PtPd catalysts dispersed on coal-based nitrogen-doped carbon nanotubes for formic acid electro-oxidation

Using coal-based polyaniline as a carbon source and nitrogen source, nitrogen-doped carbon nanotubes (NCNTs) were successfully prepared through a two-stage furnace process. The PtPd/NCNTs catalysts were synthesized by the ethylene glycol reduction method. The results of transmission electron microscopy (TEM) show that the PtPd nanoparticles with an averaged diameter of 3.1 ± 0.5 nm uniformly support the surface of NCNTs. The X-ray photoelectron spectroscopy (XPS) reveals that nitrogen mainly exists in graphite states in NCNTs. The electrocatalytic activity of the PtPd/NCNTs catalyst was tested by CO stripping voltammetry, cyclic voltammetry (CV), and chronoamperometry (CA). The electrochemical characterization shows that the PtPd/NCNTs catalyst exhibited higher electrocatalytic activity and stability towards formic acid oxidation. At the same time, its forward peak current density (549.83 mA mg⁻¹) is 4.5 times higher than that of PtPd/CNTs (120.90 mA mg⁻¹). The developed NCNTs are highly promising catalyst supports for direct formic acid fuel cells.