Synthesis And Property Of Low Loaded Pt Alloy Catalysts For Oxygen Reduction

In the past decades, study of hydrogen fuel cell drew a lot of attention, indeed this technology could solve the fossil fuel depletion issue and limit the greenhouse effect. Such fuel cells are now widely used in electric cars and for stationary facilities such as emergency generators. Researchers have developed many kinds of fuel cells such as: Proton Exchange Membrane Fuel Cell(PEFMC), Direct Methanol Fuel Cell(DFMC), and Phosphoric Acid Fuel Cell(PAFC). However, this technology is still too expensive to be fully exploited, especially because of its platinum based catalysts which skyrockets the fuel cell’s overall price. Nowadays, researchers focus on a way to enhance catalysis efficiency to solve this issue, but the catalysts produced with a very low platinum rate count today still have few results discussing their design and performances.This study proposes a chemical method to synthesize low platinum catalysts(<10%Wt), based on the hydrothermal alloying method as this process offers high reliability with the possibility of large scale production. An analysis of the different chemical factors and their effects on the final product will be given(reductant, capping agent and solvent). Different alloys’ morphologies will be studied, including octahedral nanoparticles, hollow spheres and an innovative kind of 2D flat sheets. A comparison of the electrocatalytic performances of each sample for oxygen reduction reaction will be carried out by the cyclic voltammetry and linear sweep voltammetry methods. The results obtained in this thesis compared with a commercial Pt/C catalyst, show that in spite of encouraging results the low platinum catalysts do not reach the commercial catalyst efficiency unless the further surface treatment has to be developed to clean and activate surface sites. Moreover, these results give a good base and new interesting shapes with a vast contact surface that need to be optimized to reach a better electro catalytic efficiency.