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UPV/EHU-University - More efficient fuel cells for mobile devices(ENP Newswire Via Acquire Media NewsEdge) ENP Newswire - 22 August 2014 Release date- 21082014 - The researcher Noelia Ruiz-Jimenez has managed to optimise the method for spraying the catalyst onto the membrane and improve the carbonaceous medium of the inks, thus achieving greater performance of the catalysts for the fuel cells. This achievement has been accomplished at the Industrial Chemistry and Electrochemical Engineering Laboratory of the UPV/EHU-University of the Basque Country where the researcher Noelia Ruiz-Jimenez wrote up her PhD thesis. The final aim of the research is to enable fuel cells to be used in various portable devices, thus replacing conventional batteries. The starting point of the study by the doctor in Electrochemistry, Science and Technology Noelia-Ruiz-Jimenez has been hydrogen-oxygen fuel cells. Fuel cells are electrochemical devices that turn chemical energy into electrical energy. The ones being studied by this PhD holder use hydrogen and oxygen as fuel: the hydrogen oxidises at the anode and the oxygen is reduced at the cathode to generate electricity. 'Water and heat are the only waste products they produce, so the environmental impact is minimal,' asserted Dr Ruiz. The UPV/EHU's Industrial Chemistry and Electrochemical Engineering Laboratory produces the catalysts used by cells of this type. 'The catalysts we manufacture are characterised by their low level of platinum, so the final price of the single cell is much lower since over half of its cost corresponds to the catalyst. By reducing the amount of platinum used, the final price is cut significantly,' explained Ruiz. In her thesis, this researcher has studied the implementation of the single cell to find out whether catalysts of this type, which have good electrocatalytic behaviour, produce sufficient power in the single cell to enable a portable device to function. 'I confirmed that the electrocatalytic study of the catalyst has nothing to do with its implementation in the single cell, as the single cell is influenced by many parameters that have to be monitored,' said Ruiz. The research team produces a kind of ink with the catalyst: 'A blend of the catalyst itself with carbon, alcohol and an ionomer that acts as a glue so that when the ink is sprayed onto the membrane, it can be properly supported,' explained Ruiz. In fact, the ink is sprayed onto a membrane (a component of the single cell) and depending on its composition and how uniform the spraying is, the cell functions more or less efficiently. Ruiz has taken all these factors into account to study how to implement the catalyst in the single cell, and has confirmed that even though the presence of the platinum is what provides the system with its electro-catalytic properties, the adding of additional metals (co-catalysts) like ruthenium, tin, palladium, rhodium and cobalt improves these properties. 'When these metals are added, there is a bi-catalytic and bifunctional effect on the platinum, thus increasing the catalytic response,' explained Ruiz. She has also confirmed that good chemical activation of the carbon used (Vulcan XC72R) and its subsequent cleaning with nitric acid have played key roles in the good results of her work; at a temperature of 80 *C and 100% relative humidity, a value of 5 W and a mass power value of 16.62 kW g-1 Pt was obtained by using the NiNbPtRu anode catalyst in a 25 cm2 single cell. Dr Ruiz has said she intends 'to use the catalysts developed as batteries for mobile phones or in other portable devices,' if she can obtain sufficient funding. The cells being manufactured in the new line of research use alcohol rather than hydrogen, which gives them added advantages. 'The problem with hydrogen is that it is inflammable; by contrast, alcohols like ethanol and bio-ethanol can be easily handled and, if the battery runs down, it is easier to resort to the latter than to have to plug the device into the mains to charge the battery,' concluded Ruiz. 'The International Journal of Hydrogen Energy' has published various papers relating to this thesis. (c) 2014 Electronic News Publishing - |