholarly journals Improvement of Dispersibility of Graphene Oxide by Surface Modification with Rare Earths

2022 ◽  
Author(s):  
Yong Li ◽  
Zhou Jiang ◽  
Haidong Yu ◽  
Xuebin Zhou ◽  
Peng Yi
Keyword(s):  
Electron Microscopy ◽  
Graphene Oxide ◽  
Rare Earth ◽  
Rare Earth Elements ◽  
Photoelectron Spectroscopy ◽  
Energy Dispersive Spectrometer ◽  
X Ray ◽  
Modified Graphene Oxide ◽  
Modified Graphene ◽  
The Rare Earth

Abstract Rare earth-modified graphene oxide (RE-M-GO) materials were successfully prepared by infiltration and heating modifier method. The morphology and phase structure of RE-M-GO were characterized by scanning electron microscopy(SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and energy dispersive spectrometer(EDS). The changes of the chemical structure were indicated by Fourier transform infrared (FTIR). X-ray photoelectron spectroscopy(XPS) was used to study the chemical state of the surface elements of graphene oxide which showed that the rare earth elements were added to the graphene oxide functional groups through the coordination reaction. Additionally, the findings concluded that the effect of modification by Ce is more obvious than La elements and the RE-M-GO materials prepared by the heating modifier method had better dispersibility than infiltration. With activating effect, the rare earth elements grafting to graphene oxide will contribute to its combination with other materials.

Preparation and Properties of Tea Polyphenol Modified Graphene Oxide/Epoxy Resin Composites

2019 ◽  
Vol 814 ◽  
pp. 3-11
Author(s):  
Xiang Yu Ren ◽  
Hui Chen ◽  
Jing Wu ◽  
Hong Bo Liu
Keyword(s):  
Graphene Oxide ◽  
Epoxy Resin ◽  
Thermo Gravimetric Analysis ◽  
Testing Machine ◽  
Gravimetric Analysis ◽  
Resin Composites ◽  
X Ray ◽  
Modified Graphene Oxide ◽  
Epoxy Resin Composites ◽  
Modified Graphene

Microcrystalline graphite (MG) was used as raw material and oxidated by Hummers method. And further the graphene oxide (GO) was obtained by ultrasonic stripping. The TP modified graphene (TPG) was prepared by the surface grafting of pure natural green tea extract tea polyphenols (TP) on the surface of GO. Finally, the TPG/epoxy resin composite was prepared by solution blending and heat-curing moulding method.The characterization of structure and properties of TPG was analyzed by X ray diffraction pattern (XRD), infrared spectroscopy (FT-IR), thermo gravimetric analysis (TGA) and X ray photoelectron spectroscopy (XPS). A universal material testing machine was used to test the mechanical properties of epoxy resin composites with different addition of TPG. Field emission scanning electron microscopy (SEM) was used to observe the tensile-sectional morphology of the composites. The thermal stability of the composites was investigated by thermogravimetry and thermal dilatometer. The experimental results showed that the TP molecule was successfully grafted on the oxygen-containing functional groups of the GO surface through the phenolic hydroxyl group.When the addition of TPG was 1.0 wt%, the decomposition temperature of the epoxy resin was increased by 22.2 °C,and the surface resistivity decreased from 1.35×1014 Ω·m to 1.7×109 Ω·m. When the added amount of TPG was 0.5 wt%, the tensile strength of composites was increased by 13.5% reaching 59.85 MPa.

scholarly journals Polydopamine Modified Graphene Oxide-TiO2 Nanofiller for Reinforcing Physical Properties and Anticorrosion Performance of Waterborne Epoxy Coatings

2019 ◽  
Vol 9 (18) ◽  
pp. 3760 ◽  
Author(s):  
Shuli Wang ◽  
Jiankang Zhu ◽  
Yongchao Rao ◽  
Beibei Li ◽  
Shuhua Zhao ◽  
...  
Keyword(s):  
Graphene Oxide ◽  
Physical Properties ◽  
Epoxy Resin ◽  
Nano Tio2 ◽  
X Ray ◽  
Tio2 Particles ◽  
Modified Graphene Oxide ◽  
Waterborne Epoxy ◽  
Waterborne Epoxy Resin ◽  
Modified Graphene

Nano-polydopamine-graphene oxide-TiO2 (nano-PDA@GO-TiO2) composites were prepared by dopamine modified graphene oxide (GO) and loaded nano-TiO2 on the surface of GO. The structure and morphology of nano-PDA@GO-TiO2 composites were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), Raman, X-ray photoelectron spectroscopy (XPS), Scanning electron microscope (SEM), and Transmission electron microscope (TEM) Results demonstrate that the introduction of dopamine to functionalize the GO could self-polymerize polydopamine (PDA) on the surfaces of the GO and endow abundant chemical groups reduce the GO. The interaction between the GO and nano-TiO2 particles could prevent graphene nanosheets from restacking and nano-TiO2 particles from agglomeration. Nano-PDA@GO-TiO2 composite material was used as the nano-filler, and nano-PDA@GO-TiO2 composites waterborne epoxy resin coatings (PGT/WEP) were prepared by dispersing a different content of nano-PDA@GO-TiO2 composites into waterborne epoxy resin with the help of ultrasonic dispersion and mechanical agitation. The physical properties of PGT/WEP coatings, such as hardness, impact resistance, and adhesion, were tested and the electrochemical performance was evaluated. The results show that dispersing 2% nano-PDA@GO-TiO2 composites in waterborne epoxy resin could significantly improve the physical properties and corrosion resistance of waterborne epoxy resin coating when compared with pure waterborne epoxy coating.

scholarly journals Effect of modified graphene oxide on Cu and phosphorus in eutrophic river sediments

2020 ◽  
Vol 82 (4) ◽  
pp. 787-798
Author(s):  
Zhipeng Lin ◽  
Lei Song ◽  
Baohong Han ◽  
Hao Li ◽  
Qian Wang
Keyword(s):  
Graphene Oxide ◽  
Interstitial Water ◽  
Yellow River ◽  
Organic Phosphorus ◽  
River Sediments ◽  
Water Safety ◽  
Magnetic Graphene Oxide ◽  
X Ray ◽  
Modified Graphene Oxide ◽  
Modified Graphene

Abstract Ulansuhai nur is located in the cold and dry area of China, and the management of heavy metals in the sediments is related to water safety in the lower places of the Yellow River. Graphene oxide (GO) is modified to obtain magnetic graphene oxide (G-F) and chitosan grafted graphene oxide (G-N-C) materials, which are used to immobilize Cu in the sediments. The modified materials are characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and X-ray diffractometer (XRD). G-F respectively reduces the concentration of Cu in the overlying and interstitial water by 61.5–66.3% and 22.4–47.1%, which is more effective than GO and G-N-C. Experiments are designed to determine the effect of phosphates concentration on immobilizing Cu in the sediments by modified materials. The results show that a low concentration of phosphates solution is beneficial to the immobilization of Cu in the sediments, and the capability of G-F to immobilize Cu is higher than that of GO and G-N-C. G-F presents a lower increase in organic phosphorus in the sediments than GO and G-N-C. In summary, the modified materials can immobilize Cu in the sediments, potentially reduce the water body eutrophication, and improve the lake ecological environment.

scholarly journals Organic Functionalized Graphene Oxide Behavior in Water

Nanomaterials ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 1228
Author(s):  
Changwoo Kim ◽  
Junseok Lee ◽  
Will Wang ◽  
John Fortner
Keyword(s):  
Graphene Oxide ◽  
Divalent Cations ◽  
Critical Role ◽  
Functionalized Graphene Oxide ◽  
Organic Functionalization ◽  
Chemical Structures ◽  
Modified Graphene Oxide ◽  
Surface Modified ◽  
Modified Graphene ◽  
Hydrophilic Coatings

Surface modified graphene oxide (GO) has received broad interest as a potential platform material for sensors, membranes, and sorbents, among other environmental applications. However, compared to parent (unmodified) GO, there is a dearth of information regarding the behavior of subsequently (secondary) modified GO, other than bulk natural organic matter (NOM) coating(s). Here, we systematically explore the critical role of organic functionalization with respect to GO stability in water. Specifically, we synthesized a matrix of GO-based materials considering a carefully chosen range of bound organic molecules (hydrophobic coatings: propylamine, tert-octylamine, and 1-adamantylamine; hydrophilic coatings: 3-amino-1-propanol and 3-amino-1-adamantanol), so that chemical structures and functional groups could be directly compared. GO (without organic functionalization) with varying oxidation extent(s) was also included for comparison. The material matrix was evaluated for aqueous stability by comparing critical coagulation concentration (CCC) as a function of varied ionic strength and type (NaCl, CaCl2, MgCl2, and MgSO4) at pH 7.0. Without surface derivatization (i.e., pristine GO), increased stability was observed with an increase in the GO oxidation state, which is supported by plate–plate Derjaguin, Landau, Verwey and Overbeek (DLVO) energy interaction analyses. For derivatized GO, we observed that hydrophilic additions (phi-GO) are relatively more stable than hydrophobic organic coated GO (pho-GO). We further explored this by altering a single OH group in the adamantane-x structure (3-amino-1-adamantanol vs. 1-adamantylamine). As expected, Ca2+ and monovalent co-ions play an important role in the aggregation of highly oxidized GO (HGO) and phi-GO, while the effects of divalent cations and co-ions were less significant for pho-GO. Taken together, this work provides new insight into the intricate dynamics of GO-based material stability in water as it relates to surface functionalization (surface energies) and ionic conditions including type of co- and counter-ion, valence, and concentration.

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