TY - JOUR
T1 - From the inside-out
T2 - Leached metal impurities in multiwall carbon nanotubes for purification or electrocatalysis
AU - Suryanto, Bryan H.R.
AU - Fang, Tim
AU - Cheong, Soshan
AU - Tilley, Richard D.
AU - Zhao, Chuan
PY - 2018/1/1
Y1 - 2018/1/1
N2 - Multiwall carbon nanotubes (MWCNTs) have been applied extensively in various aspects of advanced materials development. However, the purification of multi-walled carbon nanotubes and the removal of internally confined metal impurities, without compromising the CNT structural integrity, have proved to be a great challenge. The presence of inherent metal impurities has increased the complexity and health risks associated with the use of MWCNTs. In this study, we developed a low-cost purification strategy to effectively remove encapsulated metal impurities. MWCNTs synthesized by Ni-catalyzed chemical vapor deposition (CVD), were annealed in the presence of melamine under Ar-atmosphere protection at 1000 °C. Electron microscopy indicated that the pyrolysis of MWCNTs in the presence of melamine induces the leaching of encapsulated Ni particles via the tube open-end or the defect sites found along the MWCNTs. With this method, the leached impurities were shown to be more susceptible and accessible to acid purification. Upon acid treatment, ultrapure MWCNTs with trace amounts of metallic impurities (<0.01 wt%) can be achieved. Alternatively, the leached metal nanoparticles could serve as highly efficient electrocatalytically active sites for oxygen evolution reactions with a turn over frequency (TOF) of 0.61 s-1.
AB - Multiwall carbon nanotubes (MWCNTs) have been applied extensively in various aspects of advanced materials development. However, the purification of multi-walled carbon nanotubes and the removal of internally confined metal impurities, without compromising the CNT structural integrity, have proved to be a great challenge. The presence of inherent metal impurities has increased the complexity and health risks associated with the use of MWCNTs. In this study, we developed a low-cost purification strategy to effectively remove encapsulated metal impurities. MWCNTs synthesized by Ni-catalyzed chemical vapor deposition (CVD), were annealed in the presence of melamine under Ar-atmosphere protection at 1000 °C. Electron microscopy indicated that the pyrolysis of MWCNTs in the presence of melamine induces the leaching of encapsulated Ni particles via the tube open-end or the defect sites found along the MWCNTs. With this method, the leached impurities were shown to be more susceptible and accessible to acid purification. Upon acid treatment, ultrapure MWCNTs with trace amounts of metallic impurities (<0.01 wt%) can be achieved. Alternatively, the leached metal nanoparticles could serve as highly efficient electrocatalytically active sites for oxygen evolution reactions with a turn over frequency (TOF) of 0.61 s-1.
UR - http://www.scopus.com/inward/record.url?scp=85043791349&partnerID=8YFLogxK
U2 - 10.1039/c7ta11257b
DO - 10.1039/c7ta11257b
M3 - Article
AN - SCOPUS:85043791349
SN - 2050-7488
VL - 6
SP - 4686
EP - 4694
JO - Journal of Materials Chemistry A
JF - Journal of Materials Chemistry A
IS - 11
ER -