Browsing by Author "Naidoo, Krishnaveni"

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    Testing the suitability of local seaweeds and formulated feed as a food source for abalone (Haliotis midae Linnaeus) in an Integrated Land-based Aquaculture System
    (University of the Western Cape, 2008) Naidoo, Krishnaveni; Maneveldt, Gavin W.; Ruck, Kevin; Dept. of Biodiversity and Conservation Biology; Faculty of Science
    The direct methanol fuel cell or DMFC is emerging as a promising alternative energy source for many applications. Developed and developing countries, through research, are fast seeking a cheap and stable supply of energy for an ever-increasing number of energyconsuming portable devices. The research focus is to have DMFCs meet this need at an affordable cost is problematic. There are means and ways of making this a reality as the DMFC is found to be complementary to secondary batteries when used as a trickle charger, full charger, or in some other hybrid fuel cell combination. The core functioning component is a catalyst containing MEA, where when pure platinum is used, carbon monoxide is the thermodynamic sink and poisons by preventing further reactions at catalytic sites decreasing the life span of the catalyst if the CO is not removed. Research has shown that the bi-functional mechanism of a platinum-ruthenium catalyst is best because methanol dehydrogenates best on platinum and water dehydrogenation is best facilitated on ruthenium. It is also evident that the addition of other metals to that of PtRu/C can make the catalyst more effective and increase the life span even further. In addition to this, my research has attempted to reduce catalyst cost for DMFCs by developing a low-cost manufacturing technique for catalysts, identify potential non-noble metal catalytic systems and develop a basic process to combine various non-noblel, less expensive metallic systems to form binary, ternary and quaternary catalysts. The initial research focused on the identification of a suitable Pt/C preparation method, and characterization of the resulting catalysts by electrochemical methods (including voltammetry), elemental analysis (by EDS), and morphological characterization (by TEM). Once the preparation method for Pt/C had been established, binary (Pt–M/C), ternary (Pt–M1M2 /C) and quaternary (Pt–M1M2M3 /C) catalysts were prepared by modifying the initial Pt/C preparation method. These multi-metallic catalysts primarily function in preventing CO poisoning and allowing MeOH oxidation at the anode. To determine the effectiveness of the in-house multi-metallic catalysts the catalysts were then compared to the commercially available bench mark JM commercially available catalyst. Cyclic voltammetric and chronoamperommetric analysis revealed that the in-house catalysts electrochemical catalytic activity were similair to that of the commercially available catalysts. The Fuel application testing revealed similair trends to that of the EC activity at 0,5V (Ag/AgCl) test results, with the quaternary catalyst proving to be the most active anode catalyst producing the highest power density. The quaternary catalysts proved to be superior with its increased mass activity and high surface area (80% of the catalytic particles < 3nm).