title: Cobalt-embedded nitrogen doped carbon nanotubes: a bifunctional catalyst for oxygen electrode reactions in a wide pH range.
abstract: Electrocatalysts for the oxygen reduction and evolution reactions (ORR/OER) are often functionally separated, meaning that they are only proficient at one of the tasks. Here we report a high-performance bifunctional catalyst for both ORR and OER in both alkaline and neutral media, which is made of cobalt-embedded nitrogen doped carbon nanotubes. In OER, it shows an overpotential of 200 mV in 0.1 M KOH and 300 mV in neutral media, while the current density reaches 50 mA cm(-2) in alkaline media and 10 mA cm(-2) in neutral media at overpotential of 300 mV. In ORR, it is on par with Pt/C in both alkaline and neutral media in terms of overpotential, but its stability is superior. Further study demonstrated that the high performance can be attributed to the coordination of N to Co and the concomitant structural defects arising from the transformation of cobalt-phthalocyanine precursor.
authors: Department of Chemistry, Hong Kong University of Science and Technology , Clear Water Bay, Kowloon, Hong Kong, China.
authors: Zilong
authors: Z
authors: Wang
authors: Shuang
authors: S
authors: Xiao
authors: Zonglong
authors: Z
authors: Zhu
authors: Xia
authors: X
authors: Long
authors: Xiaoli
authors: X
authors: Zheng
authors: Xihong
authors: X
authors: Lu
authors: Shihe
authors: S
authors: Yang
keywords: bifunctional catalyst; carbon nanotube; cobalt-embedment; oxygen electrode reaction; wide pH range function