Bi-layered CeO2/SrTiO3 nanocomposite photoelectrode for energy storage and photocathodic protection

•A bi-layer CeO2/SrTiO3 photoelectrode were fabricated for cathodic protection without external power.•The photoelectrode can be charged with illumination and continue to protect steel in the dark.•The photoelectrode is highly stable in alkaline electrolyte.

Photocathodic protection systems have been developed for corrosion control of metals using light energy, rather than supplied direct current or sacrificial anodes. However, one major challenge in photocathodic protection technique is that the anticorrosion performance of the photoelectrochemical response cannot be maintained in the absence of light illumination. This work, at its first time, reports the fabrication of a bi-layered CeO2/SrTiO3 nanocomposite photoelectrode to possess both the energy (photoelectron) storage and photocathodic protection abilities. Various analysis techniques including X-ray diffraction, scanning electron microscopy, energy dispersive spectrum and UV-visible spectroscopy were used to characterize the structure, morphology, composition and photo-response of the prepared photoelectrode. Cyclic voltammetry and electrochemical impedance spectroscopy were used to measure the electrochemical properties. Results demonstrate that the prepared CeO2/SrTiO3 nanocomposite photoelectrode can cathodically polarize the 304 stainless steel for photocathodic protection in 3.5 wt.% NaCl solution under illumination due to the generated photoelectrons by the outer SrTiO3 layer. The inner CeO2 layer can be charged at the photopotential. In the absence of illumination, the photoelectrode can maintain its anticorrosion performance by releasing the stored charges (photoelectrons) in the CeO2 layer to the steel for cathodic polarization.

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