Incorporation of multinuclear copper active sites into nitrogen-doped graphene for electrochemical oxygen reduction

Kato, Masaru*; Muto, Marika*; Matsubara, Naohiro*; Uemura, Yohei*; Wakisaka, Yuki*; Yoneuchi, Tsubasa*; Matsumura, Daiju   ; Ishibara, Tomoko*; Tokushima, Takashi*; Noro, Shinichiro*; Takakusagi, Satoru*; Asakura, Kiyotaka*; Yagi, Ichizo*

Multinuclear metal active sites are widely used as catalytic reaction centers in metalloenzymes and generally show high catalytic activity. The oxygen reduction reaction (ORR) is an important reaction not only in oxygenic respiration but also in future energy generation devices such as polymer electrolyte fuel cells and metal-air batteries. Incorporation of multinuclear metal active sites in conductive materials such as carbon will allow us to develop highly active electrocatalysts like metalloenzymes. Herein, we report a copper-based ORR electrocatalyst with multinuclear copper active sites in nitrogen-doped graphene. Electrochemical measurements revealed that the obtained electrocatalyst showed the highest electrocatalytic activity for the ORR in the Cu-based electrocatalysts in neutral aqueous solution. In situ X-ray absorption spectroscopy revealed the incorporation of multinuclear copper sites.