High Power Density of a Hydrogen Peroxide Fuel Cell Using Cobalt Chlorin Complex Supported on Carbon Nanotubes as a...

Hydrogen peroxide fuel cells (HPFCs) have attracted much attention due to their simple one-compartment structures and high availability under harsh conditions such as an anaerobic environment; however, catalysis improvement is strongly demanded for both anodes and cathodes in terms of activity and durability. Herein, we report the high catalytic activity of Co^II chlorin [Co^II(Ch)] for hydrogen peroxide (H₂O₂) oxidation with a low overpotential (0.21 V) compared to that of the Co^II phthalocyanine and Co^II porphyrin complexes, which have previously been reported as active anode catalysts. Linear sweep voltammograms and differential pulse voltammograms of the Co^II complexes (Co^IIL) and the corresponding ligands clearly showed that the Co^IIIL species are the active species for H₂O₂ oxidation. Then, one-compartment HPFCs were constructed with Co^II(Ch) supported on multiwalled carbon nanotubes (CNTs) as the anode together with Fe^II₃[Co^III(CN)₆]₂ supported on CNTs as the cathode. The maximum power density of the HPFCs reached 151 μW cm^-2 with an open circuit potential of 0.33 V when the coverage of CNT surfaces with Co^II(Ch) exceeded ∼60% at the anode.