CO tolerant Pt electrocatalysts for PEM fuel cells with enhanced stability against electrocorrosion
Irina Borbáth, Kristóf Zelenka, Ádám Vass, Zoltán Pászti, Gábor P. Szíjjártó, Zoltán Sebestyén, György Sáfrán, András Tompos
Abstract
An optimized route for preparation of Ti0.8Mo0.2O2–C composite supports for Pt electrocatalysts with 75/25 and 25/75 oxide/carbon mass ratio was elaborated using commercial (BP: Black Pearls 2000) and functionalized (FC) carbon materials. The sol-gel-based synthesis resulted in complete Mo incorporation into the rutile-TiO2 lattice which is a prerequisite for good CO tolerance and high stability. According to the TG and XPS measurements the highest amount of oxygen-containing functional groups was obtained on the BP carbon annealed in nitrogen at 1000 °C and functionalized with HNO3 and glucose. The electrochemical stability tests for 500 polarization cycles performed on the 20 wt% Pt/Ti0.8Mo0.2O2–C catalysts revealed similarly small performance loss (8.5–11.8%) in case of all support materials. Considering the negative effect of the oxide content of the catalyst layer on the cell resistance, the catalyst with Ti0.8Mo0.2O2/C = 25/75 ratio was chosen as the most promising.