NiO/TiO2异质结构纳米管阵列膜对不锈钢的光生阴极保护及其储能性能

本工作通过修饰TiO₂制备半导体复合膜,提高其光吸收和光电化学性能,以期应用于光生阴极保护。先采用阳极氧化法在Ti表面制备TiO₂纳米管阵列膜,再应用水热处理法在膜表面沉积NiO纳米颗粒,形成具有异质结构纳米管复合膜。利用扫描电子显微镜、X-射线衍射、X-射线光电子能谱、紫外-可见吸收光谱、光致发光谱和光电化学技术对制备的纳米膜进行表征。结果表明,与纯TiO₂纳米管膜比较,NiO/TiO₂纳米管复合膜的光吸收扩展到可见光区。白光照射下,其在0.5 mol·L^?1 KOH和1 mol·L^?1 CH3OH混合液中的光电流密度达到176μA·cm^?2,是纯TiO₂纳米管膜的2倍。复合膜具有良好的光生阴极保护作用,与0.5 mol·L^?1 NaCl溶液中的403不锈钢耦连后,可使其电极电位下降440 mV,在光照2.5 h再转为暗态后,因具有电荷储存能力还可继续提供约15.5 h的阴极保护效应。

Photocathodic Protection on Stainless Steel by Heterostructured NiO/TiO2 Nanotube Array Film with Charge Storage Capability

Photocathodic protection by TiO₂ semiconductor materials for metals has interested many corrosion researchers for years.However,a pure TiO₂ semiconductor anode can only absorb ultraviolet light and cannot maintain the photocathodic protection in the dark.This has limited its practical applications to a great extent.Overcoming these limitations is significant as well as challenging.Therefore,the objective of this work is to prepare a modified TiO₂ composite film with visible light absorption and charge storage capabilities for application in photocathodic protection.First,we fabricated an ordered TiO₂ nanotube array film on a Ti substrate by electrochemical anodization.Then,we prepared NiO nanoparticles on the film via a hydrothermal reaction to obtain a p-n heterostructured NiO/TiO₂ nanotube array composite film.The properties of the prepared films were investigated by scanning electron microscopy,X-ray diffraction,X-ray photoelectron spectroscopy,UV-Vis absorption spectroscopy,photoluminescence spectroscopy,and photoelectrochemical techniques.The results indicated that the electrochemically anodized TiO₂ film had an anatase phase structure and consisted of vertically ordered nanotubes with an inner diameter of about 80 nm and length of 250 nm.After the NiO nanoparticles were deposited on the film,the TiO₂ nanotube array structure remained intact.The main phase of TiO₂ was still anatase,but the light absorption of the NiO/TiO₂ composite film was extended into the visible region,which was in contrast to that of the simple TiO₂ film.Moreover,the composite film showed lower photoluminescence intensities than the TiO₂ film,implying that a higher charge carrier separation efficiency could be achieved by modification with NiO.Under white light illumination,the photocurrent density of the NiO/TiO₂ composite film in a mixed solution of 0.5 mol·L^?1 KOH and 1 mol·L^?1 CH3OH reached 176μA·cm^?2,which was 2 times higher than that of the simple TiO₂ nanotube film,indicating that the composite film had improved photoelectric conversion efficiency and photoelectrochemical properties.The potential of 403 stainless steel(403SS)in 0.5 mol·L^?1 NaCl solution decreased by 380 and 440 mV relative to its corrosion potential when coupled to the TiO₂ film and NiO/TiO₂ composite film,respectively,under white light illumination.This indicated that the heterostructured NiO/TiO₂ film as a photoanode could produce more effective photocathodic protection on the steel as compared with the pure TiO₂ film.Even after 2.5 h of illumination,the composite film could continuously provide photocathodic protection to 403SS for about 15.5 h in the dark,suggesting that the NiO/TiO₂ composite film had a charge storage capability that was significant for its practical applications.