Surface-enhanced Raman spectroscopy (SERS) and silver nanoparticles are combining forces to boost sensitivity for detection of organic contaminants that occur at low-level concentrations in air and water. Researchers at the University of Notre Dame (Notre Dame, IN) have discovered that a semiconductor-graphene-metal film increases the local contaminant concentration adjacent to silver nanoparticles by absorbing organic molecules on its surface. And they are working toward the detection of environmental contaminants at increasingly lower levels.1
Under UV illumination, the electrons from semiconductor titanium dioxide (TiO2) are captured by the graphene oxide film and shuttled across the film to reduce metal ions into metal nanoparticles. This electron hopping allows the design of a side-separated semiconductor-metal nanoparticle architecture. While the conducting properties of graphene sheets deposited on various substrates are well understood, the researchers have demonstrated that the transport of electrons is not limited to the 2D plane. Here, the hopping of electrons from one side of the graphene allows for the side-selective deposition of silver nanoparticles.
1. I. V. Lightcap, S. Murphy, T. Schumer, and P. V. Kamat, J. Phys. Chem. Lett., 3, 11, 1453–1458 (2012).