Development of High Durable Catalyst for PEFC

PEFC is focused as highly efficiency and clean energy device to reduce emission of CO2. Pt/C and PtCo/C are widely used as cathode electrocatalyst for PEFC. But there are many issues required for catalyst such as low platinum and high durability for the widespread use of PEFC. We tried to improve catalyst durability against potential cycles attributed to Pt dissolution. We prepared barrier layer on the Pt/C cathode catalyst surface to prevent the increasing in particle size due to Pt dissolution and reprecipitation. The ORR mass activity at 0.90V and electrochemical surface area (ECSA) of catalysts were measured by 25cm2-MEA. Durability evaluation was carried out by conducting potential cycles of 650mV-1050mV attributed to Pt dissolution and measuring the activity every constant potential cycles. Fig.1 shows mass activity and ECSA of standard Pt/C and improved Pt/C catalyst with potential cycles. ORR mass activity and ECSA of Pt/C catalyst was significantly decreased after cycles. It seems that the dissolution of Pt remarkably progressed. On the other hand, decreasing in mass activity and ECSA of improved-Pt/C catalyst with barrier layer was significantly suppressed compared to Pt/C catalyst. It was shown that decreasing in surface area due to dissolution and reprecipitation of Pt would be prevented and high activity was maintained even after potential cycles by barrier layer. To understand Pt dissolution phenomenon of each catalysts, we investigated the MEA after the durability test by TEM and EPMA analysis. From analysis results, increasing in particle size and Pt band formation of improved Pt/C catalyst were significantly suppressed after durability test compared to standard Pt/C catalyst. These results suggest that barrier layer on the catalyst surface is much effective for improving catalyst durability against potential cycles. Figure 1