Electrochemical activity and durability of platinum catalysts supported on nanometer-size titanium nitride particles for polymer electrolyte fuel cells

Abstract

We synthesized a Pt catalyst supported on nanometer-size titanium nitride particles (Pt/TiN) by the nanocapsule method. The titanium nitride (TiN) support, which was synthesized by the radio-frequency (RF) plasma method, had high electrical conductivity, up to 850 S cm-1 at room temperature, with a surface area of 40 m2 g-1. The Pt loading on the catalyst was 19.5 wt%. The electrochemically active surface area (ECA) was 72 m2 g(pt)-1. During the potential step cycling test (0.9-1.3 V), the ECA values for Pt/TiN remained high and exceeded that of a commercial Pt catalyst supported on carbon black (Pt/CB) for potential step cycle numbers above 300. From the results of linear sweep voltammetry using a rotating disk electrode, we observed that the oxygen reduction reaction activity of the Pt/TiN exceeded that of Pt/CB. We conclude that the nanometer-size TiN might be a good candidate support material for the cathode of the polymer electrolyte fuel cell (PEFC).