A highly efficient α-Fe2O3/NiFe(OH)x photoelectrode for photocathodic protection of 304 stainless steel under visible light

Developing highly stable and broad spectrum responsive semiconductor photoelectrode materials without the use of hole scavengers is challenging for photoelectrochemical protection application. In this study, α-Fe2O3/NiFe(OH)x electrodes were successfully prepared by combining hydrothermal method and simple drop-casting technique. The morphology, structure, composition and optical property of the obtained electrodes were well characterized by SEM, XRD, XPS and UV–vis DRS. α-Fe2O3/NiFe(OH)x electrode exhibited enhanced photocathodic protection performance as compared to hematite (α-Fe2O3) electrode, and greatly shift photo potential and self-corrosion potential of the coupled 304 stainless steel into a more negative region. Remarkably, under visible light illumination, the prepared electrodes can protect the 304 stainless steel without the use of hole scavengers. Meanwhile, the photoanodes can maintain a better photo-stability without losing its activity. The possible mechanism for the enhanced photocathodic protection performance is proposed, which is involved with the fast hole transfer from hematite to NiFe(OH)x cocatalyst and generates high valence state Ni species to drive the water oxidation reaction. The reduced charge recombination will result in the effective electron transfer from the α-Fe2O3/NiFe(OH)x electrode to the 304 stainless steel and realize the effective protection. [Display omitted] •The hematite electrode could provide photocathodic protection for 304 stainless steel under visible light illumination.•The α-Fe2O3/NiFe(OH)x photoelectrode exhibited better photocathodic protection performance than α-Fe2O3 electrode.•The NiFe(OH)x cocatalyst can accelerate the water oxidation kinetics.•No hole scavengers are needed during the photocathodic protection process.