Experimental design of PdFe/G catalysts for oxygen reduction in alcohol fuel cells

PdFe catalysts were prepared to determine the optimal conditions for the oxygen reduction reaction. An experimental design was used. The design included four experimental factors that can influence the final catalyst electroactivity: heating ramp time, catalyst composition, carbon support, and the use of hydrazine during synthesis. The catalysts were synthesized by the polyol method under microwave heating. Heating ramp time and catalyst composition were the most important experimental factors. Compared with the literature, the catalysts performed better and underwent a four-electron reduction process, tolerating the presence of methanol and ethanol. Catalyst composition and heating ramp time influenced nanoparticle size, which ranged from 1.8 to 8.4 nm. EDX results indicated that the metals were well distributed on the support surface. A predictive response surface was obtained, indicating that the Pd₈₂Fe₁₈/G catalyst performed best and that Pd₁₈Fe₈₂/G tolerated ethanol the most. Experimental design proved to be an intuitive tool that helped to understand which changes each experimental factor induced in the catalyst.