Fibrous Carbon Electrodes Research Articles

Miniaturized 3D printed electrochemical platform with optimized Fibrous carbon electrode for non-interfering hypochlorite sensing.

3D printing technology based electrochemical device can provide ease of fabrication, cost effectiveness, rapid detection and lower limit of detection. Herein, a novel, customized, portable and inexpensive 3D printed electrochemical device, has been presented. Fibrous carbon Toray paper, deposited with gold nanoparticles through electrodeposition, used as a working electrode which Further device was tested with 1mM sodium hypochlorite using cyclic voltammetry (CV) and square wave voltammetry (SWV) in 0.1M PBS. Hypochlorite has a pivotal role in supporting the growing chemical and paper industries and finds diverse uses in several clinical applications. It is primarily used for disinfecting food, water and surfaces. The scan rate study was carried out from 20mVs-1 to 250mVs-1 using cyclic voltammetry technique. The diffusion coefficient obtained from scan rate effect was 1.39×10-6 cm2s-1. The concentration range was evaluated with SWV technique, in a linear range of 0.6μM-40μM, with a detection limit of 0.7μM. The device was further analyzed to ensure non-interference from co-existing chemicals like sodium chloride, potassium nitrate, sodium carbonate, sodium nitrite. Real sample analysis was done with sea, artificial sea and tap water with impressive recovery values. In summary, the developed working electrode can be customized and modified based on testing analyte; thus, the proposed device can be used for various other biochemical analytes.

Electrolysis with Fibrous Carbon Electrodes in Recovery of Platinum Metals from Mineral and Secondary Raw Materials

Electrolytic recovery of platinum metals onto electrodes of fibrous carbon materials from solutions formed by processing of copper–nickel ores, gold- and silver-containing concentrates (gold and silver refining), platinum–rhenium catalysts, and simulated solutions from spent nuclear fuel reprocessing was studied. Combined flowsheets including electrolysis with fibrous carbon electrodes, anodic labilization of platinum metal compounds, extraction, and ion exchange were used. Platinum metals were recovered to low residual concentrations from sulfuric acid, hydrochloric acid, hydrochloric acid + thiourea, ammonia–ammonium, nitric–nitrous acid, and nitric acid solutions. The following processes were used: electrolysis at constant and varied current density, deposition–anodic dissolution, and deposition–dissolution in the short-circuited electrochemical system fibrous carbon material–metal alloy–electrolyte solution. Some processes were successfully trialed on the semicommercial and commercial scales. Trials were performed using semicommercial electrolyzers with fibrous carbon electrodes, developed in cooperation with the special designing bureau of mining and dressing equipment.

Holey Aligned Electrospun Carbon Electrodes for High-Performance Redox Flow Batteries

Recently, the electrospinning method has been employed to fabricate fibrous carbon electrodes in redox flow batteries, due to the large specific surface area of the nano-scale electrospun carbon fibers[1-3]. However, the poor transport properties of the densely packed electrospun carbon electrodes cause a large flow resistance, and hence a large concentration overpotential, which limited the battery’s performances [4,5]. The vanadium redox flow battery (VRFB) is one of the most-studied redox flow battery systems. However, the state-of-art VRFB that employed electrospun carbon fibers as the electrode can only be operated a realtively small current density (~ 100 mA cm-2), which is mainly hindered by the poor transport properties of the electrode material. Hence, the geometric structures of the electrospun carbon materials should be tailored so that the battery with the electrospun carbon fibers can be operated at a much elevated current density with high energy efficiency. Currently, several strategies have been proposed to improve the transport properties of the electrospun material, which include increasing the fiber diameter and expanding the pore sizes. However, the enhancement in the transport properties is always at the cost of sacrificing the active surface area[6].Here we report an approach to effectively enhancing the transport of the electrolyte inside the porous media while ensuring a large specific surface area of the material. Aligned electrospun polymer fiber bundles are successfully produced by properly adjusting the electrospinning conditions. By applying self-etching methods, highly holey aligned fiber bundles were fabricated. In this structure, the aligned large fiber bundles provide the pathway for the electrolyte and the large surface area enabled by the holey fibers provides sufficient active sites for the redox reactions to take place. We compared the single-cell employed with the as-prepared highly holey aligned fibers on both sides with the battery assembled with conventional electrospun materials as well as thermal-treated commercial carbon felts. The results show that the novel structure can enable an energy efficiency of around 79.3% at the current density of 400 mA cm-2.Details of fabricating and characterization of the holey aligned electrospun electrodes and more data relating to the battery tests will be disclosed at the meeting. Acknowledgement The work described in this paper was fully supported by a grant from the Research Grants Council of the Hong Kong Special Administrative Region, China (Project No. T23-601/17-R) References [1] A.D. Blasi, C. Busacca, O.D. Blasi, N. Briguglio, V. Antonucci, Journal of The Electrochemical Society. 165 (2018) A147-A1485.[2] C. Busacca, O. Di Blasi, N. Briguglio, M. Ferraro, V. Antonucci, A. Di Blasi, Electrochimica Acta. 230 (2017) 174-180.[3] A. Di Blasi, C. Busaccaa, O. Di Blasia, N. Briguglioa, G. Squadritoa, V. Antonuccia, Appl.Energy. 190 (2017) 165-171.[4] S. Liu, M. Kok, Y. Kim, J.L. Barton, F.R. Brushett, J. Gostick, Journal of The Electrochemical Society. 164 (2017) A203-A2048.[5] A. Fetyan, I. Derr, M.K. Kayarkatte, J. Langner, D. Bernsmeier, R. Kraehnert, C. Roth, ChemElectroChem. 2 (2015) 2055-2060.[6] C. Xu, X. Li, T. Liu, H. Zhang, RSC Adv. 7 (2017) 45932-45937.

Fibrous electrocatalytic materials based on carbon/copper/copper phosphides for effective hydrogen evolution

The detailed structural analysis of fibrous carbon electrode materials modified by Cu or Cu3P particles is designed for hydrogen evolution reaction (HER). Two different calcination temperatures and reduction atmospheres were used in order to uncover the most effective catalytic electrode material. The novel families of carbon fibrous electrode materials were prepared by low-cost and versatile needle-less electrospinning process. The chemical structure of prepared modified fibers was analyzed by XRD, 13C and 31P NMR spectroscopy. The morphology of the final samples and the location of Cu or Cu3P micro and nanoparticles were observed by SEM and TEM tomography. TEM XEDS mapping revealed the exact position of Cu, P, C and O elements within the matrix of fiber. The electrocatalytic activity for HER was evaluated by the linear sweep voltammetry, impedance spectroscopy and Tafel slopes analysis. The highest performance for HER was observed in the carbon fibers incorporating copper or copper phosphide nanoparticles thermally treated in argon atmosphere at 1000 °C and successively in hydrogen reduction atmosphere.

Removal of fine iron-oxide particles after post-filtration in local potable water using an electrophoretic method

Potable water from several residential areas on the east coast of Malaysia was filtered using a polyethersulphone (PES) membrane to separate the coarse and fine iron-oxide particles inside the pipelines. The as-received samples consisted of a wide distribution of particle sizes, ranging from 5μm to 400nm. The concentration of fine iron-oxide particles inside a distribution system was extremely low. Hence, a specific method is necessary to concentrate and separate the fine particles from the coarse ones. To study the fine particles from the bulk, excess pressure was applied to the membrane filter so that the clogged particles were released into the permeate. A 100kDa PES membrane was used to separate the particles, because the samples consisted of a wide molecular-weight cut-off range from 89g/mol goethite (α-FeOOH) to 231g/mol hematite (Fe2O3). After the filtration process, the size distribution of permeated particles reduced to 550–400nm. Through X-ray diffraction analysis, numerous polymorphs such as α-FeOOH, Fe3O4, Fe2O3 and maghemite were detected from the samples. The zeta potential value of the permeated particles changed from −18.5 to −13mV, suggesting that the dispersity of permeated iron-oxide particles became unstable, but remained adequate for electrophoretic deposition (EPD). The fibrous carbon electrode used in the EPD process, could remove up to 87% of the permeated iron-oxide particles compared to solid carbon electrodes (<56%). A high-surface-area, porous electrode and a moderate applied voltage were preferred in order to minimise gas formation, reduce the electro-osmosis effect and increase the deposition efficiency.

Biomass-derived binderless fibrous carbon electrodes for ultrafast energy storage

Lignin valorization into binderless interconnected and porous carbon fiber electrodes, with excellent performance for supercapacitors, is demonstrated for low-cost, efficient and sustainable energy storage.

Highly Robust Lithium Ion Battery Anodes from Lignin: An Abundant, Renewable, and Low‐Cost Material

The synthesis, processing, and performance of a low‐cost monolithic battery electrode, produced entirely of natural and renewable resources, are reported. This anode material exhibits tunable electrochemical performance suitable for both high power and high energy applications. A synthesis method that directly results in electrically interconnected three‐dimensional architectures is presented, where the carbon framework functions as current collector and lithium insertion material, eliminating the extra mass and expense of inactive materials in conventional designs. Fibrous carbon electrode materials are produced from solvent extracted lignin using scalable melt processing technology and thermal conversion methods. The resulting free‐standing electrodes exhibit comparable electrochemical performance to commercial carbon‐based anodes at a fraction of the materials and processing costs. Compositional and electrochemical characterization shows that carbonized lignin has a disordered nano‐crystalline microstructure. The carbonized mats cycle reversibly in conventional aprotic organic electrolytes with Coulombic efficiencies over 99.9%. Moreover, lignin carbon fibers carbonized at 2000 °C can cycle reversibly in 1 m LiPF6 in propylene carbonate.

Dynamics of copper electrodeposition onto fibrous carbon electrodes with electrical conductivity varying across their thickness

Distribution of copper in its electrodeposition from a sulfuric acid solution onto fibrous carbon electrodes with electrical conductivity varying across their thickness, the deposition rate of copper, and the current efficiency by copper were studied in relation to the electrolysis duration, electrical conductivity of the electrode, geometric current density, and solution flow rate. The main factors governing the distribution of copper across the electrode thickness and the electrolysis parameters beginning from the process onset till the “clogging” of a part of the electrode by the metal were determined.

Dynamics of copper electrodeposition onto fibrous carbon electrodes

Distribution of copper electrodeposited from a sulfuric acid solution onto fibrous carbon electrodes, copper deposition rate, and current efficiency by the metal were studied in relation to the electrolysis duration, electrical conductivity of the electrode, geometric current density, and solution flow rate. The variation of the electrode thickness on which copper ions discharge at the limiting diffusion current at various solution flow rates and the electrode thickness on which the whole amount of oxygen dissolved in the electrolyte is reduced were calculated in relation to the solution flow rate and geometric current density. The main factors governing the distribution of copper across the electrode thickness and the electrolysis parameters from the beginning of the process till “clogging” of a part of the electrode by the metal were determined.

Synthesis of electrolytic manganese dioxide on fibrous carbon electrodes and its use in voltaic cells

Selected problems of electrosynthesis of manganese dioxide, with a fibrous carbon material used as anodes and cathodes, were considered. The quality of the product as a cathode material for managanese dioxide—zinc chemical power cells with an alkaline electrolyte was examined.

Recovery of cadmium and change in properties of a fibrous carbon electrode in electrolytic processing of ammonia washing solutions formed in cadmium plating

The possibility of recovering cadmium deposited on fibrous carbon electrodes from ammonium washing solutions formed in cadmium plating via operation of a short-circuited electrochemical system or anodic dissolution was examined. A polarization study of electrode processes that occur on a renewable graphite microelectrode in ammonium solutions of varied composition was carried out. The change in the properties of fibrous carbon electrodes in their cyclic use in electrodeposition-recovery of cadmium and the possibility of their repeated use were analyzed.

Effect of Cathodic and Anodic Polarization in a Lithium Sulfate Solution on the Electrical Conductivity of Carbonized Fibrous Carbon Materials

The effect of cathodic and anodic polarization of carbonized fibrous carbon materials of the KNM and NT-1 types in a Li2SO4 solution on their properties: electrical conductivity, steady-state electrode potential, electrical conductivity profile across the electrode thickness in relation to the electrolysis time, current density, Li2SO4 concentration, electrode thickness, and current reversal, was studied. The stability of the resulting electrical conductivity profile across the electrode thickness with time and in the course of the subsequent electrolysis was assessed. The reduction of Fe3+ in the ferri-ferrocyanide system on electrically iso- and nonisoconducting fibrous carbon electrode was considered.

Dissolution of Palladium Deposited onto a Fibrous Carbon Cathode in Nitric Acid Solution through Operation of a Short-Circuited Electrochemical System

Dissolution in 3.5 M NHO3 of palladium deposited onto a fibrous carbon electrode from hydrochloric and nitric acid solutions was studied. The factors influencing the dissolution of palladium in contact with the electrode were revealed using a model of short-circuited electrochemical system.

Effect of Anodic Polarization of Fibrous Carbon Electrode in Alkaline and Acid Solutions on the Distribution of Electrical Conductivity across the Electrode Thickness

The effect exerted by anodic treatment of electrodes with varied thickness, made of NT-1 low-conductivity carbonized material, in 0.07 M KOH and 0.25 M H2SO4 solutions on the distribution of the electrical conductivity across the electrode thickness at various anodic polarization conditions was studied.

Characterization and Evaluation of Carbon Fibers as a Negative Electrode of Lithium Secondary Battery

Lithium secondary battery using carbon as negative electrode, where Li is stored, has been developed. In the present paper, various kinds of carbon fibers with different macroscopic and crystallographic structure are applied a negative electrode for the lithium secondary batteries with 1molLiClO4/propylene carbonate electrolyte. And the battery performances of the fibrous electrode are characterized and evaluated as a function of the structural features of the fibers.Li insertion mechanisms into carbon fiber negative electrode are classified into three groups from charge-discharge and the voltammetry measurements. The intercalation takes place in well-ordered graphite fibers, and the doping of Li occurs in the low crystalline, disordered, carbon fibers. Carbon fibers with intermediate crystalline structure indicate voltammograms between well-and disordered carbon fibers. Charge capacities of the fibrous anodes depend upon the crystallinity. Well-ordered and disordered carbon fiber electrodes exhibit larger capacity than those with intermediate crystallinity. It is evidently shown that the crystallinity of the fibrous carbon electrode is an important factor for desig of the cell performances in Li secondary battery.

Removal of cadmium and associated contaminants from aqueous wastes by fibrous carbon electrodes

The electrochemical treatment of aqueous wastes containing 1–20 ppm cadmium, nickel and cyanide was investigated. Graphite felt electrodes were used in flow-by and flow-through type electrochemical cells. The conditions for the simultaneous removal of cadmium and nickel and cadmium and cyanide down to the ppb concentration level were determined. Cell performances were discussed in terms of normalized space velocity. Generally, it was found that the flow-by cell yield is much larger than that of the flow-through cell. However, as the flow velocity decreases, the yields of the two cell types become similar.

Removal of chromium from aqueous solutions by treatment with fibrous carbon electrodes: column effects

The continuous removal of toxichexavalent chromium from contaminated solutions by means of a graphite felt based electrochemical column was studied. The process is based on anin situ generation of appropriate pH gradients which allows both rapid reduction to Cr3+ and its precipitation within the electrode bed. Conditions for the attainment of low (<25 p.p.b.) effluent concentrations as well as longitudinal concentration distribution of the precipitate and maximum loading capacities are presented. Treatment schemes involving two separate columns or a dual function column are also discussed.

The electroadsorption of alumina particles on fibrous carbon and graphite electrodes

The potential dependent adsorption of alumina particles on carbon and graphite fibrous electrodes is studied. Marked differences in the effect of potential on the adsorption rates and saturation capacities among graphite, carbon, and acid-treated carbon electrodes are found. These differences are interpreted in terms of the location of the PZC of each electrode on the potential scale and the charge on the particles. At the open circuit potentials, a maximum in the adsorption rate is observed below the isoelectric pH value. Also, the adsorption rates on the graphite are significantly larger than those on the carbon electrodes. These phenomena are related to the response of the surface groups on the electrodes to pH variations as well as to the stability of the suspension.

Electroadsorption of bacteria on porous carbon and graphite electrodes

The electroadsorption of E. coli and S. typhimurium cells on fibrous carbon electrodes was investigated. Anode-cathode pairs were arranged in series to form a multistage electrofilter through which the bacterial suspension flows in a flow-through mode. Both bacteria species were strongly attached to an electrically charged electrode bed and total removal of bacterial cells was achieved.

Removal of Suspended Alumina Particles from Heavy Water by Electroadsorption on Fibrous Carbon Electrodes

An electrochemical filter is used for efficient and fast removal of alumina particles suspended in heavy water circulating in a nuclear reactor. The process is based on electrostatic interactions between the charged colloids and an oppositely charged porous carbon electrode. A high degree of purification is achieved by this process.