Research Highlight

Light helps electrons hop

doi:10.1038/nindia.2011.57 Published online 26 April 2011

Researchers have designed a new nanohybrid that uses gold nanoparticles to connect a light-emitting molecule to single-walled carbon nanotube. Electrons travel smoothly through the link, making it suitable for devising both chemical and biological sensors.

Carbon nanotubes are well-known to have excellent electron-accepting and transporting properties. Attaching metal nanoparticles to the surface of a nanotube makes it a potential candidate for a transistor. However, nanotube–nanoparticle systems are not well-explored for the harnessing of light energy. To achieve this, the researchers prepared single-walled carbon nanotubes attached with ruthenium trisbipyridine chromophores (light-emitting molecules) in either the presence or absence of gold nanoparticles.

They also linked ruthenium directly to the gold nanoparticles. The nanohybrid systems were exposed to visible, ultraviolet and near-infrared light to study the efficacy of their light-induced electron transfer. The researchers observed that an efficient light-induced electron transfer process occurred from ruthenium to the nanoparticle-covered nanotube. However, no electron transfer occurred when ruthenium was directly linked to the gold nanoparticles or to the nanotubes.

The electrons moved from ruthenium to the nanotube and then back to ruthenium. The study found that electron transfer was driven through the gold–nanotube heterojunction.

"Forward electron transfer is two orders of magnitude faster than backward electron transfer, making these nanohybrid systems promising for optoelectronic and artificial photosynthetic device applications," says lead researcher K. George Thomas. "Similar phenomenon could be observed using palladium and platinum metal nanoparticles, which will increase the forward electron transfer rates, making nanotubes much better electron acceptors."

The authors of this work are from: Photosciences and Photonics Group, National Institute for Interdisciplinary Science and Technology (NIIST), CSIR, and India School of Chemistry, Indian Institute of Science Education and Research, Thiruvananthapuram (IISER-TVM), Thiruvananthapuram, India.


  1. Pramod, P. et al. Gold nanoparticle-functionalized carbon nanotubes for light-induced electron transfer process. J. Phys. Chem. Lett. 2, 775-781 (2011) | Article |