TiO2/pg-C3N4复合催化剂的制备及光催化性能

通过简单的超声剥离分散和水热法，成功制得了具有多孔结构的TiO₂/pg-C₃N₄复合催化剂.利用XRD、SEM、TEM、UV-Vis DRS和PL对样品的形貌、结构及光学性能进行了表征.在模拟太阳光照射下，以RhB和MO为模拟污染物考察了TiO₂/pg-C₃N₄的光催化性能.结果表明：当TiO₂占pg-C₃N₄的质量分数为5%时，制得的TiO₂/pg-C₃N₄（5：100）复合催化剂具有最优的光催化性能.TiO₂/pg-C₃N₄（5：100）对RhB的光催化降解途径为O^2·-和h⁺使整个共轭发色团结构发生裂解.TiO₂/pg-C₃N₄（5：100）光催化性能的提高一方面是由于多孔结构增加了光催化反应的活性位点；另一方面是由于TiO₂与pg-C₃N₄之间形成了Z型异质结，与传统的Ⅱ型异质结相比，该复合催化剂不仅使光生载流子分离效率提高，同时保留了pg-C₃N₄导带电子的强还原性和TiO₂价带空穴的强氧化性.

Preparation and photocatalytic properties of TiO2/pg-C3N4 composite photocatalyst

The porous TiO₂/pg-C₃N₄ composite photocatalyst was successfully prepared by combining ultrasonic with hydrothermal treatment. XRD, SEM, TEM, UV-Vis DRS and PL were applied to analyze its morphology, structure and optical properties. The photocatalytic activities of the as-prepared samples were evaluated by degradating the simulated pollutants (RhB, MO) in aqueous solution under simulated sunlighti llumination. The result showed that the TiO₂/pg-C₃N₄ (5:100) exhibited the best photocatalytic degradation performance among all photocatalists with different compositions. The photocatalytic degradation pathway of RhB was chromophore cleavage caused by O₂^- and h⁺. The improved photocatalytic performance of TiO₂/pg-C₃N₄ (5:100) was attributed to the fact that the active sites of the photocatalytic reaction were increased due to the porous structure, on the one hand, and a Z-scheme type heterojunction was formed between TiO₂ and pg-C₃N₄ on the other hand, which not only can increase the separation efficiency of electron-hole pairs, but also can retain the stronger reducibility of photo-generated electrons on the more negative CB of pg-C₃N₄ and higher oxidationability of photo-generated holes on the more positive VB of TiO₂, compared with the conventional type II heterojunction.