Highly active and stable PdRE catalysts for enhancing electrocatalytic methanol and ethanol oxidation

Abstract

Investigating how rare earth (RE) elements optimize the surface electronic states of noble metal-based electrocatalysts to enhance catalytic activity is of great importance. This study reports the synthesis of PdRE/C (RE = La, Nd, or Dy) catalysts, which are evaluated for the electrocatalytic methanol oxidation reaction (MOR) and the ethanol oxidation reaction (EOR). PdLa/C exhibits superior catalytic activity, with a mass activity (MA) of 2.28 A mg_Pd⁻¹ for the MOR, outperforming PdNd/C, PdDy/C, and commercial Pd/C-JM with a high stability retention of 95.6% after a 4000 s stability test. For the EOR, PdLa/C achieves an MA of 5.67 A mg_Pd⁻¹, 31.5 times higher than that of Pd/C-JM. The results of this study show that RE doping reduced the electronic density of Pd and attenuated CO* adsorption at Pd sites. RE₂O₃ can improve the dispersion of Pd nanoparticles (NPs) and expose much more catalytically active sites. The optimal performance of PdLa/C is attributed to the strongest electronic synergism of Pd–La₂O₃. In addition, in situ Fourier transform infrared (FTIR) shows that PdLa/C enhanced ethanol adsorption/C–C bond cleavage and improved CO₂ selectivity.