Z机制光催化三元复合材料RGO/WO_3/g-C_3N_4结构及光催化性能

以一步水热法合成了还原氧化石墨烯/三氧化钨/石墨相氮化碳(RGO/WO_3/g-C_3N_4)三元光催化复合材料,并对其结构、形貌及光电性能进行了表征。以罗丹明B(RhB)和盐酸四环素(TC-HCl)为降解目标物,评价了三元复合材料的光催化性能。基于自由基捕获实验和光催化反应结果分析了三元复合材料的光催化机制。结果表明:三元光催化复合材料中,三种物质紧密接触形成异质结构,与WO3和g-C_3N_4单体及其二元复合材料相比,其可见吸收光谱有明显的红移,具有更低的光致发光光谱强度。复合材料有效的改善了电子-空穴对的复合,具有很好的光催化活性,最优配比组成的样品为0. 2%RGO/WO_3/g-C_3N_4,光照240 min后,对Rh B降解效果高达97. 58%,其光催化效果优于WO_3、g-C_3N_4、RGO/g-C_3N_4和WO_3/g-C_3N_4。催化降解过程中的主要活性物种是·O_2^-,其次是h^+、·OH,反应过程中半导体的电子转移机制符合Z机制。

Structure and Photocatalytic Activities of RGO/WO3/g-C3 N4 Ternary Photocatalytic Composite with Z-scheme

A reduced graphene oxide/tungsten trioxide/graphitic carbon nitride(RGO/WO 3/g-C 3N 4) ternary photocatalytic composite was prepared through one-step hydrothermal method. The structure, morphology and optical properties of the as-prepared samples were characterized. The photodecomposition performance was evaluated through photocatalytic degradation of Rhodamine B(RhB) and Tetracycline Hydrochloride(TC-HCl) under Xenon light illumination. The experiments of active species trapping and photocatalytic reactions were performed to investigate its photocatalytic mechanism. The results show heterojunction structure was built by close contaction of three precursors in ternary. Compared with WO 3, g-C 3N 4 and their binary composites, slight red shift of visible absorption spectrum and low photoluminescence intensity were observed which indicated that the composite had noteworthy improvement in separation of electron-hole pairs. The ternary composite has excellent photocatalytic activity. The removal rate of RhB was up to 97.58% when 0.2%RGO/g-C 3N 4/WO 3 with the optimized content was used and 240 min illumination, which was better than that of WO 3, g-C 3N 4, RGO/g-C 3N 4 and WO 3/g-C 3N 4. The main active species in the process was ·O - 2, h + and ·OH. It is speculated that the electron transfer between semiconductors acted up to the Z-mechanism.