改性TiO_(2)的光生阴极保护研究进展

Research Advances on Modified Titanium Dioxide for Photogenerated Cathodic Protection

金属材料的广泛应用大大推动了社会的进步,但金属腐蚀现象的频繁发生也给人类生活及安全带来巨大损失与危害,并引发了一系列生态问题。常用的腐蚀防护方法包括合理选材、涂层技术、添加缓蚀剂以及运用电化学保护技术。其中,电化学保护技术之一的阴极保护广泛应用于金属腐蚀防护,但传统的阴极保护技术(如外加电流阴极保护)需要定期维护且监控、电源设备复杂,而牺牲阳极保护则需定期更换阳极金属且驱动电压低,具有一定的局限性。近20年来,光生阴极保护技术作为一种新兴的阴极保护技术,引起了研究者的广泛关注;其利用半导体作为光电中心、通过转换光辐射实现对被保护金属的光电化学保护,是一种真正高效、绿色环保的腐蚀防护技术。光生阴极保护的关键在于半导体材料的光电转换能力,以及其受光激发产生的光生电子向被保护金属表面转移并富集的能力。TiO_(2)是一种光电转换效率较高、无污染、稳定性好且耐光腐蚀的半导体材料,在光催化、光电转换以及光生阴极保护等领域具有广阔的应用前景。但TiO_(2)禁带宽度较宽、可见光响应能力低、光生载流子复合速率快、光电转换效率较低,这限制了其为金属材料持续提供阴极保护的能力。因此,对TiO_(2)进行改性研究,以突破TiO_(2)在光生阴极保护领域的应用瓶颈,成为了近期的研究热点。研究者们充分利用不同改性方法的优势,大幅提升了TiO_(2)的光电转换效率,并在如何实现暗态环境下持续有效的光生阴极保护这一瓶颈上有了很大的突破。本文从光生阴极保护原理出发,从金属沉积、离子掺杂、半导体复合(g-C_(3)N_(4)、Bi_(2)S_(3)、石墨烯等)、量子点敏化等改性手段着手,以TiO_(2)的光电性能及光生阴极保护效率提升为落脚点,重点评述并总结了不同改性TiO_(2)的光生阴极保护作用及发展,并回顾了笔者团队关于光电催化材料及腐蚀防护的研究进展与成果,对钢筋的光生阴极保护进行了可行性论证,最后对今后光生阴极保护的研究方向及研究重点提出了展望,为改性TiO_(2)半导体在光生阴极保护中的广泛应用提供有价值的参考。

The extensive application of metal materials has greatly promoted the social progress.However,the high-frequency metal corrosion causes huge losses and harm to human life and safety,which triggers a series of ecological problems as well.Generally,corrosion protection measures have been carried out,such as materials selection,coating,corrosion inhibitor and electrochemical protection.Cathodic protection,one of the electrochemical protection techniques,has been widely used in metal corrosion protection,yet there are some limitations for traditional cathodic protection technologies.As for traditional cathodic protection technologies,current-impressed cathodic protection requires regular maintenance,monitoring and complicated devices,while sacrificial anode cathodic protection with low output needs replacing anode metal regularly.In the past two decades,photogenerated cathodic protection,a novel approach of cathodic protection technology,has attracted a great deal of attention and confirmed to be truly efficient and eco-friendly,in which semiconductors serve as photoelectric center to transform solar radiation into electricity.The photoelectric conversion efficiency of semiconductor materials is focused on,as well as the ability of photogenerated electrons transferring and enriching onto the protected metal surface.TiO_(2) is a kind of photoelectric pollution-free semiconductor material,which shows good stability and excellent photocorrosion resistance.There are broad application prospects for TiO_(2) in the fields of photocatalytic activity,photoelectric conversion,photogenerated cathodic protection and others.However,the characteristics of wide band gap,poor photoresponse ability,high photocarrier recombination velocity and inefficient photoelectric conversion lead to insufficiency in offering sustained protection.Therefore,breaking through bottlenecks of TiO_(2) application in photogenerated cathodic protection by effective modification has recently received significant attention.Different modification methods for TiO_(2) to improve photoelectric conversion efficiency have been studied carefully.A great breakthrough in the substantiation of photogenerated cathodic protection in darkness has been performed.This review,proceeding from the mechanism of photogenerated cathodic protection,systematically introduces modification methods including metal deposition,ion doping,semiconductor compounding(g-C_(3)N_(4),Bi_(2)S_(3),graphene,etc.)and quantum dots sensitization.Advances of different modification methods of TiO_(2) in improving efficiency of photoelectric performance and photogenerated cathodic protection are emphatically discussed.The research advances and achievements of the author's team on photocatalytic materials and corrosion protection are reviewed.In addition,the feasibility of cathodic protection for reinforcement is demonstrated.Finally,future research direction and research emphases of photogenerated cathodic protection are proposed.This review provides new approaches for the wide application of modified TiO_(2)in photogenerated cathodic protection in a sustainable way.