g-C3N4– partially unzipped multi-walled carbon nanotubes composites as a metal-free catalyst for the oxygen electrode for alkaline fuel cells

Abstract

A new hybrid composite has been synthesized from partially unzipped multi-walled carbon nanotubes and graphite-like carbon nitride. This composite was thermochemically synthesized from urea and melamine with partially unzipped carbon nanotubes obtained by electrochemical synthesis. The resulting hybrid composite was characterized by X-ray diffraction, selected area electron diffraction, transmission electron microscopy and Fourier-transform infrared and Raman spectroscopy. These methods have proven the production of a hybrid composite of partially unzipped multi-walled carbon nanotubes and graphite-like carbon nitride. As evident from the voltammograms, the hybrid composite material exhibits the highest activity compared to the original components such as g-C₃N₄ and unzipped multi-walled carbon nanotubes. Electrochemical studies have demonstrated that the resulting hybrid composite is a promising material for use as a metal-free catalyst in oxygen electrodes for fuel cells, with performance characteristics approaching those of Pt-based oxygen electrodes. The resulting composites remained stable in operation for six months as an oxygen electrode in a fuel half-cell.