Enhancing photoelectrochemical cathodic protection performance by facile tuning sulfur redox state in sacrificial agents

Photocathodic protection (PCP) performance is restricted by the photogenerated charges separation efficiency. This study reported a facile approach to enhance PCP performance. Na2S, Na2SO3, Na2S2O3, Na2SO4, and NaCl was selected as sacrificial agents, in which the PCP performance is characterized by coupling TiO2 and TiO2/ZnSe composites with 304 stainless steel. TiO2/ZnSe photoanode presented the best PCP performance in Na2S media. The maximum potential drop is 466.7 mV, which is about 3.5 times higher than that of in NaCl media. The corresponding photocurrent density is 270.7 μA/cm2, which is about 10 times higher than that of in NaCl media. Based on circle voltammetry and ultraviolet photo-electron spectroscopy characterization, it was found that the redox potential of the sacrificial reagent governs the migration and consumption of photogenerated holes of the photoanode.