Development of Highly Active and Durable Hybrid Compressive Platinum for Polymer Electrolyte Membrane (PEM) Fuel Cells at USC

摘要

A highly active and stable catalyst/support system is developed by using a two-step process. In the first step, activated carbon composite support (ACCS) is synthesized that retains its activity after accelerated stress test (AST). A 30% Pt/ACCS catalyst shows no loss of mass activity and power density after 5000 cycles at 1.0-1.5 V while the commercial Pt/C and Pt/290G catalysts show drastic mass activity losses (57.5% and 66.2%, respectively) and power density losses (88.7% and 84.0%, respectively). In the second step, compressive Pt lattice (Pt~*) is synthesized through a USC-developed annealing procedure to diffuse Co atoms previously embedded in the support into Pt. The 30% Pt~*/ACCS shows high initial power density (rated) of 0.174 g_(Pt) kW~(-1) and high stability of 24 mV loss at 0.8 A cm~(-2) with an electrochemical surface (ECSA) loss of 42% after 30000 cycles (0.6-1.0 V). A carbon based support is synthesized which is stable under simulated start up/shut-down operating conditions.