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The synthesis of nano tubes based catalyst for electrodes using novel electrode preparation techniques (patent filed) has been formulated, which is expected to be the crucial factor in the performance of the PEM fuel cell. In order to obtain the best efficiency in the cell, the following variables such as i) rates of hydrogen flow from chemical hydrogen generator through the cell, ii) different electrode catalysts materials used, vs voltage/current density produced in the system, iii) temperature vs. the voltage/current density produced in the system, activation, ohmic and concentration polarization are investigated. The performances of PEM fuel cell for vehicle and portable applications are investigated by supplying different hydrogen flow rates by controlling different hydrogen generation rates from chemical hydrogen generator. Direct methanol Fuel cell (DMFC) Pt, PtRu and PtRuM (M = Mo, Ox etc) based catalysts are used as electrode catalysts for DMFC. The catalysts are prepared by impregnation, colloidal and microemulsion methods. Flexible Carbon materials are used as catalyst support. Efforts are being taken for increasing hydrophilicity of the carbon substrate to get better performance of the DMFC. A solution of methanol in water is used as fuel and it is supplied to the anode. Air, oxygen and hydrogen peroxide are used as oxidants. The performance of DMFC is tested with respect to different catalyst, fuel concentrations, electrolytes and catalysts supports. Direct borohydride fuel cell (DBFC) The hydrogen storage alloy, noble metals, Nickel based alloys etc., are investigated as anode catalysts and noble metals are used as cathode catalysts for DBFC. Electrodes are prepared using carbon cloth/paper as substrate for catalyst support. The catalyst is coated using conventional, modern and novel methods (patent filed) and the loading of catalysts are below 1 mg/cm2. Alkaline sodium borohydride solution and other forms of borohydride solutions are used as fuel. The fuel is supplied to the anode with a controlled flow rate. Air, oxygen and hydrogen peroxide etc., are used as oxidents. Solid (Nafion membrane) and liquid electrolytes are used in testing the performance. Polarization studies of DBFC have been studied with respect to different physical and chemical parameters. Microstructure and surface chemistry studies of catalysts have been carried out and correlated with the performance of the DBFC. A well defined catalyst synthesis methodology is being adopted in our laboratory. The catalysts are prepared by impregnation, colloidal and microemulsion methods. Low cost catalysts (particularly for DBFC) with high performance are being synthesized by a novel method (patent filed). Different methodologies of catalyst coating on the substrates are being carried out to enhance the maximum utilization of the catalyst with minimal catalyst loading. Nano binary alloy particles are produced by chemical reduction method. The particle sizes of the catalysts are in the nano meter scale having large surface area and very high porosity. Sodium borohydride (NaBH4) fuel has been extensively studied as a hydrogen storage material because of its advantages of nonflammability and stability in air, easily controlled hydrogen generation rate, recyclable byproduct and high H2 storage efficiency. Hydrolysis of Sodium borohydride (NaBH4) has been extensively studied with different catalysts. Alcoholysis of sodium borohydride (NaBH4) studies have been carried out. The solution generates hydrogen when pumped through a catalyst bed. The reaction side products could then be transported to central facilities for regeneration. The research work focuses on the synthesis of nano particles as catalyst for the hydrogen generator through chemical reduction method. The performance of the hydrogen generator is investigated with different physical (pressure, temperature, flow rate of fuel etc.) and chemical parameters (pH, concentration, etc.). Carbon nano tubes are synthesized to use as substrate for catalyst in all the above fuel cells. Pyrolysis, chemical vapour deposition and flame synthesis techniques are used to synthesis Carbon nano tubes. Single walled and multiwalled carbon nano tubes are obtained with 2 – 100 nm in tube diameters.
Novel electrode for direct borohydride fuel cells, J. C. Ingersoll and N. Mani communicated to Journal of Power Sources Catalytic hydrolysis of sodium borohydride by a novel nickel–cobalt–boride catalyst, J.C. Ingersoll , N. Mani, J.C. Thenmozhiyal and A. Muthaiah, Journal of Power Sources 173 (2007) 450-457. Published from IIT madras
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