The mechanism of the improvement in catalytic activity of Ir modified by V compared to pure Ir/C

摘要

The Ir-V/C catalyst was successfully synthesized by EG method as novel, suitable cathode catalyst for PEMFCs. The XRD showed that the interatomic Ir-Ir distances in the Ir-V/C catalyst were decreased, which can result in more facile O_2 adsorption and reduction due to the modified surface and electronic properties. EDS and ICP-MS results indicated that the catalyst contained negligible V content, indicating a beneficial dealloying effect resulting from HC1 addition during catalyst synthesis. With a loading of 0.4 mg_(Ir) cm~(-2) Ir-V/C, it achieved a maximum power density of 517.2 raW cm~(-2), which is higher than the maximum power density of 367.2 mW cm~(-2) obtained for pure Ir/C. In-situ CV results indicated that the loss of the transition metal effectively improved the overall ECSA of Ir-V/C and particle surface roughness of Ir. This provides a higher density of active sites that can adsorb and subsequently reduce oxygen molecules during fuel cell operation.