Study on the ORR Activity of Platinum-tin Alloy Deposited on Carbon, Porous Carbon and Graphene by Alcohol Reduction Method

• Main Authors: Bing-Jian Su, 蘇竝堅
• Other Authors: Chung-Jen Tseng
• Format: Others
• Language: en_US
• Published: 2018
• Online Access: http://ndltd.ncl.edu.tw/handle/7d36b7

博士 === 國立中央大學 === 機械工程學系 === 106 === Carbon material is widely used today as the catalyst support. In this study, carbon black, ordered porous carbon (OPC), and graphene were used as the catalyst support. The electrocatalysts were synthesized by using alcohol-reduction process and applied for the oxygen reduction reaction (ORR). The physical and morphological properties of the synthesized catalysts were characterized by energy dispersive spectrometer, X-ray diffraction, and high resolution transmission electron microscope. The electrochemical performances were analyzed by cyclic voltammetry, linear scan voltammetry and long-term durability. Results show that samples prepared at pH 12 have smaller particle size than those prepared at pH 9 due to the formation of SnO2 phases in PtSn/C catalysts. When the carbon support was added before the reflux process, the alloy nanoparticles having a size of 4.8 nm are uniformly dispersed on the C support. Although the Pt loading of PtSn12 is only about 75% of the commercial Pt/C, its ORR activity is promoted to 131% due to enhanced catalyst activity and O2 adsorption and dissociation on the catalyst surface. Furthermore, based on the accelerated durability test, the ORR activity after 500 cycles of PtSn12 is 1.34 times higher than that of Pt/C, suggesting that PtSn12 is more chemically stable in the acid environment due to the coexistence of SnO2 in PtSn/C. The Sn12 catalysts have better stability and poisoning tolerance suggesting that SnO2 plays an important role in enhancing the EOR activity and allowing ethanol oxidation to complete. The OPC is fabricated using template method. PtSn is deposited on OPC by the alcohol reduction method. Results show that PtSn/OPC as prepared has well dispersed Pt nanoparticles, with an average particle size around 2.7 nm. The electrochemically active surface area of PtSn/OPC samples is 20% higher than that of commercial E-Tek sample. Furthermore, the long-term stability of Pt/OPC is also better than that of commercial E-Tek sample. The nanoparticles were well-dispersed on the graphene support with an average size of 2.5 nm. The PtSn/G catalyst is more chemically stable in the acid environment than JM Pt/C.