Pd–MnO2–Fe2O3/C as electrocatalyst for the formic acid electrooxidation

• 18 wt% Pd–MnO2–Fe2O3/C was synthesized via the simple NaBH4 reduction method.
• The synthesized catalyst showed excellent performance upto 3.4 times higher activity than Pd/C.
• The amorphous oxide phases MnO2 and Fe2O3 played a crucial role in improving the activity.

Pd–MnO2–Fe2O3/C and Pd/C (for comparison to the former) were synthesized by NaBH4 reduction method and then annealed at 500 °C. The catalysts were characterized physically by various techniques including XRD, TEM, EDX, XPS and ICP. The results showed that both MnO2 and Fe2O3 are in the amorphous form while Pd is crystalline for both catalysts. The particle size of Pd nanoparticles in Pd–MnO2–Fe2O3/C and Pd/C catalysts were found to be 11.6 nm and 10.9 nm, respectively. The total metal weight percent in Pd–MnO2–Fe2O3/C was determined as 18% and the metal molar ratios of Pd:Mn:Fe was calculated as 49:20:31. By cyclic voltammetry (CV) and chronoamperometry (CA), the ternary catalyst showed a superior electrocatalytic activity, namely of ≈3.4 times higher than Pd/C. The results also indicated that amorphous third parties may play a crucial role to improve the catalyst activity towards formic acid oxidation. All of these results are reported and discussed in details herein.