Enhanced nitrogen doping in porous carbon and its composite with MnO2 as an efficient oxygen reduction catalyst for Mg–air batteries

• Published in: Journal of materials science Vol. 57; no. 33; pp. 15929 - 15942
• Main Authors: Tachibana, Naoki, Kanai, Minoru, Kamezaki, Yu, Somekawa, Shoichi
• Format: Journal Article
• Language: English
• Published: New York Springer US 01.09.2022; Springer Nature B.V
• Subjects: Air batteries; Annealing; Carbon black; Catalysts; Catalytic activity; Characterization and Evaluation of Materials; Chemical reduction; Chemistry and Materials Science; Classical Mechanics; Crystallography and Scattering Methods; Doping; Energy Materials; Functional groups; High temperature; Hydrogen peroxide; Manganese dioxide; Mass transfer; Materials Science; Maximum power density; Metal air batteries; Nitric acid; Nitrogen; Nitrogen atoms; Oxidation; Oxygen reduction reactions; Polymer Sciences; Solid Mechanics; Synthesis
• ISSN: 0022-2461; 1573-4803
• DOI: 10.1007/s10853-022-07639-1

The objective of this study is to obtain a highly nitrogen-doped carbon with a developed pore network, which can boost mass transfer and provide a large number of active sites for electrocatalytic oxygen reduction. Herein, we synthesized a series of nitrogen-doped carbons in two steps: high-temperature nitric acid treatment of carbon black that effectively introduced oxygen-containing functional groups (oxidation), followed by its annealing with cyanamide that reduced the oxygen-containing functional groups and simultaneously introduced nitrogen atoms (doping). The nitrogen doping level, which depended on the oxygen concentration of the oxidized carbon black, was significantly increased via increasing the oxidation temperature. Furthermore, the annealing step for nitrogen doping increased the mesoporosity of the resultant nitrogen-doped carbons by the formation of void spaces. The highly nitrogen-doped porous carbon synthesized using carbon black oxidized at 80 °C (NPC-80) with high mesoporosity and large surface area exhibited an excellent catalytic activity for the oxygen reduction reaction. The catalytic performance was further enhanced by adding MnO 2 , which can reduce and disproportionate hydrogen peroxide. A Mg–air battery fabricated with the MnO 2 /NPC-80 composite as a catalyst system showed low polarization loss and high maximum power density of 170 mW cm −2 . Graphical abstract