生物还原法制备Pd/TiO_2光催化剂

Preparation of Pd/Tio_2 Photocatalysts by a Bioreduction Method

用芳樟叶煮液将 PdCl_2还原成 Pd 单质纳米颗粒,将其沉积于 TiO_2上制得 Pd/TiO_2催化剂,采用X射线衍射(XRD),扫描电镜(SEM)和能量色散谱仪(EDS)对催化剂进行表征,并以甲基橙为目标降解物评价 Pd/TiO_2催化剂的光催化降解活性。结果表明,Pd/TiO_2催化剂中的 Pd 纳米颗粒的平均粒径小于10 nm,能够很好地分散在 TiO_2表面,且不改变 TiO_2锐钛矿的晶型结构。与未负载 Pd 的 TiO_2催化剂相比,Pd/TiO_2光催化剂对甲基橙有更高的光催化降解活性,能够提高甲基橙的降解速率。在实验范围内,Pd 与 TiO_2质量比为5%的催化剂活性最高,反应30 min 甲基橙就能完全降解,而空白 TiO_2催化剂在反应1h 时降解率只达到95%。Pd 与 TiO_2质量比为5%的 Pd/TiO_2光催化剂矿化率可达到96.2%,且重复使用仍能保持良好的催化活性。

Palladium nanoparticles was deposited on the surface of titanium dioxide for the preparation of the Pd/TiO2 photocatalysts by a novel bioreduction method. PdCl2 as the Palladium precursor was reduced to form Pd nanoparticles by the extract of cinnarnomum camphora leaf. The catalysts were characterized by X-ray diffraction （XRD）, scanning electron microscope （SEM） and energy dispersive spectrometer （EDS）. The photocatalytic degradation of methyl orange was used to test the photocatalytie activity of the catalysts. The results indicated that the average diameter of the Pd nanoparticles obtained by this bioreduetion method was less than 10 nm. The Pd nanoparticles were well dispersed on the surface of TiO2 without changing the anatase type of TiO2. Pd/TiO2 catalysts showed higher photocatalytic activity compared with blank TiO2 catalyst. The methyl orange degradation ratio of blank TiO2 catalyst in 60 rain was only 95%, however, catalyst with 5% mass ratio of Pd to TiO2 showed the highest activity in the experiment which could achieve complete degradation within 30 rain. 96.2% of mineralization was obtained in the case of the photodegradation by the catalyst with 5% mass ratio of Pd to TiO2, moreover, the photocatalytic activity of this catalyst did not decrease when it was used repeatedly.