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. Na 2 S, Na 2 SO 3 , Na 2 S 2 O 3 , Na 2 SO 4 , and NaCl was selected as sacrificial agents, in which the PCP performance is characterized by coupling TiO 2 and TiO 2 /ZnSe composites with 304 stainless steel. TiO 2 /ZnSe photoanode presented the best PCP performance in Na 2 S 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/cm 2 , 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.