Dr. Yongqiang Tan got his B.S. degree from China University of Petroleum (Beijing) in 1996. In the same year, he joined China Petroleum and Chemical Co. (Sinopec) where he worked as an engineer and participated in the research of a new catalyst for the preparation of acrylonitrile from propylene by ammoxidation. He received his PhD degree in Chemical Engineering from the University of Mississippi in 2004. His research was focused on surfactants and interfacial phenomena. He joined Dr. Resasco's group as a postdoctoral research associate after graduation. His current work is focused on the dispersion and characterization of SWNTs.
The role of water in carbon feed on the surface-guided growth of horizontally aligned single-walled carbon
nanotubes (HA-SWCNTs) was investigated. It is shown that the amount of water can be optimized to favor HA-SWCNT growth, which is proposed to be due to selective etching of carbon deposits at carbon–metal interface. Without water, nanotube–nanotube interaction and carbon accumulation at the interface are disproportionately large compared to the rate of nanotube growth, leading to catalyst deactivation. With excess water, suppression of nanotube growth occurs, resulting in reduced carbon yield on the surface.
Intermediate carbon/water feed ratios achieve cleaner growth with high efficiency.