It is highly desirable for direct alcohol fuel cells to improve the catalytic activity and utilization efficiency of Pt-based electrocatalysts for methanol oxidation reaction (MOR) and ethanol oxidation reaction (EOR). Herein, adding copper salt in precursors has been attempted to tune the morphology, Pt atom distribution, and electronical structures of Pt-based alloy nanoparticles. Furthermore, a heterojunction support formed by polypyrrole (PPy) and carbon black (C) is used to enhance the electron transfer rate from alcohol reactants to electrode as well as the dispersibility of FePtCu nanoparticles on support. Flowerlike FePtCu nanoparticles with an average size of about 53.9 nm are prepared by a high-temperature coreduction method and loaded onto the PPy-C support through the ligand substitute reaction. The as-prepared FePtCu/PPy-C nanocomposite electrocatalyst shows a mass activity of 3.41 A mgPt-1 and a specific activity of 6.13 mA cm-2 for MOR, which are 10.03 and 10.39 times higher than ones of commercial Pt/C catalyst, respectively. Meanwhile, the FePtCu/PPy-C composite electrocatalyst also shows a mass activity of 1.51 A mgPt-1 and a specific activity of 2.72 mA cm-2 for EOR, which are 3.68 and 3.83 times higher than those of commercial Pt/C catalyst, respectively. The electrocatalytic activity of the FePtCu/PPy-C composite for MOR and EOR also exceeded the ones of FePtCu/PPy and FePtCu/C composites significantly, which is highly matched with the structures and electrochemical impedance of materials. Density functional theory simulation for electronic structures reveals the difference of d-band center and intermediates (═CO, OH) adsorption energies of samples, which confirms bifunctional mechanism during electrocatalysis.
Li et al. (Thu,) studied this question.