Numerical Modeling of Cyclic Voltametry

This paper deals with a new approach to numerical modeling of cyclic voltammetry using the CFD solver FLUENT. The standard use of this solver is in the field of flow and heat transfer calculations, however, it is possible to model electrochemical reactions and it also includes basic models for calculations related to batteries, such as charging and discharging processes, temperature fields, etc. Thanks to the possibility of scripting, however, it is possible to extend these tasks to a much more complex level.

SYNTHESIS THIN FILM ELECTRODES GRAPHENE VIA NOVEL 3D PRINTALBE TECHNIQUE AND DETERMINE PROPERTY ELECTROCHEMICAL

Graphene film electrodes have many important applications, but the fabriacion of these electrodes is difficult dues to the poor processing of graphene. This article describes the preliminary results of using 3D printing technology to fabricate thin-film electrodes from graphene oxide inks. Graphene oxide ink is synthesized by chemical method. The graphene oxide (GO) and reduction graphene oxide (r GO) thin film were chacracterized by filed scanning electron microscopy (FESEM) and Energy-dispersive X-ray spectrocopy (EDX spectrocopy) to make sure the morphological and optical characteristics of the thin film. In addition, the electrochemical aera active studies were also determined by cyclic voltametry (CV) curves. The r GO thin film displays higher electrochemical area active in comparison with GO, which is 2.56 cm2 compare to 0.31 cm2, indicating the best result for the superior conductivity of thin film electrode.

Activated Carbons (AC) Prepared by Direct CO2 Activation of Parsea Americana seeds Biomass for Supercapacitor Electrodes

Biomass converted into activated carbon (AC) by using physical activation method can form micro-meso pore structure and maintain the interconnected natural pore network of biomass. AC is prepared from the biomass of Parsea Americana seeds (PAS) through a process of pre-carbonization, chemical activation, carbonization and physical activation which is activated at temperatures of 700°C, 800°C, and 900°C. Characterization of physical properties of AC electrodes consisted of X-ray diffraction, Scanning Electron Microscope-Energy Dispersive X-ray and characterization of electrochemical properties of supercapacitor cells using Cyclic Voltametry. The results showed that the microstructure of the AC electrode has a semicrystalline structure characterized by the presence of two sloping peaks at an angle of 2θ around 24° and 44° which corresponded to the hkl (002) and (100) planes, where the lowest Lc value was produced by the PAS-900 sample. The PAS-900 sample had aggregates or lumps with smaller size in small amounts in the presence of micro-mesopores and had the highest carbon content of 94.50% with the highest capacitance value of 203.12 F/g. The temperature of 900°C is the best activation temperature in the process of manufacture AC electrodes from Parsea Americana seeds biomass for supercapacitor cell applications.

Nanopatterning Graphite Surface by Diazoniums Using Electrochemical Method

Molecular functionalization of graphitic surfaces with nanopatterned structures is regarded as one of the effective bottom-up techniques to tune their electronic properties towards electronics applications. Diazonium molecules have been often employed to covalently functionalize graphene and highly oriented pyrolytic graphite (HOPG) substrates. However, controlling the structure of the molecular adlayers is still challenging. In this contribution, we demonstrated an inconventional approach for covalent functionalization the HOPG surface by using mixture of 4-nitrobenzenediazonium (4-NBD) and 3,5-bis-tert-butylbenzenediazonium (3,5-TBD) molecules in which the former tends to polimezise and physisorb while the later chemically anchors on surface. The physisorbed features can be removed by washing with hot toluene and water. As a result, the HOPG surface is patterned in a quasi-periodic fashion. The efficiency of this development was verified by a combination of cyclic voltametry (CV) and atomic force microscopy (AFM) methods. This finding represents a convenient strategy for creating nanoconfined templates that might serve as nano-playgrounds for further supramolecular self-assembly and other on-surface reactions.

Synthesis of activated carbon electrodes from date seeds with a variety of separators for supercapacitor cell applications

Abstrak. Karbon aktif yang berasal dari biomassa telah menjadi bahan elektroda paling kompetitif untuk superkapasitor karena sifatnya yang terbarukan dan berkelanjutan. Upaya optimalisasi dilakukan untuk proses pembuatan sel superkapasitor dengan memvariasikan separator agar dapat memperoleh kapasitansi spesifik yang tinggi. Biomassa biji kurma sebagai bahan dasar pembuatan elektroda karbon melalui proses prakarbonisasi, aktivasi kimia dengan aktivator KOH 0,3M, proses karbonisasi dengan suhu 650oC dialiri gas nitrogen. Penyusutan massa karbon sebesar 24,59%. Nilai densitas dari elektroda karbon setelah dilakukan proses karbonisasi adalah 0,852 g cm-3. Analisis struktur mikro menunjukkan bahwa elektroda karbon bersifat amorf ditunjukkan dengan adanya puncak pada sudut 2θ sekitar 24o dan 44o. Kapasitansi spesifik ditentukan dengan metode Cyclic Voltametry dan didapati sebesar 217,22; 176,18; dan 82,8 F/g masing-masing untuk variasi separator kertas whatman, kertas saring, dan membran telur ayam. Hasil penelitian menunjukkan bahwa pada kertas whatman merupakan separator terbaik untuk elektroda karbon dari biji kurma. Oleh karena itu karbon aktif yang dibuat dari biji kurma dengan biaya rendah, ketersedian mudah, dan berkelanjutan dapat diaplikasikan sebagai bahan elektroda untuk superkapasitor.Abstract. Activated carbon derived from biomass has become the most competitive electrode material for supercapacitors due to its renewable and sustainable nature. Optimization efforts are made for the process of making supercapacitor cells by varying the separator in order to obtain a high specific capacitance. Date seed biomass as the basic material for making carbon electrodes through a pre-carbonization process, chemical activation with a KOH activator of 0.3M, the carbonization process at a temperature of 650oC flowed with nitrogen gas. Shrinkage of carbon by 24.59%. The density value of the carbon electrode that was carried out by the carbonization process was 0.852 g.cm-3. The microstructure analysis showed that the carbon electrode was amorphous indicated by the presence of a peak at an angle of 2θ around 24o and 44o. Specific capacitance was determined by the Cyclic Voltametry method and was found to be 217.22, 176.18, and 82.8 F/g respectively for the Whatman paper, filter paper, and chicken egg membrane separator variations. The results showed that whatman paper was the best separator for carbon electrodes from date palm seeds. Therefore, activated carbon made from date seeds with low cost, easy availability, and sustainability can be applied as an electrode material for supercapacitors.Keywords: Date seed, Activated Carbon, Supercapacitor, Carbon Electrode, Separator

Processing of Iridium Doped Materials and Experimental Investigation of Their Hydrogen Adsorption Capacity

The paper aims to present the investigation of H2 adsorption capacity in metal doped nanostructured materials, by using two methods. Carbonic materials are considered to be one of the most promising materials to be used for hydrogen adsorption and storage. They have different applications and one of the most important is considered to be fuel cells technology. By using metals for doping these materials, the adsorption capacity increases, thus approaching the target of 6.5% weight ratio of H2 adsorbed in a substrate. Within these investigations multi-wall nanotubes and poly-aniline have been used as substrates. The poly-aniline has been prepared and doped in laboratory while the nanotubes used in experiments have been purchased from the market and afterwards doped in laboratory. The doping procedure consists of a physical-chemical method which involves salts of the metal for doping and the use of ultrasounds in order to activate the substrate for doping. The adsorption capacity of the carbonic materials has been determined by using spill over phenomena in a PCT Pro-User apparatus, provided by SETARAM and also by cyclic voltametry, by using VoltaLab-40 apparatus. In order to investigate the adsorption capacity of the nanostructured carbonic materials, the experiments have been carried out at different pressures. Both substrates have been characterized in order to determine their porosity, BET surface and structure. The collected data have been processed by using the PCT Pro-User apparatus�s software. The results have been compared with the available data from literature and a good consistency was found.

STUDI SIFAT ELEKTROKIMIA SEL BATERAI SEKUNDER POUCHCELL LITHIUM ION LIFEPO4/GRAPHITE APLIKASI DAYA TINGGI

Abstrak Telah dilakukan pembuatan lembaran katoda dari serbuk LiFePO4 komersial dan anoda dari serbuk Graphite. Lembaran difabrikasi membentuk sel penuh baterai dengan tipe sampel uji berbentuk Pouchcell. Konfigurasi sel adalah LiFePO4//LiPF6//graphite, LiPF6 digunakan sebagai elektrolit cair. Karakterisasi sel dilakukan meliputi uji cyclic voltrametry, charge discharge dan EIS (electrochemical Impedance Spectroscopy. Nilai yg dihasilkan adalah kapasitas mencapai sekitar 80 mAh/gr, dengan tegangan Voc stabil pada nilai 3.28 V. Nilai discharge capacity yang bisa diambil hingga 5C lebih dari 40%, dengan life cycle pada 50 siklus kehilangan kapasitas hanya kurang dari 5%. Kata-kata kunci: pouchcell, cyclic voltametry, electrochemical impedance spectroscopy, baterai high power. Abstract In this work, have been fabricated cathode electrode from LiFePO4 powder and anode from commercial Graphite powder. Full cell batteries fabricated in Pouchcell shaped test samples. Lithium ion cell configuration are LiFePO4 // LiPF6 // graphite, 1 M LiPF6 in EC/DEC is used as the liquid electrolyte. Cell batteries Perfomance characterized by some tests conducted on the cyclic voltrametry, charge-discharge and EIS (electrochemical impedance spectroscopy. The result value are the capacity reached approximately 80 mAh / g, with the voltage Voc perfectly stable at 3.28 V. The discharged capacity can be taken up to 5C almost over 40% , with after 50 cycles for life cycle test the capacity loss is retain still 95% at 0.33C. Keywords: pouchcell, cyclic voltametry, electrochemical impedance spectroscopy, high power battery.

Electrofabrication of Ni-Co-CNT Composite Coatings for Hydrogen Energy

The present study reports the enhanced electrocatalytic activity of Ni-Co alloy coatings due to addition of known quantity of carbon nanotube (CNT) into the bath. The Ni-Co-CNT composite coatings were electrodeposited on copper substrate from a sulphate bath, using glycerol as the additive. Electrocatalytic efficiency of the coatings, used as electrodes were tested for both Hydrogen evolution reaction (HER) and Oxygen evolution reaction (OER) in 1M KOH using cyclic voltametry and chronopotentiometric techniques. The experimental conditions were optimized to maximize the electrocatalytic activity of both Ni-Co and Ni-Co-CNT coatings for HER and OER. The experimental results revealed that Ni-Co-CNT coatings deposited at high current densities are more favorable for OER and HER, compared to bare Ni-Co coatings deposited from same bath, under same condition. The substantial improvement in the electrocatalytic activity of Ni-Co-CNT composite coatings was attributed to increased porosity due to addition of CNT. The structure-property relationship of both Ni-Co and Ni-Co-CNT alloy coatings for HER and OER were used to explain the role of CNT in enhancing electrocatalytic activity, with the support of XRD, SEM and EDX analyses.