Preparation of NiO/TiO2 p-n heterojunction composites and its photocathodic protection properties for 304 stainless steel under simulated solar light

The NiO/TiO2 p-n heterojunction composites were synthesized by electroless plating and annealing, which resulted in TiO2 nanotube arrays coated with a layer of NiO particles. The morphology, composition, and structure of NiO/TiO2 p-n heterojunction composites were corroborated by scanning electron microscopy, X-ray diffraction, FT-IR spectra, X-ray photoelectron spectroscopy, and UVevis diffuse reflectance spectroscopy. The influences of electroless plating time and annealing temperature on the photoelectrochemical performance of the composites were investigated, and their photocathodic protection performance for 304SS under visible light irradiation were also evaluated in 3.5% NaCl solution through open-circuit potential, photoresponse spectra, and Tafel polarization curves. NiO/TiO2 heterojunction composites prepared under optimum conditions induce considerable enhancement of light absorption and exhibit excellent photoelectrochemical performance, which provide better photocathodic protection for 304SS. (C) 2017 Elsevier B.V. All rights reserved.