Alloying with Mn Enhances the Activity and Durability of the CoPt Catalyst toward the Methanol Oxidation Reaction.

To improve the catalytic performance and durability of Pt catalysts used for the methanol oxidation reaction (MOR) in direct methanol fuel cells (DMFCs), alloying of Pt with other transition metals such as Ru, Co, Ni, and Fe is considered an effective approach. Despite the significant progress made in the preparation of bimetallic alloys and their utilization for MOR, improving the activity and durability of the catalysts to make them commercially viable remains a stiff challenge. In this work, trimetallic Pt 100- x (MnCo) x (16 < x < 41) catalysts were successfully synthesized via borohydride reduction followed by hydrothermal treatment at 150 °C. The electrocatalytic performance of the synthesized trimetallic Pt 100- x (MnCo) x (16 < x < 41) catalysts toward MOR was studied using cyclic voltammetry and chronoamperometry. The results affirm that all Pt 100- x (MnCo) x (16 < x < 41) alloys have superior MOR activity and durability as compared to bimetallic PtCo alloys and commercially available Pt/C (comm. Pt/C) catalysts. Among all the compositions studied, the Pt 60 Mn 1.7 Co 38.3 /C catalyst exhibited superior mass activity (1.3 and 1.9 times higher than those of Pt 81 Co 19 /C and comm. Pt/C, respectively) toward MOR. Furthermore, all the newly synthesized Pt 100- x (MnCo) x /C (16 < x < 41) catalysts showed better CO tolerance when compared with comm. Pt/C. This improved performance of the Pt 100- x (MnCo) x /C (16 < x < 41) catalyst can be attributed to the synergistic effect of Co and Mn on the Pt lattice.