扩孔金属有机骨架UiO-66的制备及其光催化还原六价铬性能

Preparation of expanded metal organic framework UiO-66 and its photocatalytic reduction of hexavalent chromium

金属有机骨架孔径较小(1~2 nm),在水处理中应用受到了很大的限制。针对这一问题,采用水热法,利用十二烷酸作调节剂对UiO-66进行扩孔,制备了微孔-介孔UiO-66(HP-UiO-66),并通过X射线衍射、透射电子显微镜、漫反射光谱和比表面积测试等对其进行了系统表征。结果表明,加入调节剂后,成功地将UiO-66的孔径由1.68 nm扩大至4.29 nm;反应210 min后,扩孔后的UiO-66光催化还原六价铬的效率为99.9%,与UiO-66相比,其光催化还原六价铬的效率明显提高。光催化效率提高归因于扩孔使催化剂内部的活性点位得以利用,并且改性后的UiO-66的光吸收带边发生了红移,能产生更多的光生电子,从而光催化还原性能得到了提高。

The application of MOFs in water treatment has been greatly restricted due to its small pore size(1-2 nm).To solve this problem,microporous-mesoporous UiO-66(HP-UiO-66)was fabricated by the hydrothermal method using dodecanoic acid as a regulator.The sample was characterized by X ray diffraction,transmission electron microscope,diffuse reflection spectroscopy and specific surface area tests.The results showed that the pore size of UiO-66 was successfully enlarged from 1.68 to 4.29 nm after adding the regulator.After 210 min illumination,the photocatalytic reduction ratio of Cr(Ⅵ)by UiO-66 after expansion was 99.9%.The photocatalytic reduction efficiency of Cr(Ⅵ)was significantly improved compared with the UiO-66 sample which not been enlarged pore size.The enhanced photocatalytic reduction ability could be attributed to the availability of active sites in the pore after pore expansion.And the red-shifted band gap edge could help expanded pore UiO-66 absorb more light and generate more electrons,which ultimately elevate the photocatalytic reduction ability.