The catalytic activities of sputtered cobalt metal electrocatalysts for polymer electrolyte membrane fuel cells

A pure Co metal target was sputtered onto carbon paper and heat treated in an NH3 environment to fabricate Co-based electrocatalysts for the oxygen reduction reaction (ORR) in polymer electrolyte membrane fuel cells (PEMFC). A 100nm-thick Co-based electrocatalyst sample showed the highest current density among the samples examined. It was determined that the optimal level of Co needed to yield content for maximum current density is directly related to the formation of ligands between Co and carbon paper when linked by nitrogen. Unfortunately, lower levels of Co in carbon paper are not able to form sufficient ligands while excessive amounts of Co will in fact hinder the formation of ligands. Although the catalytic activity observed is not comparable to that of Pt/C catalysts yet, sputtered Co-based electrocatalysts show potential as non-precious metal electrocatalysts in fuel cell. ► Sputtering of Co metal onto carbon paper to fabricate Co-based electrocatalysts. ► A 100nm-thick electrocatalyst sample showed the highest current density. ► Proper level of Co in carbon paper is necessary to form sufficient ligands.