Journal of Applied Electrochemistry, Vol.46, No.2, 183-189, 2016
Improving the durability of Pt/C catalyst in PEM fuel cell by doping vanadium phosphate oxygen
This study investigated the addition of vanadium phosphate [VO(H2PO4)(2)] to platinum/carbon (Pt/C) to prepare Pt/C-VO(H2PO4)(2) catalyst. Pt/C electrocatalyst was treated with vanadium pentoxide (V2O5) and phosphoric acid concentration to produce VO(H2PO4)(2). This combination improved the durability of proton exchange membrane fuel cells (PEMFCs); nonetheless, the addition of VO(H2PO4)(2) did not negatively affect the homogenization and electrochemical activity of the Pt/C catalyst. Moreover, the presence of VO(H2PO4)(2) was confirmed by the X-ray diffraction pattern and the energy spectrum. The ideal VO(H2PO4)(2) ratio (6 %) was determined, and the VO(H2PO4)(2) was imported to reduce oxidation in the weak acid environment of the PEMFCs cathode catalyst. When the fuel cell operates at high potential, VO2+ is oxidized to VO2 (+). This preferential oxidation protects carbon carriers against oxidation. When the fuel cell returns to normal working potential, the VO2 (+) is restored to VO2+. VO2+ is a reserve for the protection of carbon carriers at the subsequent instance of high potential. The oxide between the Pt particles coated the surface of the carbon carriers, thus limiting the aggregation and loss of Pt. These two functions enhance the durability of fuel cell electrodes.
Keywords:VO(H2PO4)(2);Proton exchange membrane fuel cell;Pt/C catalyst;Hydrothermal method;Redox reaction