Antiferromagnetic element Mn modified PtCo truncated octahedral nanoparticles with enhanced activity and durability for direct methanol fuel cells

Pt-based magnetic nanocatalysts are one of the most suitable candidates for electrocatalytic materials due to their high electrochemistry activity and retrievability. Unfortunately, the inferior durability prevents them from being scaled-up, limiting their commercial applications. Herein, an antiferromagnetic element Mn was introduced into PtCo nanostructured alloy to synthesize uniform Mn-PtCo truncated octahedral nanoparticles (TONPs) by one-pot method. Our results show that Mn can tune the blocking temperature of Mn-PtCo TONPs due to its antiferromagnetism. At low temperatures, Mn-PtCo TONPs are ferromagnetic, and the coercivity increases gradually with increasing Mn contents. At room temperature, the Mn-PtCo TONPs display superparamagnetic behavior, which is greatly helpful for industrial recycling. Mn doping can not only modify the electronic structure of PtCo TONPs but also enhance electrocatalytic performance for methanol oxidation reaction. The maximum specific activity of Mn-PtCo-3 reaches 8.1 A·m^-2, 3.6 times of commercial Pt/C (2.2 A·m^-2) and 1.4 times of PtCo TONPs (5.6 A·m^-2), respectively. The mass activity decreases by only 30% after 2, 000 cycles, while it is 45% and 99% (nearly inactive) for PtCo TONPs and commercial Pt/C catalysts, respectively.