Sputtering and heat treatment of pure Ni metal onto a carbon nanotube on carbon paper to fabricate electrocatalysts for the oxygen reduction reaction in PEMFC

Electrocatalysts were fabricated for a polymer electrolyte membrane fuel cell using a sputter deposition technique. A pure Ni target was deposited onto a carbon nanotube impregnated on carbon paper. The sample was then heat treated in ammonia based environment. In examining the ORR polarization curve and cyclic voltammetry, as the heat treatment temperature changed, the sample showed the highest mass activity at 850 °C. This level of mass activity was 3 times higher than that of samples treated at other temperatures at the same voltage (0.9 V). The optimal heat treatment temperature for maximum mass activity was dependent on the formation of ligands between Ni and CNT which were linked by nitrogen. Even though the catalytic activity is not comparable to that of Pt/C catalysts yet, sputtered Ni based electrocatalysts may potentially serve as the non-precious metal electrocatalysts.

► Ni-electrocatalyst for polymer electrolyte membrane fuel cells.
► Ligand formation between carbon nanotube and Ni.
► Mass activity of Ni-electrocatalyst shows highest value at 850 °C.