Enhanced Durability of Pt-Based Electrocatalysts in High-Temperature Polymer Electrolyte Membrane Fuel Cells Using a Graphitic Carbon Nitride Nanosheet Support

摘要

Durability is the main challenge for high-temperature polymer electrolyte membrane fuel cells (HT-PEMFCs). In this study, an electrocatalyst of graphitic carbon nitride (gC(3)N(4)) nanosheet-supported Pt nanoparticles (NPs) is prepared for enhancing the durability of Pt-based electrocatalysts in HT-PEMFCs. Pt NPs are homogeneously dispersed on gC(3)N(4) nanosheets with an average particle size of 1.84 nm. Acid-treated carbon black was introduced to Pt/gC(3)N(4) as a conductive agent to increase the electron-transfer pathways on Pt surfaces, resulting in the Pt/gC(3)N(4)-C electrocatalyst. Electrochemical characterization is carried out with a rotating disk electrode in a 2 mol L-1 H3PO4 electrolyte. After an accelerated durability test of 5000 scanning cycles, the retained electrochemical surface area of Pt/gC(3)N(4)-C is 87.6%, significantly higher than that of commercial Pt/C (54%). Furthermore, a preliminary 100 h durability test is conducted in a practical HT-PEMFC. During the durability test, the voltage decay rate of the membrane electrode assembly (MEA) with commercial Pt/C as the cathode electrocatalyst is 91 mu V h(-1), whereas no obvious drop is observed for the MEA with the prepared Pt/gC(3)N(4)-C as the cathode electrocatalyst. All the results indicate that Pt/gC(3)N(4)-C shows a robust durability compared with commercial Pt/C.