scholarly journals Exploration of reduced graphene oxide microparticles as electrocatalytic materials in vanadium redox flow batteries

2021 ◽  
Author(s):  
Amira Alazmi ◽  
Charles Wan ◽  
Pedro Costa ◽  
Fikile Brushett
Keyword(s):  
Graphene Oxide ◽  
Critical Point ◽  
Reduced Graphene Oxide ◽  
Surface Area ◽  
Reaction Rates ◽  
Redox Flow Batteries ◽  
Reduced Graphene ◽  
Critical Point Drying ◽  
Flow Batteries ◽  
Vanadium Redox

Augmenting reaction rates on porous carbon electrodes is critical for reducing the cost of all-vanadium redox flow batteries (VRFBs). To this end, reduced graphene oxide (rGO) based carbons hold promise, demonstrating high specific surface area, chemomechanical stability, and electrochemical activity. While initial efforts have shown that rGOs can enhance VRFB performance, the range of unique processing conditions leads to a collection of materials with disparate elemental composition and porous structure, thus obscuring performance-determining characteristics behind redox reactions and frustrating the development of generalizable design principles. Here, we generate rGO electrocatalysts of nearly identical chemical composition but different textures (i.e., surface area and pore structure) by varying the drying step in the graphene synthesis (i.e., vacuum-drying vs. carbon dioxide critical point drying). We apply spectroscopic and electrochemical techniques on the synthesized rGOs, observing a three-fold increase in BET surface area using critical point drying. We subsequently decorate carbon felt electrodes – both pristine and thermally activated – with rGO microparticles via a flow deposition procedure, and evaluate their performance and durability in a VRFB cell. The synthesis approach and findings described in this work inform and complement efforts to advance the material science and engineering of rGO electrocatalysts.

Electrodeposited reduced graphene oxide as a highly efficient and low-cost electrocatalyst for vanadium redox flow batteries

2019 ◽  
Vol 297 ◽  
pp. 31-39 ◽  
Author(s):  
Pooria Moozarm Nia ◽  
Ebrahim Abouzari-Lotf ◽  
Pei Meng Woi ◽  
Yatimah Alias ◽  
Teo Ming Ting ◽  
...  
Keyword(s):  
Graphene Oxide ◽  
Reduced Graphene Oxide ◽  
Low Cost ◽  
Redox Flow Batteries ◽  
Highly Efficient ◽  
Reduced Graphene ◽  
Flow Batteries ◽  
Vanadium Redox

RuSe/reduced graphene oxide: an efficient electrocatalyst for VO2+/VO2+ redox couples in vanadium redox flow batteries

RSC Advances ◽  
2014 ◽  
Vol 4 (39) ◽  
pp. 20379-20381 ◽  
Author(s):  
Pengxian Han ◽  
Xiaogang Wang ◽  
Lixue Zhang ◽  
Tianshi Wang ◽  
Jianhua Yao ◽  
...  
Keyword(s):  
Graphene Oxide ◽  
Reduced Graphene Oxide ◽  
Redox Flow Batteries ◽  
Redox Couples ◽  
Electrocatalytic Performance ◽  
Reduced Graphene ◽  
Flow Batteries ◽  
Vanadium Redox

Selenium modified ruthenium/reduced graphene oxide (RuSe/rGO) exhibits excellent electrocatalytic performance towards VO2+/VO2+ redox couples in vanadium redox flow batteries.

Synergistic effects of a TiNb2O7–reduced graphene oxide nanocomposite electrocatalyst for high-performance all-vanadium redox flow batteries

2018 ◽  
Vol 6 (28) ◽  
pp. 13908-13917 ◽  
Author(s):  
Anteneh Wodaje Bayeh ◽  
Daniel Manaye Kabtamu ◽  
Yu-Chung Chang ◽  
Guan-Cheng Chen ◽  
Hsueh-Yu Chen ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
Graphene Oxide ◽  
High Performance ◽  
Freeze Drying ◽  
Synergistic Effects ◽  
Low Cost ◽  
Redox Flow Batteries ◽  
Reduced Graphene ◽  
Flow Batteries ◽  
Vanadium Redox

In this study, a simple, low-cost, and powerful titanium niobium oxidereduced graphene oxide (TiNb2O7–rGO) nanocomposite electrocatalyst was synthesized through dispersion and blending in aqueous solution followed by freeze-drying and annealing for all-vanadium redox flow batteries (VRFBs).

scholarly journals Synergistic Catalysis of SnO2/Reduced Graphene Oxide for VO2+/VO2+ and V2+/V3+ Redox Reactions

Molecules ◽  
2021 ◽  
Vol 26 (16) ◽  
pp. 5085
Author(s):  
Yongguang Liu ◽  
Yingqiao Jiang ◽  
Yanrong Lv ◽  
Zhangxing He ◽  
Lei Dai ◽  
...  
Keyword(s):  
Graphene Oxide ◽  
Metal Oxide ◽  
Reduced Graphene Oxide ◽  
Surface Area ◽  
Redox Reaction ◽  
Redox Reactions ◽  
Transport Processes ◽  
Electrochemical Kinetics ◽  
Reduced Graphene ◽  
Vanadium Redox

In spite of their low cost, high activity, and diversity, metal oxide catalysts have not been widely applied in vanadium redox reactions due to their poor conductivity and low surface area. Herein, SnO2/reduced graphene oxide (SnO2/rGO) composite was prepared by a sol–gel method followed by high-temperature carbonization. SnO2/rGO shows better electrochemical catalysis for both redox reactions of VO2+/VO2+ and V2+/V3+ couples as compared to SnO2 and graphene oxide. This is attributed to the fact that reduced graphene oxide is employed as carbon support featuring excellent conductivity and a large surface area, which offers fast electron transfer and a large reaction place towards vanadium redox reaction. Moreover, SnO2 has excellent electrochemical activity and wettability, which also boost the electrochemical kinetics of redox reaction. In brief, the electrochemical properties for vanadium redox reactions are boosted in terms of diffusion, charge transfer, and electron transport processes systematically. Next, SnO2/rGO can increase the energy storage performance of cells, including higher discharge electrolyte utilization and lower electrochemical polarization. At 150 mA cm−2, the energy efficiency of a modified cell is 69.8%, which is increased by 5.7% compared with a pristine one. This work provides a promising method to develop composite catalysts of carbon materials and metal oxide for vanadium redox reactions.

scholarly journals Analysis of the Performance of Phosphorus and Sulphur Co-Doped Reduced Graphene Oxide as Catalyst in Vanadium Redox Flow Battery

2022 ◽  
Author(s):  
Qiang Li ◽  
Junnan Wang ◽  
Tianyu Zhang ◽  
Zinan Wang ◽  
Zhichao Xue ◽  
...  
Keyword(s):  
Graphene Oxide ◽  
Catalytic Activity ◽  
Specific Surface ◽  
Reduced Graphene Oxide ◽  
Surface Area ◽  
Vanadium Redox Flow Battery ◽  
Redox Flow Battery ◽  
Reduced Graphene ◽  
Vanadium Redox ◽  
Co Doped

Abstract In a vanadium redox flow battery, the traditional polyacrylonitrile based graphite felt (GF) electrode suffers the problems of low electrochemical catalytic activity and low specific surface area. To improve the performance of the GF electrode, we prepared phosphorus and sulphur co-doped reduced graphene oxide (PS-rGO) as catalyst with the simple treatment of reduced graphene oxide (rGO) in the mixture of phytic acid and sulfuric acid. The GF electrode modified with PS-rGO (PS-rGO-GF) was characterized by scanning electron microscope, specific surface area, X-ray photoelectron spectroscopy, cyclic voltammetry, electrochemical impedance spectroscopy, and charge-discharge tests. The PS-rGO-GF shows enhanced performance toward VO2+/VO2+ redox reaction. The battery with the PS-rGO decorated GF presents an excellent battery performance with the energy efficiency of 81.37 % at the current density of 80 mA cm-2 and the corresponding discharge capacity of 772 mAh due to the high catalytic activity of PS-rGO.

scholarly journals Reduced Graphene Oxide-Supported Pt-Based Catalysts for PEM Fuel Cells with Enhanced Activity and Stability

Catalysts ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 256
Author(s):  
Irina V. Pushkareva ◽  
Artem S. Pushkarev ◽  
Valery N. Kalinichenko ◽  
Ratibor G. Chumakov ◽  
Maksim A. Soloviev ◽  
...  
Keyword(s):  
Graphene Oxide ◽  
Reduced Graphene Oxide ◽  
Surface Area ◽  
Pem Fuel Cells ◽  
Polyol Process ◽  
Proton Exchange ◽  
Active Surface Area ◽  
Electrochemical Performances ◽  
Simultaneous Reduction ◽  
Reduced Graphene

Platinum (Pt)-based electrocatalysts supported by reduced graphene oxide (RGO) were synthesized using two different methods, namely: (i) a conventional two-step polyol process using RGO as the substrate, and (ii) a modified polyol process implicating the simultaneous reduction of a Pt nanoparticle precursor and graphene oxide (GO). The structure, morphology, and electrochemical performances of the obtained Pt/RGO catalysts were studied and compared with a reference Pt/carbon black Vulcan XC-72 (C) sample. It was shown that the Pt/RGO obtained by the optimized simultaneous reduction process had higher Pt utilization and electrochemically active surface area (EASA) values, and a better performance stability. The use of this catalyst at the cathode of a proton exchange membrane fuel cell (PEMFC) led to an increase in its maximum power density of up to 17%, and significantly enhanced its performance especially at high current densities. It is possible to conclude that the optimized synthesis procedure allows for a more uniform distribution of the Pt nanoparticles and ensures better binding of the particles to the surface of the support. The advantages of Pt/RGO synthesized in this way over conventional Pt/C are the high electrical conductivity and specific surface area provided by RGO, as well as a reduction in the percolation limit of the components of the electrocatalytic layer due to the high aspect ratio of RGO.

Synthesis of reduced graphene oxide/aluminum nanocomposites via chemical-mechanical processes

2018 ◽  
Vol 52 (22) ◽  
pp. 3015-3025 ◽  
Author(s):  
Daeyoung Kim ◽  
Heon Kang ◽  
Donghyun Bae ◽  
Seungjin Nam ◽  
Manuel Quevedo-Lopez ◽  
...  
Keyword(s):  
Graphene Oxide ◽  
Polyvinyl Alcohol ◽  
Specific Surface ◽  
Reduced Graphene Oxide ◽  
Surface Area ◽  
Specific Surface Area ◽  
Aluminum Powder ◽  
Mechanical Milling ◽  
Uniform Dispersion ◽  
Reduced Graphene

The present study employed a combination of solution-based synthesis and mechanical milling to develop reduced graphene oxide/aluminum composites, in order to achieve uniform dispersion of reduced graphene oxide and strong interfaces between reduced graphene oxide and aluminum. First, spherical aluminum powder was flattened via mechanical milling to afford a large specific surface area and many reaction sites for the graphene oxide. A hydrophilic surface was then created by coating the aluminum powder with polyvinyl alcohol. The polyvinyl alcohol-coated aluminum slurry was mixed with a graphene oxide suspension, thereby inducing a reaction between graphene oxide and polyvinyl alcohol via hydrogen bonding. After thermal reduction, the composite powder was further ball milled and hot-pressed at 500℃ to produce a reduced graphene oxide/aluminum composite. The dispersion of reduced graphene oxide in the composite, as well as the mechanical and thermal behaviors of the composite, improved with increased flattening and specific surface area of the starting aluminum powder.

scholarly journals Novel Activated Carbon Nanofibers Composited with Cost-Effective Graphene-Based Materials for Enhanced Adsorption Performance toward Methane

Polymers ◽  
2020 ◽  
Vol 12 (9) ◽  
pp. 2064
Author(s):  
Faten Ermala Che Othman ◽  
Norhaniza Yusof ◽  
Noorfidza Yub Harun ◽  
Muhammad Roil Bilad ◽  
Juhana Jaafar ◽  
...  
Keyword(s):  
Graphene Oxide ◽  
Activated Carbon ◽  
Specific Surface ◽  
Pore Size ◽  
Reduced Graphene Oxide ◽  
Surface Area ◽  
Carbon Nanofibers ◽  
Specific Surface Area ◽  
Activated Carbon Nanofibers ◽  
Reduced Graphene

Various types of activated carbon nanofibers’ (ACNFs) composites have been extensively studied and reported recently due to their extraordinary properties and applications. This study reports the fabrication and assessments of ACNFs incorporated with graphene-based materials, known as gACNFs, via simple electrospinning and subsequent physical activation process. TGA analysis proved graphene-derived rice husk ashes (GRHA)/ACNFs possess twice the carbon yield and thermally stable properties compared to other samples. Raman spectra, XRD, and FTIR analyses explained the chemical structures in all resultant gACNFs samples. The SEM and EDX results revealed the average fiber diameters of the gACNFs, ranging from 250 to 400 nm, and the successful incorporation of both GRHA and reduced graphene oxide (rGO) into the ACNFs’ structures. The results revealed that ACNFs incorporated with GRHA possesses the highest specific surface area (SSA), of 384 m2/g, with high micropore volume, of 0.1580 cm3/g, which is up to 88% of the total pore volume. The GRHA/ACNF was found to be a better adsorbent for CH4 compared to pristine ACNFs and reduced graphene oxide (rGO/ACNF) as it showed sorption up to 66.40 mmol/g at 25 °C and 12 bar. The sorption capacity of the GRHA/ACNF was impressively higher than earlier reported studies on ACNFs and ACNF composites. Interestingly, the CH4 adsorption of all ACNF samples obeyed the pseudo-second-order kinetic model at low pressure (4 bar), indicating the chemisorption behaviors. However, it obeyed the pseudo-first order at higher pressures (8 and 12 bar), indicating the physisorption behaviors. These results correspond to the textural properties that describe that the high adsorption capacity of CH4 at high pressure is mainly dependent upon the specific surface area (SSA), pore size distribution, and the suitable range of pore size.

scholarly journals Effect of Doping Temperatures and Nitrogen Precursors on the Physicochemical, Optical, and Electrical Conductivity Properties of Nitrogen-Doped Reduced Graphene Oxide

Materials ◽  
2019 ◽  
Vol 12 (20) ◽  
pp. 3376 ◽  
Author(s):  
Nonjabulo P. D. Ngidi ◽  
Moses A. Ollengo ◽  
Vincent O. Nyamori
Keyword(s):  
Electrical Conductivity ◽  
Graphene Oxide ◽  
Reduced Graphene Oxide ◽  
Surface Area ◽  
Energy Storage Devices ◽  
Storage Devices ◽  
Nitrogen Doped ◽  
Substitutional Doping ◽  
Reduced Graphene ◽  
Effect Of Doping

The greatest challenge in graphene-based material synthesis is achieving large surface area of high conductivity. Thus, tuning physico-electrochemical properties of these materials is of paramount importance. An even greater problem is to obtain a desired dopant configuration which allows control over device sensitivity and enhanced reproducibility. In this work, substitutional doping of graphene oxide (GO) with nitrogen atoms to induce lattice–structural modification of GO resulted in nitrogen-doped reduced graphene oxide (N-rGO). The effect of doping temperatures and various nitrogen precursors on the physicochemical, optical, and conductivity properties of N-rGO is hereby reported. This was achieved by thermal treating GO with different nitrogen precursors at various doping temperatures. The lowest doping temperature (600 °C) resulted in less thermally stable N-rGO, yet with higher porosity, while the highest doping temperature (800 °C) produced the opposite results. The choice of nitrogen precursors had a significant impact on the atomic percentage of nitrogen in N-rGO. Nitrogen-rich precursor, 4-nitro-ο-phenylenediamine, provided N-rGO with favorable physicochemical properties (larger surface area of 154.02 m2 g−1) with an enhanced electrical conductivity (0.133 S cm−1) property, making it more useful in energy storage devices. Thus, by adjusting the doping temperatures and nitrogen precursors, one can tailor various properties of N-rGO.

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