Surface-plasmon-resonance imaging could enable mass screening of catalyst nanoparticles

Tempe, AZ--Nongjian Tao, a researcher at Arizona State University’s Biodesign Institute, has developed a way to use plasmonics to measure catalytic reactions of single nanoparticles and multiple particles printed in arrays. Nanoparticle catalysts are used for production of polymers and biofuels, improving pollution and emission control devices, enhancing reactions essential for fuel-cell technology and the synthesis of new drugs, and in myriad other applications.

Conventional measurement methods measure the average properties of many nanoparticles, which smears out the varying properties of individual nanoparticles. The new method relies instead on imaging electrochemical reactions optically based on surface-plasmon resonance. Every electrochemical reaction is accompanied by the exchange of electrons between reactants and electrodes, and the conventional electrochemical methods, including SECM, detect the electrons.

“Our approach is to measure electrochemical reactions without directly detecting the electrons,” says Tao. “The trick is to detect the conversion of the reactant into reaction products associated with the exchange of electrons.” Such conversion in the vicinity of the electrode affects plasmons, causing changes in light reflectivity, which the technique converts to an optical image.

In the current study, platinum nanoparticles acting as electrochemical catalysts are investigated by means of the new technique, known as plasmonic electrochemical imaging. The method combines the spatial resolution of optical detection with the high sensitivity and selectivity of electrochemical recognition. Tao’s group examined the electrocatalytic activity of platinum nanoparticles printed in a microarray on a gold thin-film electrode, demonstrating for the first time the feasibility of high-throughput screening of the catalytic activities of nanoparticles.

Results of the study appear in this week’s advanced online edition of the journal Nature Nanotechnology.

Source: http://www.biodesign.asu.edu/news/new-imaging-technique-homes-in-on-electrocatalysis-of-nanoparticles-