PEDOT:PSS helps to reveal the decisive role of photocurrent and photopotential on the photoinduced cathodic protection performance

Abstract

Photoinduced cathodic protection (PICP) performance of a semiconductor is closely related to its photoelectric conversion performance. However, this relationship is not clear up to date. In this work, PEDOT:PSS was added during the preparation process of ZnO electrode, endowing the obtained ZnO/PEDOT:PSS electrode with enhanced charge transfer and positive shifted Fermi level. Compared with ZnO, the ZnO/PEDOT:PSS shows larger photocurrent and more positive photopotential, which have opposite effects on the final PICP performance. Thus, the effect of photocurrent and photopotential on the PICP performance can be separately investigated in this paper. ZnO/PEDOT:PSS shows increased PICP performance for Cu but reduced PICP performance for 316L SS. These disparate PICP results were further revealed by the comparison of the photoinduced Tafel plots of semiconductors and the Tafel plots of the protected metals for the first time. And the synergistic mechanism of the photoelectric conversion property of semiconductors and the corrosion rates of the metals are finally clarified. Furthermore, a series ZnO photoelectrodes with different photocurrents and constant photopotential were obtained by simply controlling the electrode area. The comparison of their PICP performance reveals the efficient way to improve the PICP performance from the perspective of both photocurrent and photopotential. Therefore, this work not only reveals the synergistic mechanism of semiconductors and metals on the PICP performance, but also plays an important role in guiding how to efficiently improve the PICP performance.