(722b) Intensity Modulated Photocurrent Spectroscopy (IMPS) Used to Detect Photoactive Intermediates during Niw Electrodeposition

Intensity modulated photocurrent spectroscopy (IMPS) is a technique conventionally used to characterize the semiconductor/electrolyte interface.  It is used here in a new way, to verify the presence of adsorbed, photoactive intermediates during the electrodeposition process, using NiW alloy electrodeposition as an example. Interest in NiW alloys are related to their high corrosion resistance, ability to catalyze the hydrogen evolution reaction from water, and superior wear resistance. The NiW deposition behavior from aqueous solutions is described as a couple reaction mechanism and better understanding of the mechanism can help to control the deposit composition which in turn is related to the resulting properties. To this end, IMPS was used to examine codeposition using an ammonia free citrate-boric acid electrolyte. The IMPS spectra was generated for different applied potentials. A significant current response to the incident modulated UV light was detected where steady state NiW codeposition takes place. The results confirm the presence of photoactive intermediates during codeposition, and is the first use of this technique in the electrodeposition process resulting in a metallic product.