One-pot synthesis of platinum-samarium dendritic nanocrystals with tunable elemental compositions for efficient electrocatalytic methanol oxidation via f-d hybridization interaction

Abstract

Metallic doping is widely recognized as an effective approach to modulate the intrinsic electronic structure of platinum (Pt)-based electrocatalysts, thereby enhancing their performance in fuel cells. Recent progress mainly focused on doping metals from d-block or p-block of the periodic table to promote d-d or p-d hybridization interactions, while f-block metals, such as rare earth metals, have received less attention. In this study, samarium (Sm)-doped Pt nanocrystals with a dendritic nanoparticle morphology were synthesized with precise control over their elemental composition. The key to achieving this unique morphology was the co-reduction of halide-free Pt and Sm precursors by glucose in the presence of cetyltrimethylammonium chloride (CTAC) in N-oleyl-1,3-propyldiamine (OPDA) at an elevated temperature. When employed as an electrocatalyst for the methanol oxidation reaction (MOR) in an alkaline medium, the optimized Pt86.4Sm13.6 nanodendrites/C exhibited nearly a 7-fold increase in specific activity, accelerated reaction kinetics, and enhanced long-term durability compared to commercial Pt/C. This improved electrocatalytic activity is attributed to the unconventional f–d hybridization interactions, which weaken CO binding and reduce the CO poisoning effect. The f-d hybridization interactions were further elucidated by density functional theory (DFT) calculations, which showed that the stronger interaction between OH and Sm-doped Pt(111) surface exhibits a benefit to combine with CO to form COOH and then release CO2, affirming the critical role of Sm-doping in improving the MOR activity. This research offers a viable strategy for creating rare earth metal-doped bimetallic nanocrystals with controlled morphology and may be extended to the rational design of high-performance fuel cell electrocatalysts based on f-d orbital hybridization.