Green Design

Detecting Contaminants in Water

Many organic contaminants in the air and in drinking water need to be detected at very low-level concentrations. Research published by the laboratory of Prashant V. Kamat, the John A. Zahm Professor of Science at the University of Notre Dame, could be beneficial in detecting those contaminants.

The Kamat laboratory uses Surface-Enhanced Raman Spectroscopy to make use of silver nanoparticles to increase the sensitivity limit of chemical detection. Researchers in this study have prepared a semiconductor-graphene-metal film that has distinct advantages - the absorption of organic molecules on the film’s graphene surface increases the local contaminant concentration adjacent to silver nanoparticles.

The researchers have investigated the use of graphene oxide films in which the semiconductor titanium dioxide (TiO2) and metal nanoparticles are deposited on opposite sides of the graphene surface. “We are currently working toward the detection of environmental contaminants at even lower levels,” Kamat says. “Careful control of metal size and loading will be the key to optimize strips for testing water quality.”

Under UV illumination, the electrons from TiO2 are captured by the graphene oxide film and shuttled across the film to reduce metal ions into metal nanoparticles. This electron-hopping process across the graphene oxide film allows the design of a side-separated semiconductor-metal nanoparticle architecture.

(University of Notre Dame)