The Galvanic Protection of an Electrochemically Deposited Photocatalytic Au/FeAu Multilayered Nanowire—TiO2 Composite

Abstract

Gold nanoparticles on the surface of TiO2 is a useful water splitting photocatalyst but its performance can degrade in an oxygenated environment. To deter this degradation a novel composite photocatalyst consisting of electrodeposited Au/FeAu nanowires dispersed onto electrochemically deposited TiO2 on top of a stainless steel substrate was shown to inhibit degradation effects observed during water oxidation in base. A step in illumination and impedance modulated photocurrent spectroscopy (IMPS) provided a quantitative measure of the photoactivity and fate of minority carriers (holes, h+) in fresh and aged composites. The photogenerated current and h+ flux to the electrode surface of fresh catalyst significantly decayed within a period of 120 d in the Au/TiO2 system, whereas in the Fe-containing composite, these performance parameters were maintained for an extended period of time. Composite photocatalysts with Au/FeAu nanowires exhibiting modulations in porosity and composition of the alloy segment were also investigated. The catalyst photoactivity was adversely affected by either decreasing porosity and/or increasing Fe content within the alloy layer of nanowires combined with TiO2.