Successive ionic layer adsorption and reaction (SILAR) deposition of nickel sulfide on the Fe 2 O 3 nanotube for efficie
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ORIGINAL PAPER
Successive ionic layer adsorption and reaction (SILAR) deposition of nickel sulfide on the Fe2O3 nanotube for efficient photocathodic protection of stainless steel under visible light Mohamad Mohsen Momeni1 · Yousef Ghayeb1 · Mehrdad Akbarnia1 · Zahra Barati1 Received: 7 March 2020 / Accepted: 29 June 2020 © Iranian Chemical Society 2020
Abstract Nickel sulfide deposited on the Fe2O3 nanotube surfaces (NiS/Fe2O3) via successive ionic layer adsorption and reaction (SILAR) method was applied as a novel photoanode in the photocathodic protection in order to retard the corrosion of 403 stainless steel. The morphology, crystal structure, and elemental composition were characterized by scanning electron microscopy, X-ray diffraction, and energy dispersive X-ray. Furthermore, measurements of the open-circuit potential, photocurrent density with time (j − t), and potentiodynamic polarization curves (Tafel plot) were used to assess the photocathodic protection effects of the films prepared. The morphology, visible light response, and the corresponding photoelectrochemical performances of NiS/Fe2O3 were affected by the number of SILAR cycles. Considerable photoelectrochemical properties such as enhanced photocurrent density and negative shift corrosion potential were shown by NiS/Fe2O3 in comparison with bare Fe2O3 nanotubes. Optimal photoelectrochemical characteristics were shown by NiS/Fe2O3 prepared with 5 SILAR cycles (sample C5), based on the results obtained. Improved photocathodic protection effect was shown by the novel NiS/ Fe2O3 films as photoanodes, causing the potential of the coupled stainless steel in 3.5% NaCl solution to decrease by 200 mV relative to its corrosion potential. Keywords Photocathodic protection · Corrosion · 403 Stainless steel · SILAR deposition · Nickel sulfide · Fe2O3 nanotube · Photoelectrochemical
Introduction Given its outstanding anti-corrosion character, stainless steel has been extensively applied as the engineering material. However, the pitting corrosion of stainless steel is a serious drawback, which limits its application in solutions containing chloride ion [1–3]. Some of the important approaches to overcome this shortcoming include the application of anticorrosion coating, corrosion inhibitors, and electrochemical protection [1–8]. Regretfully, these methods usually result in the loss of materials and energy. A novel method for the protection of metals from corrosion in the absence of additional current or sacrificial anodes is photocathodic protection (PCP). In this method, which does not involve high energy * Mohamad Mohsen Momeni [email protected] 1
Department of Chemistry, Isfahan University of Technology, Isfahan 84156‑83111, Iran
consumption and maintenance expenses, the electrons generated in photoanode under illumination are transferred to the metal coupled with the photoanode. Consequently, the open-circuit potential of the metal shifts to a more negative value compared with its corrosion potential, controlling the metal corrosion [2, 9–
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