Pd11Ni11Pt2 nanoparticles with three-phase surface enrichment for facilitating electrooxidation of ethanol and ethylene glycol

Abstract

Rational surface/interface engineering of Pd-based materials plays an extremely important role in boosting the electrooxidation of liquid fuels (e.g. ethanol and ethylene glycol), whereas their complex oxidation process and sluggish kinetics remain formidable challenges for the application of fuel cells. Herein, trimetallic Pd₁₁Ni₁₁Pt₂ nanoparticles with ultrafine size (∼2.19 nm), abundant three-phase surfaces, and strong electronic effects were fabricated to deliver striking electrocatalytic behaviors towards the ethanol oxidation reaction (EOR) and the ethylene glycol oxidation reaction (EGOR) in alkaline media, where Ni and Pt atoms synergistically promoted the electrooxidation reactions through the oxophilic effect and surface modification mechanism, respectively. Remarkably, the mass and specific activities of the Pd₁₁Ni₁₁Pt₂/C catalyst for the EOR are 6461 mA mg_Pd+Pt⁻¹ and 15.32 mA cm⁻², respectively, which are higher than those of the Pd₆Ni₆Pt/C, Pd₅Ni₅Pt/C, PdNi/C, and Pd/C catalysts. Kinetics and thermodynamic analysis indicate that the Pd₁₁Ni₁₁Pt₂/C catalyst is superior to the PdNi/C catalyst in terms of promoting mass transfer, reducing electrochemical activation energy, enhancing electronic conductivity, accelerating charge transfer, and improving anti-CO poisoning ability. Furthermore, in situ Fourier-transform infrared spectroscopy (FTIR) reveals that the PdNi/C and Pd₁₁Ni₁₁Pt₂/C catalysts could electrocatalyze the EOR via both the C1 and C2 pathways, whereas the selectivity of the C1 pathway can be significantly enhanced by incorporating Pt atoms into PdNi/C. Among these catalysts, the Pd₁₁Ni₁₁Pt₂/C catalyst also maintains the highest electrocatalytic EGOR activity and long-term durability. This work not only provides a convenient synthesis strategy for constructing trimetallic Pd-based nanomaterials with ultra-small size and three-phase surfaces, but also provides important guidelines for improving the selectivity of the C1 pathway towards the EOR.