Enhancement of oxygen reduction reactivity on TiN by tuning the work function via metal doping.

Oxide layers on conductive TiN have recently been investigated to catalyse the oxygen reduction reaction (ORR) in acidic media. The ORR reactivity, i.e., activity and selectivity, has been correlated with the surface nitrogen atoms. A new strategy, optimising the work function via the doping of foreign metals, is revealed herein to enhance the reactivity.

Inexpensive gram scale synthesis of porous Ti4O7 for high performance polymer electrolyte fuel cell electrodes.

As a fuel cell catalyst support, more than 2 g of Magnéli phase Ti4O7 fine-particles were synthesized in a single reaction via an inexpensive route. The single-cell performance reached that of commercial carbon-supported platinum, with an excellent load cycle durability, one of the highest ever reported for oxide-supported platinum catalysts.

Creation of oxygen reduction reaction active sites on titanium oxynitride without increasing the nitrogen doping level.

The oxygen reduction reaction (ORR) active sites on titanium oxynitride (TiOxNy) have been investigated using catalysts with various nitrogen doping levels, leaving some margins to determine their origin. Herein, low-temperature annealing enhanced the ORR activity of carbon-support-free TiOxNy with a constant nitrogen doping level, indicating that oxygen vacancies produced the sites.

Zirconium Oxynitride-Catalyzed Oxygen Reduction Reaction at Polymer Electrolyte Fuel Cell Cathodes.

Most nonplatinum group metal (non-PGM) catalysts for polymer electrolyte fuel cell cathodes have so far been limited to iron(cobalt)/nitrogen/carbon [Fe(Co)/N/C] composites owing to their high activity in both half-cell and single-cell cathode processes. Group IV and V metal oxides, another class of non-PGM catalysts, are stable in acidic media; however, their activities have been mostly evaluated for half-cells, with no single-cell performances comparable to those of Fe/N/C composites reported to date. Herein, we report successful syntheses of zirconium oxynitride catalysts on multiwalled carbon nanotubes, which show the highest oxygen reduction reaction activity among oxide-based catalysts. The single-cell performance of these catalysts reached 10 mA cm-2 at 0.9 V, being comparable to that of state-of-the-art Fe/N/C catalysts. This new record opens up a new pathway for reaching the year 2020 target set by the U.S. Department of Energy, that is, 44 mA cm-2 at 0.9 V.