Investigation Of Photogenerated Cathodic Protection Performance Of MXene/TiO₂ Composites For 304 Stainless Steel

In recent years,titanium dioxide photocathodic protective coatings have been widely used in the anticorrosion of metals.However,there are still some shortcomings in the application of TiO₂ photogenerated cathodic protective coatings:serious carrier recombination;low utilization of sunlight;inability to provide protection for metals in the dark state,etc.Therefore,in this paper,in order to improve the photogenerated cathodic protection performance of TiO₂,TiO₂ was grown in situ on the MXene sheet by calcining Ti₃C₂ MXene,and TiO₂/Ti₃C₂ was compounded with TiN and PANI successively.The structural characteristics of the composite were characterized by XRD,UV-Vis absorption spectroscopy,and XPS.The microstructures were observed by SEM and TEM.The photogenerated cathodic protection performance of ternary and quaternary composites on 304 stainless steel was investigated by photoelectrochemistry,polarization curve and AC impedance spectroscopy.In addition,the photogenerated cathodic protection effects of ternary and quaternary composites combined with epoxy resin coating were also studied in this paper.Firstly,TiO₂ nanoparticles were grown on MXene sheets by calcination method to explore the effect of calcination temperature on the structure and properties of MXene.The calcined MXene was composited with TiN to explore the effect of TiN content on the structure and properties of the calcined MXene.The results showed that when the calcination temperature was 450℃,the degradation rate of calcined MXene to methylene blue under ultraviolet light was 92%,and the degradation rate was higher than that of TiO₂/Ti₃C₂ composites obtained by calcination temperature of 350℃and550℃.When TiN was recombined with TiO₂/Ti₃C₂,the charge separation efficiency of TiO₂ was improved and the recombination of electron-hole pairs was suppressed due to the localized surface plasmon resonance effect of TiN and the generation of hot electrons.When the TiN content was 4%,the forbidden band width of TiO₂/Ti₃C₂/TiN composite was 2.65e V,which was lower than that of other TiN composites,and the photogenerated cathodic protection effect on 304 stainless steel was the best.Secondly,the calcined MXene was compounded with aniline by chemical oxidation method,and the effect of the mass ratio of calcined MXene and aniline on the structure and properties of calcined MXene was investigated.The results showed that when PANI was recombined with TiO₂/Ti₃C₂,the charge separation efficiency of TiO₂was improved due to PANI’s ability to absorb visible light and transport holes.When the mass ratio of calcined composite and aniline was 2:1,the photoelectric protection performance of TiO₂/Ti₃C₂/PANI composite on 304 stainless steel was the best.The TiO₂/Ti₃C₂/TiN/PANI quaternary composite was prepared with the optimum content of titanium nitride and the optimum mass ratio of calcined MXene and aniline.The photogenerated cathodic protection effects of the quaternary composite with TiO₂/Ti₃C₂/TiN and TiO₂/Ti₃C₂/PANI were compared,and the long-term protection of the epoxy resin composite coating of the quaternary composite was investigated.The results showed that the photogenerated cathodic protection effect of the quaternary composite was better than that of the TiO₂/Ti₃C₂/TiN and TiO₂/Ti₃C₂/PANI composites.The long-term protection of 304 stainless steel by the quaternary composite epoxy composite coating after illumination is obviously better than that of the composite coating without illumination.