Oxygen Reduction Reaction of Hemoglobin on Indium-Tin-Oxide Electrodes and Its Application to Biofuel Cell Cathode

摘要

Direct electron transfer characteristics of hemoglobin (Hb) molecules were enhanced on indium-tin oxide (ITO) electrodes synthesized by using a dip-coating solution with a molar ratio of In:Sn = 1:1. The quantity of electrochemically active Hb was estimated to be 222 pmol cm~(-2) from cyclic voltammetry in a pH 7.4 phosphate buffered saline (PBS) solution. In addition, the Hb exhibited oxygen reduction reaction (ORR) activity in O_2 saturated PBS solution at negative potential range from around -0.15 V vs. Ag|AgCl|KCl(satd.). The ORR current reached to 90 μA cm~(-2) at -0.45 V vs. Ag|AgCl|KCl(satd.). A single cell with the O_2|Hb|ITO cathode showed an open circuit voltage of ca. 0.72 V and a maximum power density of ca. 1.1 μW cm~(-2).