Investigation Of Pt/wc/c Catalyst For Methanol Electro-oxidation And Oxygen Electro-reduction

摘要

A Pt/WC/C catalyst is developed to increase the methanol electro-oxidation (MOR) and oxygen electro-reduction (ORR) activities of the Pt/C catalyst. Cyclic voltammetry and CO stripping results show that spill-over of H~+ occurs in Pt/WC/C, and this is confirmed by comparing the desorption area values for H~+ and CO. A significant reduction in the potential of the CO electro-oxidation peak from 0.81 V for Pt/C to 0.68V for Pt/WC/C is observed in CO stripping test results. This indicates that an increase in the activity for CO electro-oxidation is achieved by replacing the carbon support with WC. Preferential deposition of Pt on WC rather than on the carbon support is investigated by complementary analysis of CO stripping, transmission electron microscopy and concentration mapping by energy dispersive spectroscopy. The Pt/WC/C catalyst exhibits a specific activity of 170 mA m~(-2) for MOR. This is 42% higher than that for the Pt/C catalyst, viz., 120 mA m~(-2). The Pt/WC/C catalyst also exhibits a much higher current density for ORR, i.e., 0.87 mA cm~(-2) compared with 0.36 mA cm~(-2) for Pt/C at 0.7 V. In the presence of methanol, the Pt/WC/C catalyst still maintains a higher current density than the Pt/C catalyst.