Fabrication of VN/TaC Composites with Dual Functions of VN as a Catalyst Support and a Cocatalyst for Improved PEMFC Performance

Tantalum carbide (TaC) was prepared by a salt flux method, and vanadium nitride (VN) and VN/TaC composites (with 2.5, 5.0, and 10.0 wt % VN) were prepared by a sol–gel method. Pt nanoparticles were then deposited uniformly on TaC, VN, and VN/TaC by atomic layer deposition. The performances of these three catalysts for application in proton exchange membrane fuel cells (PEMFCs) were evaluated. It was found that TaC performed better than VN as the catalyst support material, but deposition of VN to form VN/TaC composites would further enhance the performance, presumably because VN could act as a catalyst support and a cocatalyst. With a Pt loading of 0.16 mg/cm2, all the three electrodes of Pt@VN/TaC showed higher maximum specific power densities than that of commercial electrode (Johnson Matthey, JM) when acting as either the anode or the cathode. With the same Pt loading of 0.5 mg/cm2, Pt@2.5% VN/TaC showed higher power density than that of JM when acting as the anode and comparable performance to JM when acting as the cathode. This study demonstrates the dual functions of VN and provides a direction of designing catalyst support materials for PEMFCs.