Synthesis of carbon microspheres from urea formaldehyde resin

Carbon microspheres were synthesized through polymerization of urea/formaldehyde in the presence of formic acid as catalyst, followed by drying and carbonization in an inert atmosphere. The samples were characterized by SEM, XRD, HRTEM, elemental analysis and XPS. The obtained carbon microspheres were amorphous indicated by the results of XRD and HRTEM. The changes of nitrogen functionalities at 400–1000 °C were determined by XPS. The fraction of pyridine nitrogen and pyrrole/pyridone nitrogen decreased with increasing temperature, whereas the amount of quaternary nitrogen increased.