| Metal corrosion not only causes huge economic losses to human beings,but also may threaten people’s life safety,and the traditional metal corrosion protection methods have certain defects.TiO2 is a kind of N-type semiconductor material with high catalytic activity,strong oxidation ability,good chemical stability and low price,and it has been widely used as photocathode protection material for metal corrosion protection due to its excellent performance.In this paper,the microstructure and photocathodic protection performance of cadmium sulfide/graphene oxide/polyaniline modified epoxy coating@TiO 2 were studied with epoxy resin@TiO2 as the substrate,and the protection mechanism of the coating was analyzed theoretically.The main works carried out are as follows:（1）A cadmium sulfide/titanium dioxide（TiO2/CdS）-like spherical core-shell composite was synthesized in situ by a two-step hydrothermal method,and the photogenerated cathodic protection performance of TiO 2/CdS-modified epoxy coating on Q235 carbon steel（Q235 CS）was investigated.CdS was introduced into TiO2 as a sensitizer to form a heterojunction material and used as a filler to modify the epoxy resin,and then made to couple the coating of Q235 CS.Let the modified composite coating in the visible region of extended absorption and effective separation of photoelectron-hole pairs and synergistically improve the photoelectrochemical performance.The results showed that the photocurrent density of TiO2/CdS composite coating reached 0.0421 A/cm2 and corrosion potential reached-0.724 V,and the anticorrosion efficiency reached 79.47%.It indicates that the TiO2/CdS composite not only achieves the photogenerated cathodic protection of Q235 CS,but also achieves the physical shielding effect.（2）Based on（1）,a titanium dioxide/cadmium sulfide/graphene oxide/polyaniline（TiO2/CdS/GO/PANI）composite bifunctional coating was developed and prepared for photoelectric cathodic protection of Q235 CS to improve the coating photogenerated cathodic corrosion performance.The electrochemical performance parameters of photogenerated cathodic protection were investigated by coating the Q235 CS surface,and the results showed that the TiO2/CdS/GO composite coating could achieve a photocurrent density of0.053 A/cm2 and a corrosion potential of-0.74 V.The TiO2/CdS/GO/PANI composite coating exhibited remarkable photoelectrochemical performance with a photocurrent density of 0.15 A/cm2 and a corrosion potential of-0.8 V.The photocathodic protection mechanism is attributed to the potential energy difference between the Fermi energy and excitation energy levels,which leads to a higher electric field strength of the system at the semiconductor heterojunction interface,driving the direct flow of electrons to the Q235 CS surface.Meanwhile,the paper investigates the barrier effect and mechanism of the coating on the material protection under the combined effect of TiO 2/CdS/GO/PANI composite and epoxy resin.The corrosion protection efficiency of TiO2/CdS/GO composite coating reached 96.34%,and the corrosion protection efficiency of TiO2/CdS/GO/PANI composite coating was as high as 98.55%. |
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