The XPS system is a Physical Electronics (PHI 5800) ESCA System. This technique is widely used to determine quantitative atomic composition and qualitative analysis of different elements on the surfaces. It can provide information about surface layers or thin film structures.
This system is equipped with a sputtering ion gun, one dual-anode X-ray source, a monochromatic X-ray, and a dual beam charge neutralizer. This XPS system allows us to perform ISS (ion scattering spectroscopy), element depth profiling, and elemental mapping.
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.