C(Mo2C) and Pt–C(Mo2C) based mixed catalysts for oxygen reduction reaction

• The ratio between sp2 and sp3 electronic states is 7:1 in the C matrix.
• The same morphology and structure remained after the modification of C with Pt.
• The cathodic current density peak depends on the amount of added C in the catalyst.
• The mechanism of ORR proceeds through four-electron pathway for mixed catalysts.
• The values of Aeff depend strongly on the composition of the catalyst studied.

The mixed catalysts were prepared by mechanical mixing of the synthesized 60 wt.% Pt–C(Mo2C) (with average Pt nanoparticle size ~ 5 nm) with unmodified carbon powder (synthesized from molybdenum carbide (Mo2C)) to receive the following compositions of the catalysts: 1:1, 1:2, 1:5 60 wt.% Pt–C(Mo2C):C(Mo2C), respectively. The electrochemical characteristics for various micro- and mesoporous carbon based catalysts have been established by cyclic voltammetry and rotating disk electrode methods. Oxygen electroreduction characteristics for the mixed catalysts were compared with the 60 wt.% Pt–C(Mo2C) electrode and with respective 1:1 20 wt.% Pt–C(Mo2C):C(Mo2C) data. Experiments in KOH aqueous solution show that the additionally added carbon powder plays a weak role in Pt–C(Mo2C):C(Mo2C) mixed catalysts increasing the capacitive current densities and shifting the half-wave potential toward more negative values.