Chemically regenerative redox fuel cells (CRRFCs) using liquid catalysts as an alternative to solidstate cathode catalysts have been intensively studied. Here, we studied Fe 2+ /Fe 3+ as a liquid catalyst with Fe-macrocycles as a cocatalyst in CRRFCs. The Fe 2+ -oxidation rate was enhanced in the presence of Fe-Phthanolocyanine. The single cell having the cathode supplied by the liquid catalyst with Fe-Pc showed a maximum power density of ∼249 mW cm −2 .

In this study, we proposed high-performance chemically regenerative redox fuel cells (CRRFCs) using NO /NO with a nitrogen-doped carbon-felt electrode and a chemical regeneration reaction of NO to NO via O . The electrochemical cell using the nitrate reduction to NO at the cathode on the carbon felt and oxidation of H as a fuel at the anode showed a maximal power density of 730 mW cm at 80 °C and twofold higher power density of 512 mW cm at 0.8 V, than the target power density of 250 mW cm at 0.8 V in the H /O 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 HNO .

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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.