Electrochemical characterization and durability of sputtered pt catalysts on TiO₂ nanotube arrays as a cathode material for PEFCs

In the present study, we describe an approach to address both the catalytic activity and the durability issues synergistically for polymer electrolyte fuel cells (PEFCs) by using robust TiO₂ nanotube (TONT) arrays as an alternative support to replace carbon. We formed sputtered Pt on TONT arrays, which were prepared by the electrochemical anodizing procedure, and evaluated the resulting catalysts for oxygen reduction reaction (ORR) kinetics and for accelerated durability tests (ADTs). The high ORR activity of the Pt/TONT catalyst is attributed to a synergistic effect between Pt and TONT and to the increase in electrochemical active surface area. Kinetic analysis reveals that the number of electrons for the Pt/TONT catalyst is ca 3.94, which indicates a preferential four-electron transfer reaction. Moreover, the ADT result for the Pt/TONT catalyst shows a small decrease in the Pt active surface, which is attributed to the strong and stabilized physical interaction between the Pt catalyst and the TONT support. A strong metal-support interaction effect may prevent the agglomeration and dissolution of Pt catalysts on the TONT support, thereby producing a catalyst with an extended life.