Streamlining of the synthesis process of Pt/carbon xerogel electrocatalysts with high Pt loading for the oxygen reduction reaction in proton exchange membrane fuel cells applications

摘要

Pt/carbon xerogel catalysts were synthesized by different methods. The strong electrostatic adsorption (SEA) method, which consists in enhancing electrostatic interactions between the support and the precursor, was first modified in order to avoid any Pt loss (charge enhanced dry impregnation, CEDI). In a second step, the synthesis was rationalized to speed up the reduction (liquid phase reduction with sodium borohydride, NaBH4). The synthesis procedure was further simplified in order to obtain one-step procedures, such as (i) reduction of highly loaded platinum solution by sodium borohydride, (ii) formic acid reduction, and (iii) colloid synthesis. All the catalysts were analyzed by physicochemical and electrochemical methods. They are compared to a reference commercial catalyst (Tanaka). The best performances are obtained by the SEA, the CEDI and the formic acid reduced catalysts, the performance of which are at least equal to, or even higher (up to 20-25% in mass activity) than those of the commercial reference. From these three methods, the only one-step method is the formic acid reduction, which allows avoiding time-consuming drying and H-2 reduction steps.