Suddhasatwa Basu

Recent trends in fuel cell science and technology

to Fuel Cells.- Electro-Analytical Techniques in Fuel Cell Research and Development.- Polymer Electrolyte Membrane Fuel Cell.- Fundamentals of Gas Diffusion Layers in PEM Fuel Cells.- Water Problem in PEMFC.- Micro Fuel Cells.- Direct Alcohol and Borohydride Alkaline Fuel Cells.- Phosphoric Acid Fuel Cell Technology.- Carbonate Fuel Cell: Principles and Applications.- Direct Conversion of Coal Derived Carbon in Fuel Cells.- Solid Oxide Fuel Cells: Principles, Designs and State-of-the-Art in Industries.- Materials for Solid Oxide Fuel Cells.- Fuel Cell Power-Conditioning Systems.- Future Directions of Fuel Cell Science and Technology.

Microbial fuel cells for azo dye treatment with electricity generation: a review.

A microbial fuel cell (MFC) has great potential for treating wastewater containing azo dyes for decolourization, and simultaneous production of electricity with the help of microorganisms as biocatalysts. The concept of MFC has been already well established for the production of electricity; however, not much work has been published regarding dye decolourization with simultaneous electricity generation using MFCs. This paper reviews the performance limitations, future prospects, and improvements in technology in terms of commercial viability of azo dye decolourization with electricity generation in MFC. The major limitation identified is the high cost of cathode catalyst. Therefore, there is need of developing inexpensive cathode catalysts. Biocathode is one such option. Moreover, enhanced performance can be obtained by photo-assisted electrochemical process like rutile coated cathode.

Mechanisms for contact angle hysteresis and advancing contact angles

Mixed-wet crude oil/brine/mineral systems typically show a large contact angle hysteresis between the water-receding angle during primary drainage and the water-advancing angle during imbibition. Also, the water-advancing angle may have values that range from 50° to 180°. This investigation uses atomic force microscopy (AFM) to characterize mica surfaces that have first been equilibrated in 0.01 M NaCl, pH 6 brine and then aged in crude oil at elevated temperature. The wettability of the aged surfaces was measured with brine and crude oil. The mica surfaces that were to be examined by AFM were washed with cyclohexane to remove the bulk crude oil. The wettability of the surfaces washed with cyclohexane was measured with brine and decane. Two crude oils were used in this investigation. They were either used as the stock tank oil (STO) or diluted to 40% with n-heptane. This particular dilution was used because it is close to the asphaltene precipitation point of one of the crude oils. The AFM images show the mixed-wet surface to be patches of bare mica and patches of asphaltene with a characteristic areal dimension of about 200 nm. The elevations of the asphaltene patches are about 20 nm for the STOs but increase to above 200 nm when the crude oil is diluted to 40% with n-heptane. These mica surfaces equilibrated with crude oil diluted with heptane have larger advancing contact angles (e.g., 140°) compared to the surfaces equilibrated with STO (e.g., 75°). From this, we infer that the advancing contact angle becomes larger as the asphaltene solvency decreases because of increased coverage of the mica surface with larger asphaltene aggregates.

Dopamine biosensor based on surface functionalized nanostructured nickel oxide platform

A dopamine biosensor has been developed using nickel oxide nanoparticles (NPs) and tyrosinase enzyme conjugate. Nickel oxide (NiO) NPs were synthesized by sol-gel method using anionic surfactant, sodium dodecyl sulphate (SDS), as template to control the size of synthesized nanoparticles. The structural and morphological studies of the prepared NPs were carried out using X-ray diffraction (XRD), transmission electron microscopy (TEM) and dynamic light scattering (DLS) techniques. Afterwards, tyrosinase enzyme molecules were adsorbed on NiO NPs surface and enzyme coated NPs were deposited on indium tin oxide (ITO) coated flexible polyethylene terephthalate (PET) substrate by solution casting method. The formation of enzyme-NPs conjugate was investigated by atomic force microscopy (AFM) and Fourier transform infrared spectroscopy (FTIR) techniques and used in selective detection and estimation of neurochemical dopamine by electrochemical method. The fabricated Tyrosinase/NiO/ITO electrode exhibits high sensitivity of 60.2nA/µM in linear detection range (2-100μM) with a detection limit of 1.038μM. The proposed sensor had a response time of 45s, long shelf life (45 days) with good reproducibility and selectivity in presence of interfering substances and was validated with real samples. The tyrosinase enzyme functionalized NiO platform has good bio-sensing efficacy and can be used in detection of other catecholamines and phenolic neurochemicals.

Hydrogen treated anatase TiO2: a new experimental approach and further insights from theory

Hydrogenated TiO2 (H:TiO2) is intensively investigated due to its improvement in solar absorption, but there are major issues related to its structural, optical and electronic properties and therefore an easily compatible method of preparation is much needed. In order to clarify this issue we studied TiO2 nanocrystals under the partial pressure of hydrogen to modify the structural, optical and electrical properties and to significantly improve the photocatalytic and photoelectrochemical performance. The hydrogen treated TiO2 nanocrystals contained paramagnetic Ti3+ centers and exhibited a higher visible light absorption cross-section as was confirmed by electron paramagnetic resonance diffuse reflectance spectra measurements and X-ray photoelectron spectroscopy. The hydrogen annealed samples showed a noticeable improvement in photocatalytic activity under visible light (λ > 380 nm) which was demonstrated by the degradation of methylene blue dye and an improved photoelectrochemical response in terms of high photocurrent density. Ab initio simulations of TiO2 were performed in order to elucidate the conditions under which localized Ti3+ centres rather than delocalized shallow donor states are created upon the reduction of TiO2. Randomly distributed oxygen vacancies lead to localized deep donor states while the occupation of the oxygen vacancies by atomic hydrogen favours the delocalized shallow donor solution. Furthermore, it was found that localization is stabilized at high defect concentrations and destabilized under external pressures. In those cases where localized Ti3+ states are present, the DFT simulations showed a considerable enhancement of the visible light absorption as well as a pronounced broadening of the localized Ti3+ energy levels with increasing defect concentration.

Microwave-assisted synthesis of porous Mn2O3 nanoballs as bifunctional electrocatalyst for oxygen reduction and evolution reaction

Technological hurdles that still prevent the commercialization of fuel cell technologies necessitate designing low-cost, efficient and non-precious metals. These could serve as alternatives to high-cost Pt-based materials. Herein, a facile and effective microwave-assisted route has been developed to synthesize structurally uniform and electrochemically active pure and transition metal-doped manganese oxide nanoballs (Mn2O3 NBs) for fuel cell applications. The average diameter of pure and doped Mn2O3 NBs was found to be ~610 nm and ~650 nm, respectively, as estimated using transmission electron microscopy (TEM). The nanoparticles possess a good degree of crystallinity as evident from the lattice fringes in high-resolution transmission electron microscopy (HRTEM). The cubic crystal phase was ascertained using X-ray diffraction (XRD). The energy dispersive spectroscopic (EDS) elemental mapping confirms the formation of copper-doped Mn2O3 NBs. The experimental parameter using trioctylphosphine oxide (TOPO) as the chelating agent to control the nanostructure growth has been adequately addressed using scanning electron microscopy (SEM). The solid NBs were formed by the self-assembly of very small Mn2O3 nanoparticles as evident from the SEM image. Moreover, the concentration of TOPO was found to be the key factor whose subtle variation can effectively control the size of the as-prepared Mn2O3 NBs. The cyclic voltammetry and galvanostatic charge/discharge studies demonstrated enhanced electrochemical performance for copper-doped Mn2O3 NBs which is supported by a 5.2 times higher electrochemically active surface area (EASA) in comparison with pure Mn2O3 NBs. Electrochemical investigations indicate that both pure and copper-doped Mn2O3 NBs exhibit a bifunctional catalytic activity toward the four-electron electrochemical reduction as well the evolution of oxygen in alkaline media. Copper doping in Mn2O3 NBs revealed its pronounced impact on the electrocatalytic activity with a high current density for the electrochemical oxygen reduction and evolution reaction. The synthetic approach provides a general platform for fabricating well-defined porous metal oxide nanostructures with prospective applications as low-cost catalysts for alkaline fuel cells.

Statistical analysis on parameters that affect wetting for the crude oil/brine/mica system

Abstract The crude oil properties governing the wettability of crude oil and brine on mica were investigated. Deposition of polar asphaltenes from oil causes mineral wetting to alter from strongly water-wet to less water-wet. The degree of alteration depends on the hydrophobicity of asphaltene and the amount of deposition, which depends on factors such as asphaltene content and solvency of the oil, acid and base content of the oil, brine pH and salinity, aging condition, and mineral type. Physico-chemical properties of the constituent phases that affect mineral wetting were examined. An adhesion test was applied to test water film stability governed by electrostatic interactions between oil/water and water/mineral interfaces. The effect of asphaltene solvency of oil on adhesion was also demonstrated. Statistical analysis was performed on the parameters affecting wettability. When the candidate parameter set was properly chosen, two dominant factors (asphaltene content and base number/acid number) that affect wetting emerge from the analysis. The correlation trend from statistical analysis is consistent with the knowledge and experience obtained from past and current wettability studies.

Effect of calcium ion and montmorillonite clay on bitumen displacement by water on a glass surface

Experiments were conducted to study the effect of calcium ion and montmorillonite clay on bitumen displacement by an aqueous phase on a glass surface. Upon exposure to an aqueous environment containing calcium ion and clays, a thin coating of bitumen on a glass surface displaced spontaneously in the inward radial direction. The initially circular bitumen disk took the shape of a spherical droplet. The dynamic and static contact angles of bitumen on the glass surface were estimated by measuring the contact radius of bitumen with time. The dynamic and static contact angles in the presence of calcium ion and clays are compared with the case when no calcium ion and clays are present. At pH 9, the static contact angle decreased significantly in the presence of calcium ion having a concentration higher than 25 ppm. For a given temperature and at a pH of 9, the initial dynamic angle variation with time was affected less by the presence of clays than with the case of calcium addition. There was no synergetic effect on the dynamic and static angles due to the presence of both calcium ion and clays. In the presence calcium and clays, the results would suggest a negative impact on bitumen liberation from sand grains in the industrial process of bitumen extraction from oil sands. In all cases, the contact angle is measured through the bitumen phase.

Evaluation of an Alkaline Fuel Cell for Multifuel System

The performance of an alkaline fuel cell is investigated using three different fuels, e g., methanol, ethanol and sodium borohydride. Pt/C/Ni was used as anode whereas Mn/C/Ni was used as standard (Electro-Chem-Technic, UK) cathode for all the fuels. Thus, the alkaline fuel cell is used for multi-fuel system. Fresh mixture of electrolyte, potassium hydroxide (5M), and fuel (2M) was fed to and withdrawn from the AFC at a rate of 1 ml/min. The anode was prepared by dispersing platinum and activated carbon in Nafion® (DuPont USA) dispersion and placing it onto a carbon paper (Lydall, USA). Finally prepared anode sheet was pressed onto Ni mesh and sintered to produce the required anode. The maximum power density of 16.5 mW/cm2 is obtained at 28 mA/cm2 of current density for sodium borohydride at 25 °C. Whereas, methanol produces 31.5 mW/cm2 of maximum power density at 44 mA/cm2 of current density at 60 °C.Copyright

In Situ Solid‐State Synthesis of a AgNi/g‐C3N4 Nanocomposite for Enhanced Photoelectrochemical and Photocatalytic Activity

A graphitic carbon nitride (g-C3 N4 ) polymer matrix was embedded with AgNi alloy nanoparticles using a simple and direct in situ solid-state heat treatment method to develop a novel AgNi/g-C3 N4 photocatalyst. The characterization confirms that the AgNi alloy particles are homogeneously distributed throughout the g-C3 N4 matrix. The catalyst shows excellent photoelectrochemical activity for water splitting with a maximum photocurrent density of 1.2 mA cm-2 , which is the highest reported for doped g-C3 N4 . Furthermore, a detailed experimental study of the photocatalytic degradation of Rhodamine B (RhB) dye using doped g-C3 N4 showed the highest reported degradation efficiency of approximately 95 % after 90 min. The electronic conductivity increased upon incorporation of AgNi alloy nanoparticles on g-C3 N4 and the material showed efficient charge carrier separation and transfer characteristics, which are responsible for the enhanced photoelectrochemical and photocatalytic performance under visible light.