A novel Pt/CeO2 catalyst coated with nitrogen-doped carbon with excellent performance for DMFCs

In an attempt to improve the poor electron conductivity of CeO2 as the catalyst support and enhance the activity and long-term durability of the Pt/CeO2 catalyst, a novel catalyst has been developed based on in situ carbonization of ionic liquid to provide an N-doped carbon layer for the Pt/CeO2 catalyst. X-ray diffraction, energy dispersive analysis of X-ray, high resolution transmission electron microscopy, electron energy loss spectroscopy, scanning transmission electron microscopy-energy dispersive spectroscopy elemental mapping, cyclic voltammetry and accelerated aging tests have been performed to characterize the catalyst. The as-prepared Pt/CeO2 catalyst coated with ionic liquid showed significantly enhanced electrochemically active specific surface areas, and superior activity and durability compared to the uncoated Pt/CeO2 catalyst for methanol oxidation, which may be attributed to the reasons as follows: the pyridine-like and pyrrole-like nitrogen with the enhanced pi-bonding in N-doped carbon layers greatly enhance the electrical conductivity of the CeO2 support through a change in the electronic delocalization effect of carbon atoms and a decrease in the loss of electron transfer energy; the surface of the coated CeO2 support contains more active sites for Pt deposition and reduces the surface energy with more uniform Pt dispersion; the lone pair electrons of the N atoms can form a delocalized conjugated system with the sp(2)-hybridized carbon frameworks and strengthen the support-metal interactions; the increase of Lewis basicity of the CeO2 surface results in strong anchoring of Pt to CeO2; the increase of Pt(0) composition during the carbonization of ionic liquid. Different contents of ionic liquid coating the CeO2 support were also investigated and the optimal content is 15 mu L.