Fast Diffusion of O2 on Nitrogen-Doped Graphene to Enhance Oxygen Reduction and Its Application for High-Rate Zn–Air Batteries

• Published in: ACS applied materials & interfaces Vol. 9; no. 8; pp. 7125 - 7130
• Main Authors: Tian, Lei-Lei, Yang, Jie, Weng, Mou-Yi, Tan, Rui, Zheng, Jia-Xin, Chen, Hai-Biao, Zhuang, Quan-Chao, Dai, Li-Ming, Pan, Feng
• Format: Journal Article
• Language: English
• Published: American Chemical Society 01.03.2017
• Subjects: Zn−air battery; oxygen transport; spillover; nitrogen-doped graphene; oxygen reduction reaction
• ISSN: 1944-8244; 1944-8252
• DOI: 10.1021/acsami.6b15235

N-doped graphene (NDG) was investigated for oxygen reduction reaction (ORR) and used as air-electrode catalyst for Zn–air batteries. Electrochemical results revealed a slightly lower kinetic activity but a much larger rate capability for the NDG than commercial 20% Pt/C catalyst. The maximum power density for a Zn-air cell with NDG air cathode reached up to 218 mW cm–2, which is nearly 1.5 times that of its counterpart with the Pt/C (155 mW cm–2). The equivalent diffusion coefficient (D E) of oxygen from electrolyte solution to the reactive sites of NDG was evaluated as about 1.5 times the liquid-phase diffusion coefficient (D L) of oxygen within bulk electrolyte solution. Combined with experiments and ab initio calculations, this seems counterintuitive reverse ORR of NDG versus Pt/C can be rationalized by a spontaneous adsorption and fast solid-state diffusion of O2 on ultralarge graphene surface of NDG to enhance effective ORR on N-doped-catalytic-centers and to achieve high-rate performance for Zn–air batteries.