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Studies on the Carbon-supported Pd-based Cathodic Catalysts for Direct Methanol Fuel Cells

Author: ChengLiFeng
Tutor: ZhuLianDe;XuGuoBao
School: Northeast Normal University
Course: Analytical Chemistry
Keywords: Direct methanol fuel cell Oxygen Reduction Electrocatalytic Palladium catalyst Phosphorus Tin
CLC: TM911.4
Type: Master's thesis
Year: 2008
Downloads: 208
Quote: 1
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Abstract


Platinum is the direct methanol fuel cell main catalyst for oxygen reduction materials, but platinum is expensive, resources are very limited, and it has a very low resistance to methanol capacity . Palladium and platinum have similar valence shell structure and lattice constant , relative to platinum , its price is relatively cheap, and reserves are abundant , especially palladium is highly resistant to methanol role, but its catalytic activity to be improved. This palladium catalyst by adding the non-metallic phosphorus and metallic tin to improve the catalytic activity of palladium for oxygen , making it a promising alternative material of platinum . This thesis are as follows: ( 1 ) reduction method using sodium hypophosphite a PdP / C catalyst , the catalyst for the oxygen reduction has high catalytic activity , PdP / C catalyst onset potential and half-wave potentials respectively, compared with Pd / C catalyst is shifted 50mV and 85mV, the limit current ratio Pd / C catalyst is much larger , can achieve commercial Pt / C catalyst level. We denote by physical and chemical methods and electrochemical methods PdP / C catalysts were characterized , the results show that the catalyst for the oxygen reduction catalytic activity due to its small size , relatively low degree of crystallinity and palladium phosphorus alloys formation . The method of non-metallic elements added to improve the catalytic activity of both , and also avoid the metal dissolved. ( 2 ) Reduction using simple impregnation liquid prepared PdSn / C catalyst, tin modification , the catalyst for the oxygen reduction catalytic activity increased. Physical and chemical methods were used and electrochemical methods PdSn / C catalysts were characterized , the results show that the catalyst for the oxygen reduction catalytic activity due to the formation of palladium- tin alloy . On the one hand the addition of tin relative crystallinity of the catalyst decreases the other hand the palladium coating d electrons orbit the center of the negative shift. This was further confirmed by electronic structure theory in the design aspects of the significance of the catalyst .

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CLC: > Industrial Technology > Electrotechnical > Independent power supply technology (direct power) > Chemical power sources,batteries, fuel cells > Fuel cell
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