“Boosting the electron storage in a tiny volume occupied by carbon nanotubes should be attractive for miniaturizing storage batteries,” Kamat said. Such a high electron capacity turned the SWCNTs into supercapacitors, which can be useful in electronics applications. “At a concentration of 100 mg/L SWCNT, we observe complete disappearance of the 650 nm absorption band, thus indicating complete transfer of electrons to SWCNT.”Ĭomplete transfer consisted of 1 electron per 32 atoms of carbon atoms (building blocks of the SWCNTs), and occurred in just 10 nanoseconds. “The transfer of electrons represents charge equilibration between the two semiconductor systems having different Fermi levels,” the scientists explained. Because SWCNTs don’t have any detectable absorption in the visible range, this lack of color meant that some of the electrons trapped in the titanium dioxide were transferred to the SWCNTs. Electrons trapped in the titanium dioxide displayed a blue coloration (a 650-nm absorption band).īut when the researchers introduced SWCNTs to the titanium dioxide particles, the blue color decreased. When excited by a UV laser, titanium dioxide nanoparticles undergo charge separation, where some of the semiconductor’s electrons get trapped-an estimated 3,770 electrons per 12-nm-long nanoparticle. In addition, one can use the information to estimate the Fermi level of the semiconductor-carbon nanotube composite-an important parameter in evaluating the performance of SWCNT devices for electronic and photovoltaic applications.” “Our study provides a quantitative measure of the number of electrons stored in carbon nanotubes and its ability to discharge them on demand.
“Although the electron storage property of carbon nanotubes is well known, there is no convenient or simple way to make a quantitative estimate of storage capacity,” Kamat told. The study, published in ACS Nano, will be useful for the design of nanotubes as a way to direct the flow charge and boost photoelectrochemical performance for applications including electronic devices and solar cells. University of Notre Dame scientists Anusorn Kongkanand and Prashant Kamat monitored the transfer of electrons from semiconductor particles to SWCNTs as the composite system strained to achieve charge equilibrium.
0 kommentar(er)
