Photothermal imaging of electrochemical reaction dynamics

Abstract

The thermal effects associated with a focused light source have been utilised in conjunction with a confocal scanning laser microscope to investigate localised reaction dynamics. This new technique termed scanning laser photothermal electrochemical microscopy (SLAPEM) was used to study hexacyanoferrate(II) oxidation at a gold electrode. The SLAPEM response is shown to be sensitive to electron transfer kinetics, enabling local variations in mass transport and kinetic control to be determined. Consequently, the important influence of the electrode edge and surface relief on electrochemical reactions at a disc electrode is shown. The origin of image features such as shadowing and hot spots are described and examined by investigating the influence of electrode potential, hexacyanoferrate(II) concentration and laser-spot velocity and size.