BiVO_4/Bi_6O_6(OH)_3(NO_3)_3复合光催化剂的制备及光催化性能研究

以Bi(NO_3)_3·5H_2O和NH_4VO_3为原料,控制水溶液介质p H及反应时间,采用水热合成法制备钒酸铋(BiVO_4)及其复合物(BiVO_4/Bi_6O_6(OH)_3(NO_3)_3).利用X-射线粉末衍射、扫描电子显微镜和紫外-可见漫反射吸收光谱等手段对制备的样品进行了物理表征,结果表明,在控制反应时间为1 h,介质p H值在1.14~9.01之间时,制备的样品为BiVO_4/Bi_6O_6(OH)_3(NO_3)_3复合物,当p H值增加至10.92时为纯BiVO_4;控制介质p H为7.17,反应时间在1~12 h之间时得到BiVO_4/Bi_6O_6(OH)_3(NO_3)_3复合光催化剂,反应时间为18 h时为纯BiVO_4.在可见光(λ≥400 nm)照射下,以有机染料罗丹明B(Rhodamine B,Rh B)为底物,研究不同条件制备的BiVO_4或者复合物为光催化剂的光催化特性,发现p H=7.17,水热反应12 h得到的催化剂(BiVO_4/Bi_6O_6(OH)_3(NO_3)_3)光催化降解活性高于对照制备的纯BiVO_4.同时在可见光照射下,BiVO_4/Bi_6O_6(OH)_3(NO_3)_3亦可以有效降解无色小分子2,4-二氯苯酚(2,4-Dichlorophenol,2,4-DCP),说明氧化过程涉及到光催化过程.分析BiVO_4/Bi_6O_6(OH)_3(NO_3)_3复合光催化剂对Rh B光催化降解过程中活性物种,表明在降解过程中主要涉及空穴和超氧氧化,O_2·~-起主要作用.

Synthesis and Visible-Light Photocatalysis Performance Research of BiVO4/Bi6O6(OH)3(NO3)3 Composite Photocatalyst

BiVO4 and BiVO4 /Bi6O6(OH)3(NO3)3 photocatalysts with different morphologies were synthesized hydrothermally by altering pH of the solution and reaction time. The samples molecular structure and morphologies were characterized by XRD, UV-Vis DRS and SEM. Firstly, a series of solutions were prepared from pH 1.17 to 9.01 and heated by controlling the reaction time at 1h. Pure BiVO4 was achieved at pH 10.92. Similarly, the reaction time was altered from 1-18h by controlling the solution pH at 7.17 and pure BiVO4 was achieved when the solution was heated for 18h. Results reveal that the preparation conditions affect the morphology, composition and photocatalytic efficiency with BiVO4 /Bi6O6(OH)3(NO3)3 prepared by heating the solution for 12 h at pH 7.17 display an enhanced efficiency than BiVO4 . The as-prepared samples show high photocatalytic activity for the degradation of RhB and 2,4-DCP during visible light irradiation. Appropriate radical and hole scavengers(h ) reveal superoxide radicals(O2.-) and photogenerated holes are produced in the reaction system. Superoxide radical is the dominant active species for the photocatalytic degradation of RhB.