Effect of the TiO2 phase and loading on oxygen reduction reaction activity of PtCo/C catalysts in proton exchange membrane fuel cells

We investigated the effect of the TiO 2 phase, as either pure rutile (TiO 2 (R)) or a 4 : 1 (w/w) anatase: rutile ratio (TiO 2 (AR)), and the loading on the activity of PtCo/C catalyst in the oxygen reduction reaction (ORR) in a proton exchange membrane (PEM) fuel cell. The incorporation of the different phases and loading of TiO 2 on the PtCo/C catalyst did not affect the alloy properties or the crystalline size of the PtCo/C catalyst, but affected importantly the electrochemical surface area (ESA), conductivity of catalyst layer and the water management ability. The presence of TiO 2 (AR) at appropriate quantity can decrease the mass transport limitation as well as the ohmic resistance of catalyst layer. As a result, the optimum loading of TiO 2 (AR) used to incorporated in the layer of PtCo/C catalyst was 0.06mg/cm 2 . At this content, the TiO 2 (AR)-PtCo/C catalyst provided the highest current density of 438 mA/cm 2 at 0.6V at atmospheric pressure in PEM fuel cell and provided the kinetic current in acid solution of 20.53 mA/cm 2 . In addition, the presence of TiO 2 (AR) did not alter the ORR electron pathway of PtCo/C catalyst. The electron pathway of ORR of TiO 2 (AR)-PtCo/C was still the four-electron pathway.