A Direct Alcohol Fuel Cell Driven by an Outer Sphere Positive Electrode

Molecular oxygen,
the conventional electron acceptor in fuel cells
poses challenges specific to direct alcohol fuel cells (DAFCs). Due
to the coupling of alcohol dehydrogenation with the scission of oxygen
on the positive electrode during the alcohol crossover, the benchmark
Pt-based air cathode experiences severe competition and depolarization
losses. The necessity of heavy precious metal loading with domains
for alcohol tolerance in the state of the art DAFC cathode is a direct
consequence of this. Although efforts are dedicated to selectively
cleave oxygen, the root of the problem being the inner sphere nature
of either half-cell chemistry is often overlooked. Using an outer
sphere electron acceptor that does not form a bond with the cathode
during redox energy transformation, we effectively decoupled the interfacial
chemistry from parasitic chemistry leading to a DAFC driven by alcohol
passive carbon nanoparticles, with performance metrics ∼8 times
higher than Pt-based DAFC-O2.