Fast Diffusion of O2 on Nitrogen-Doped Graphene to Enhance Oxygen Reduction and Its Application for High-Rate Zn-Air Batteries.
Lei-Lei TianJie YangMou-Yi WengRui TanJia-Xin ZhengHai-Biao ChenQuan-Chao ZhuangLi-Ming DaiFeng PanPublished in: ACS applied materials & interfaces (2017)
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 (DE) of oxygen from electrolyte solution to the reactive sites of NDG was evaluated as about 1.5 times the liquid-phase diffusion coefficient (DL) 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.
Keyphrases
- solid state
- ionic liquid
- room temperature
- heavy metals
- highly efficient
- single cell
- metal organic framework
- quantum dots
- carbon nanotubes
- reduced graphene oxide
- gold nanoparticles
- bone marrow
- stem cells
- visible light
- computed tomography
- magnetic resonance
- cell therapy
- mass spectrometry
- density functional theory
- ion batteries
- liquid chromatography