Development of visible light sensitive metal oxide photocatalysts having a functional accumulation properties by controlling surface structure

提出了一种只在S或氮掺杂的二氧化钛表面掺杂Fe~(2+)~(3+)&Gt~(2+)的新方法。在较宽的入射光波长(包括紫外光和可见光)下，吸附在S或氮掺杂的TiO2光催化剂上的Fe~(2+)&lt；3+&gt；离子对异丙醇的氧化活性比未经Fe~(2+)&lt；3+&gt；离子处理的S或氮掺杂的TiO2光催化剂显著提高。当S掺杂的二氧化钛颗粒对Fe~(2+)~(3+)和Gt~(3+)的吸附量为0.90wt%时，光催化活性达到最大。在含Fe~(2+)~(3+)和Gt~(3+)离子的N掺杂二氧化钛中，Fe~(2+)~(3+)和~(3+)离子的最佳掺杂量为0.36wt%。当Fe~(2+)和L~(3+)&Gt~(3+)离子的量大于1.0wt%时，吸附在S或N掺杂的TiO2光催化剂上的Fe~(2+)和L~(3+)&Gt~(2+)离子的光催化活性逐渐降低。此外，当S掺杂或氮掺杂的TiO2光催化剂经NaBH4还原后空气氧化后，吸附了Fe~(2+)、Lt；3+、Gt~(2+)离子，其光催化活性进一步提高。…在这种情况下，Fe~(2+)~(3+)~(3+)和N~(3+)在S掺杂的TiO2光催化剂表面的最佳吸附量分别为2.81wt%和0.88wt%。在处理过程中，吸附在S掺杂或氮掺杂的二氧化钛上的Fe~(2+)~(3+)&Gt~(2+)离子被还原生成金属铁，在曝气条件下，Fe被再次氧化生成Fe~(2+)&lt；3+~(2+)离子。经处理后，S掺杂的TiO2光催化剂上吸附的Fe~(2+)、Lt；3+、Gt~(2+)离子的晶体结构和异丙醇的吸附性能发生了变化。丙醛、己醛、正庚醛、五氟苯甲醛和苯甲醛在表面修饰的SiO_2-TiO_2催化剂上的氧化效率远高于未经表面修饰的SiO_2-TiO_2光催化剂。对于碳链修饰的SiO_2-TiO_2光催化剂而言，提高其光催化活性的一个重要因素是载体与SiO_2-TiO_2表面引入的烷基硅基之间的疏水相互作用。苯基改性的SiO_2-TiO_2对苯甲醛的光催化氧化活性高于SiO_2-TiO_2-C_6。并且，五氟苯甲醛在SiO_2-TiO_2-C_8(F)链上的氧化比在SiO_2-TiO_2-C_8上进行得更好。这些结果表明，SiO_2-TiO_2表面引入的官能团对有机化合物的光催化氧化具有重要的选择性。较少

A new method to dope Fe^<3+> ions only onto the surface of S-or N-doped TiO_2 is proposed. The photocatalytic activities of Fe^<3+> ions adsorbed on S-or N-doped TiO_2 photocatalysts for oxidation of 2-propanol are markedly improved compared to those of S-or N-doped TiO_2 without treatment of Fe^<3+> ions under a wide range of incident light wavelengths, including UV light and visible light. When the amount of Fe^<3+> ions adsorbed on S-doped TiO_2 particles was 0.90 wt%, photocatalytic activity reached maximum. In the case of N-doped TiO_2 with Fe^<3+> ions, the optimum amount of Fe^<3+> ions was 0.36 wt%. The photocatalytic activities of Fe^<3+> ions adsorbed on S-or N-doped TiO_2 photocatalysts decreased gradually when the amount of Fe^<3+> ions was greater than 1.0 wt%. In addition, when S-or N-doped TiO_2 photocatalysts adsorbed with Fe^<3+> ions was observed after reduction by NaBH_4 followed by air oxidation, further improvement in their photocatalytic activities were observed. … More In this case, the optimum amounts of Fe^<3+> adsorbed on the surfaces of S-and N-doped TiO_2 photocatalysts were 2.81 and 0.88 wt%, respectively. During the treatment, Fe^<3+> ions adsorbed on S-or N-doped TiO_2 were reduced to generate metal Fe, and Fe was reoxidized again to form Fe^<3+> ions under an aerated condition. After the treatment, the crystal structure of Fe^<3+> ions adsorbed on S-doped TiO_2 and adsorbtivity of 2-propanol on the photocatalyst were changed.Surfaces of SiO_2-covered TiO_2 photocatalysts (SiO_2-TiO_2) were modified with alkylsilyl groups such as hydrocarbon, fluorocarbon, and phenyl groups. Oxidation of propanal, hexanal, nonanal, pentafuluorobenzaldehyde, and benzaldehyde proceeded much more efficiently on the surface-modified SiO_2-TiO_2 particles than on SiO_2-TiO_2 photocatalysts without surface modification. In the case of SiO_2-TiO_2 photocatalysts modified with hydrocarbon chains, one of most important factors for improvement of the photocatalytic activities of surface-modified TiO_2 photocatalysts is the hydrophobic interaction between substrates and alkylsilyl groups introduced onto SiO_2-TiO_2 photocatalysts. SiO_2-TiO_2 modified with phenyl groups is more active in the photocatalytic oxidation of benzaldehyde than SiO_2-TiO_2-C_6. Furthermore, oxidation of pentafluorobenzaldehyde proceeded more favorably on SiO_2-TiO_2-C_8(F) chains than on SiO_2-TiO_2-C_8. These results indicated that the functional groups introduced onto the surface of SiO_2-TiO_2 play an important role in showing selectivity for photocatalytic oxidation of organic compounds. Less