Catalase-Based Air-Cathode for Biocompatible Zinc–Air Battery

The use of catalase (CAT) from bovine liver as an electrocatalyst in the air electrode of a primary zinc–air battery (ZAB) with neutral electrolyte (pH 7.4) is reported. First, the use of Nafion for immobilizing CAT onto electrode surface allowed to obtain long-term stability of the catalytic activity of CAT. Besides, analysis of the CAT and CAT-Nafion as catalysts for oxygen reduction reaction (ORR) was carried out by linear sweep voltammetry (LSV) using a rotating ring-disk electrode (RRDE), demonstrating a four-electron ORR mechanism. Finally, CAT and CAT-Nafion were tested as air electrodes in flooded ZAB and compared against human hemoglobin-based ZAB. Our results demonstrated the significant influence of the protein coating of the heme groups on the ZAB performance, affecting greatly the discharge capacity and the power density.