Fe-N-C oxygen reduction catalysts supported on vertically aligned carbon nanotubes

Abstract

Abstract Non-noble metal electrocatalyst (Fe-N-C) for the oxygen reduction reaction (ORR) was sputter deposited onto films of vertically aligned carbon nanotubes (VACNT) and tested by the rotating ring disk electrode (RRDE) technique. The VACNT support was first synthesized at atmospheric pressure on a SiO2/Si wafer substrate in a simple tube furnace by iron-catalyzed chemical vapor deposition of ethylene and ammonia at a temperature of 720 °C. VACNT films, with CNT bundle height of 1.5 μm and CNT diameter of 50 nm, were loaded into a sputtering machine to deposit Fe-N-C materials onto the VACNT as support. Iron and carbon were sputtered in a nitrogen atmosphere in order to deposit an amorphous mixture of Fe-N-C material on the VACNT films. The Fe-N-C material supported on the VACNT films was then annealed in Ar at 800 °C to make the ORR electrocatalyst. The catalyst-coated VACNT was scraped off the SiO2/Si substrate and made into catalyst ink for testing by the RRDE technique. The impact of catalyst loading on the RRDE performance (disk current density and %H2O2) is discussed.