【作者】 廖高祖；

【导师】 全燮；

【作者基本信息】 大连理工大学 ， 环境工程， 2011， 博士

【摘要】 光催化技术是一种新型有效的环境污染控制技术,具有环境友好,污染物分解彻底等优点。同时,由于具有可利用太阳能的可能性而受到广泛的关注。但目前以TiO2为代表的光催化剂存在可见光利用效率低和量子效率低等缺点,这些因素限制了光催化技术的进一步发展。导电聚合物是一种具有半导体特性的高分子聚合物,具有较强的可见光吸收性能和电荷迁移能力。将导电聚合物与其他半导体进行复合形成异质结可以促进光生电荷的有效分离；同时通过引入光子晶体和核壳介孔微球等结构的反射效应、散射效应和慢光效应可以实现对可见光的有效富集,以上两方面协同作用可以实现可见光下对污染物的高效光催化降解。本论文围绕以上内容,主要开展了以下几个方面的工作：(1)结合模板法、液相沉积法、旋转涂覆法和浸渍法制备了反蛋白石TiO2光子晶体耦合的TiO2/聚3-己基噻吩(P3HT)复合光催化剂(Bilayer TiO2/P3HT)。Bilayer TiO2/P3HT由内层的反蛋白石TiO2和外层的纳米颗粒TiO2组成,其中反蛋白石TiO2具有规则的面心立方体结构,TiO2纳米颗粒层是由5-25 nm的纳米颗粒组成。经过P3HT修饰之后,Bilayer TiO2/P3HT仍然呈现出锐钛矿TiO2的晶型结构,由于光子晶体Ti02的禁带反射效应和禁带红边缘的慢光效应,Bilayer TiO2/P3HT对可见光的吸收要明显强于传统的NP-TiO2/P3HT。可见光下对亚甲基蓝(MB)的光催化降解实验结果表明,在6h内Bilayer TiO2/P3HT对MB的光催化降解反应动力学常数是传统的NP-TiO2/P3HT的2.08倍。这些结果说明光子晶体与P3HT/TiO2异质结的协同作用可以有效的提高可见光下的光催化能力。(2)结合水热法和化学吸附法制备了聚苯胺(PANI)修饰的核壳结构的介孔TiO2微球光催化剂(PANI/M-TiO2)。PANI/M-TiO2具有独特的介孔核壳结构,其比表面积达到125 m2/g。PANI的修饰没有改变M-TiO2的锐钛矿的晶型结构。由于多重散射、反射效应以及较大的比表面积,PANI/M-TiO2对可见光的吸收要明显强于传统的PANI/NP-TiO2。其中PANI与M-TiO2的初始质量比为6%的复合光催化剂显示了最好的光催化活性,可见光下对于罗丹明B (RhB)和4-氯酚(4-CP)的降解动力学常数分别是传统的PANI/NP-TiO2的5.04倍和2.03倍。(3)结合直接热聚合法和超声吸附法制备了石墨相氮化碳(g-C3N4)和石墨烯氧化物(GO)复合的可见光催化剂。其中g-C3N4是由单层石墨状的七嗪环片层沿着c轴方向的堆垛而形成。GO表现出薄纱状褶皱和卷曲的织构,表面含有丰富的羟基、羧基、环氧基等含氧基团。g-C3N4与GO通过超声吸附复合之后,所得到的g-C3N4/GO复合光催化剂对可见光的吸收有所增强,而且g-C3N4与GO之间光生电荷能够有效的迁移和分离。可见光下对RhB的光催化降解实验结果表明g-C3N4/GO复合光催化剂具有较好的光催化活性,其降解动力学常数是g-C3N4的3.80倍。以上结果表明,合理的设计导电聚合物异质结光催化剂的形貌和结构,能够实现对可见光的有效富集,从而增加对可见光的吸收效率；导电聚合物和其他半导体之间形成的异质结能够促使光生载流子的有效迁移和分离,两方面协同作用,实现了可见光下对污染物的高效光催化降解。本论文为高效可见光光催化剂的设计和制备提供了可行的方法,为光催化技术的进一步应用与发展提供了有价值的参考。更多还原

【Abstract】 Photocatalysis is one of the attractive efficient environmental pollution control technique due to its environmental friendly property, excellent photocatalytic activity and potential in solar useless. However, there are two problems for the mostly studied photocatalyst TiO2, which were the vital factors to the further development of photocatalysis. One is the limitation of utilization of visible light; another one is low quantum efficiency. Conducting polymers (CPs) was a unique organic semiconductor, which possesses efficient visible light absorption and charge transfer ability. The separation of photogenerated charge could be facilitated when CPs combined with other semiconductors owing to the heterojunction built between them; on the other hand, the visible light harvest efficiency of photocatalyst could be enhanced by employing the multiple scattering effect, reflection effect and slow photons effect of photonic crystals and mesoporous core-shell microspheres structure. The synergy of the two factors as stated above would enhance the efficiency of photocatalysis under visible light irradiation. In this dissertation, the following work has been done:(1) Photonic crystal coupled TiO2/P3HT hybrid photocatalyst on FTO substrate (Bilayer TiO2/P3HT) were fabricated by the combination of template method, liquid phase deposition method, spin coating and dipping method. The Bilayer TiO2/P3HT was composed of inverse opal TiO2 layer and TiO2 nanoparticle layer. The inverse opal TiO2 was regular with FCC. The TiO2 nanoparticle layer was composed of TiO2 nanoparticle with diameter in the range 5-25 nm. After modification with P3HT, the Bilayer TiO2/P3HT composite photocatalyst was still in anatase. Moreover, the visible light absorption of Bilayer TiO2/P3HT was more intensive than the conventional NP-TiO2/P3HT in the range of 400-650 nm because of the reflection effect and slow photos effect of inverse opal TiO2. The result of photocatalytic degradation of MB under visible light irradiation illustrated that the pseudofirst-order kinetic constant using the Bilayer TiO2/P3HT was 2.08 times as great as that using NP-TiO2/P3HT. The photocatalytic mechanism of photodegradation of MB was discussed.(2) PANI modified core-shell mesoporous TiO2 microspheres (PANI/M-TiO2) were fabricated by the combination of hydrothermal method and chemisoroption method. The morphology of PANI/M-TiO2 was microspheres with unique core-shell structure..The specific surface area of PANI/M-TiO2 was 125 m2/g. The PANI/M-TiO2 composite photocatalyst with the mass proportion of 6% showed the best photocatalytic peformance. The visible light absorption of 6% PANI/M-TiO2 was more intensive that of conventional PANI/NP-TiO2 because of the multireflection effect and large surface area of PANI/M-TiO2. The result of photocatalytic degradation of RhB and 4-CP under visible light irradiation illustrated that the pseudofirst-order kinetic constant using the 6% PANI/M-TiO2 was 5.04 times and 2.03 times as great as that using conventional PANI/NP-TiO2, respectively. The photocatalytic mechanism of photodegradation of RhB and 4-CP was discussed.(3) The graphene oxide and graphitic carbon nitride (g-C3N4/GO) was prepared by directly heating melamine and ultrasonic adsorption method. The g-C3N4 was composed of graphite-like stacking of the tri-s-triazine units. The GO displayed flake-like shapes of with wrinkles and ripples. The surface of GO contained much functional groups, such as-COOH,-OH,-C-O-C-. After ultrasonic adsorption, g-C3N4 combined with GO via strong bonds. The absorption of g-C3N4/GO was more intensive than that of g-CsN4. Moreover, efficient photocharge separation process occured in the g-CsN4/GO composite photocatalyst. The result of photocatalytic degradation of RhB under visible light irradiation illustrated that the pseudofirst-order kinetic constant using the g-C3N4/GO was 3.80 times as great as that using conventional g-C3N4.The results of the experiments in this dissertation demonstrated that the visible light absorption of photocatalyst could be harvested efficiently via the construction of photocatalyst with suitable morphology and structure; the heterojunction built between CPs and other semiconductors benefited the separation of photogenerated charge. The synergy effect of the two aspects could enhance the efficiency of photocatalysis under visible light irradiation, which supplied feasible approaches for the design and fabrication of efficient visible light photocatalyst, and promoted the application and development of photocatalytical technology further.更多还原