Fast Diffusion of O2on Nitrogen-Doped Graphene to Enhance Oxygen Reduction and Its Application for High-Rate Zn-Air Batteries.
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 O2on ultralarge graphene surface of NDG to enhance effective ORR on N-doped-catalytic-centers and to achieve high-rate performance for Zn-air batteries.
School of Advanced Materials, Shenzhen Graduate School, Peking University , Shenzhen 518055, China.
Lei-Lei
LL
Tian
School of Advanced Materials, Shenzhen Graduate School, Peking University , Shenzhen 518055, China.
Jie
J
Yang
School of Advanced Materials, Shenzhen Graduate School, Peking University , Shenzhen 518055, China.
Mou-Yi
MY
Weng
School of Advanced Materials, Shenzhen Graduate School, Peking University , Shenzhen 518055, China.
Rui
R
Tan
School of Advanced Materials, Shenzhen Graduate School, Peking University , Shenzhen 518055, China.
Jia-Xin
JX
Zheng
School of Advanced Materials, Shenzhen Graduate School, Peking University , Shenzhen 518055, China.
Hai-Biao
HB
Chen
School of Materials Science and Engineering, China University of Mining & Technology , Xuzhou 221116, China.
Quan-Chao
QC
Zhuang
Department of Macromolecular Science and Engineering, Case Western Reserve University , 10900 Euclid Avenue, Cleveland, Ohio 44106, United States.
Li-Ming
LM
Dai
School of Advanced Materials, Shenzhen Graduate School, Peking University , Shenzhen 518055, China.
Feng
http://orcid.org/0000-0002-8216-1339
F
Pan
Zn−air battery; nitrogen-doped graphene; oxygen reduction reaction; oxygen transport; spillover