High‐Performance Chemically Regenerative Redox Fuel Cells Using a NO3−/NO Regeneration Reaction

In this study, we proposed high‐performance chemically regenerative redox fuel cells (CRRFCs) using NO3−/NO with a nitrogen‐doped carbon‐felt electrode and a chemical regeneration reaction of NO to NO3− via O2. The electrochemical cell using the nitrate reduction to NO at the cathode on the carbon felt and oxidation of H2 as a fuel at the anode showed a maximal power density of 730 mW cm−2 at 80 °C and twofold higher power density of 512 mW cm−2 at 0.8 V, than the target power density of 250 mW cm−2 at 0.8 V in the H2/O2 proton exchange membrane fuel cells (PEMFCs). During the operation of the CRRFCs with the chemical regeneration reactor for 30 days, the CRRFCs maintained 60 % of the initial performance with a regeneration efficiency of about 92.9 % and immediately returned to the initial value when supplied with fresh HNO3. Need to NO: A chemically regenerative redox fuel cell uses the NO3−/NO redox couple as a liquid catalyst at a carbon‐felt cathode. The reduced NO(g) is regenerated to NO3− by O2. It gave a power density of 512 mW cm−2 at 0.8 V, twice the target power density of 250 mW cm−2 at 0.8 V in the H2/O2 proton exchange membrane fuel cells (PEMFCs).