Study of Pt-M (M=Au and Co) nano-catalysts with low Pt loading for PEMFC applications.
Date of Issue2010
School of Chemical and Biomedical Engineering
The research work presented in this thesis is focused on the synthesis of electrocatalysts that contain less amount of platinum but with very high activity for fuel cell reactions to address the scarcity of Pt and its high overpotential during fuel cell operation. Firstly, Ptshell-Aucore electrocatalysts with a controlled shell thickness have been successfully prepared using the successive reduction method. The physicochemical properties have been characterized and their activities have been tested for methanol oxidation reaction. It is found that due to the increase Pt utilization; this structure shows a 3-fold improvement higher than the conventional Pt/C for methanol electrooxidation. Secondly, a novel structure of electrocatalysts, submonolayer Pt-decorated Au nanoparticles with a controlled surface coverage has been successfully prepared and it was found that this novel structure exhibits a remarkably high activity towards formic acid electrooxidation. The origin of the enhancement has been elucidated using electrochemical techniques and it is proposed that this novel structure shows high activity due to the “ensemble” effect and “electronic” effect where the decreasing availability of adjacent Pt atoms this structure posses is responsible for the first effect and the increase in the Pt-d band centre due to adding Au is responsible for the second effect. Moreover, a new reaction mechanism is proposed and the activity-stability-size relation has been studied to optimize the structure and size of this novel structure.
DRNTU::Engineering::Chemical engineering::Biotechnological production