Electrochemical synthesis of monodispersed and highly alloyed PtCo nanoparticles with a remarkable durability towards oxygen reduction reaction

PtM (M = transition metals) alloys are currently the most convincing oxygen reduction reaction (ORR) electrocatalysts. Although appealing, uneven particle size distribution inevitably occurs because of large mismatch of reduction thermodynamics and kinetics between Pt and M precursors, and stringent synthetic conditions. An electrodeposition strategy in N, N-Dimethylformamide (DMF) was applied to fabricate PtCo/C electrocatalysts. The coordination between DMF and Pt and Co precursors greatly narrow their deposition potential gap to promote alloying. DMF selectively adsorbs on Pt (111) facets, which helps to expose more PtCo (111) facets to provide a high ORR activity, and greatly benefits the high uniformity of particle sizes to ensure a remarkable durability.The specific activity (SA) of as-optimized PtCo -1.8 /C is more than 5 times that of commercial Pt/C, and shows almost no change after accelerated degradation test (ADT). DFT also indicates that the sample with surface Pt:Co ratio of 1:1 promises the best catalytic activity. A novel DMF-oriented electrodeposition strategy was elaborately proposed to synthesize highly alloyed PtCo nanoparticles with preferred (111) facets as well as monodispersed particle size, all of which result in not only good activity but also remarkable durability for the oxygen reduction reaction (ORR). The synthesis mechanism dominated by coordination and selective adsorption effects of DMF molecules provides a novel thought for preparing heterogeneous catalysts that are difficult to alloyed. • Monodispersed and highly alloyed PtCo/C electrocatalysts were prepared by a direct electrodeposition method in the solvent system of N,N-Dimethylformamide (DMF) • Complexation between DMF and Pt and Co precursors narrows their deposition potential gap thus the alloying degree could be improved • Selective adsorption effect of DMF on (111) facet induces (111) enclosed PtCo nanocrystal formation and benefits the uniformity of particle size • The high alloying degree, monodispersed nanoparticle, closest surface Pt:Co ratio and enriched (111) facets contribute to enhanced activity and stability