• Jarrais, B.
• Guerrero Ruiz, A.
• Rodriguez Ramos, I.
• Freire, Cristina
• Fernandes, Dm
• Novais, Hc
• Haider, A.
• Kortz, U.

Abstract

Regardless of great efforts, the development of novel low cost electrocatalysts with high electrocatalytic activity for the oxygen reduction reaction (ORR) remains a real challenge. This is a setback for the mass commercialization of one of the eco-friendliest alternative power sources: fuel cells (FCs). Thus, this work describes the preparation of four composites based on the 48-tungsto-8-phosphate polyanion salt K28Li5[H7P8W48O184]center dot 92H(2)O (KLi-P8W48) immobilized on four distinct carbon materials, namely graphene flakes (GF), single-walled carbon nanotubes (SWCNT), multi-walled carbon nanotubes (MWCNT), and N-doped multi-walled carbon nanotubes (N-MWCNT), and their application as ORR electrocatalysts. In alkaline medium, all composites exhibited electrocatalytic activity with onset potentials between 0.71 and 0.94 V vs. RHE, while P8W48@N-MWCNT presented superior current density (-3.3 mA cm(-2)). A mixed electron process of 2- and 4-electrons is observed for all the composites, supporting the results of % H2O2 production. Additionally, low Tafel slopes were obtained (43-82 mV dec(-1)) for all composites. The electrocatalysts also showed excellent tolerance to methanol, with current retentions of 91-93%, and good electrochemical stability with current retentions between 67 and 82% after 36,000 s.

Topics

• density
• impedance spectroscopy
• Carbon
• nanotube
• Oxygen
• composite
• current density