Linking Structure to Electrocatalytic Performance: Graphene Nanoplatelets-Derived Novel Mixed Oxide–Carbon Composites as Supports for Pt Electrocatalysts with Enhanced Stability

The lifetime of polymer electrolyte membrane fuel cells (PEMFCs) is significantly influenced by the degradation of their catalysts. A composite-type electrocatalyst support with the formula Ti_(1-x)Mo_xO₂-C (x: 0-0.2, C: carbon) has been found to provide higher stability for the Pt active metal than carbon alone. Non-traditional carbon materials such as graphene nanoplatelets (GNPs) and graphite oxide (GO) offer new possibilities for supports. This work aims to explore whether it is possible to combine the advantageous properties of GNP and GO in composite-supported Pt electrocatalysts. Composites prepared using the modified sol-gel method and Pt catalysts supported on them were characterized by physicochemical methods. Electrochemical behavior in terms of CO tolerance, activity and stability was studied. Although GO transformed into a mainly graphitic material during composite synthesis, its addition still increased the functional group content of the carbonaceous backbone. The electrical conductivity was significantly higher when GNPs-GO mixtures were used as the starting carbon material compared to the use of pure GNPs. Increased CO oxidation activity was achieved due to the incorporated Mo. Stability of the composite-supported Pt catalyst was significantly higher than that of commercial Pt/C. Increased stability of the GNPs-GO-derived catalyst compared to the GNP-derived one was obtained.