雙金屬改質二氧化鈦提升亞甲基藍降解之研究

本研究利用溶膠-凝膠法(sol-gel method)配合隔水加熱法(hydrothermal treatment)對二氧化鈦(titanium dioxide, TiO2)光觸媒進行兩階段改質，分別為摻雜(doping)過渡金屬銅(Cu)、鐵(Fe)之單金屬改質二氧化鈦光觸媒後，更進一步沉積(deposition)銀(Ag)而得到雙金屬改質二氧化鈦光觸媒。經SEM及TEM分析結果可發現經本研究雙金屬改質前後之二氧化鈦光觸媒，大致上粒徑為20~30 nm之圓形顆粒；由XRD分析結果可知，沉積於光觸媒表面的銀有零價銀(Ag0)的晶相存在，而二氧化鈦光觸媒皆以銳鈦礦相存在；界達電位分析結果，Ag(10 wt%)/Cu(0.01 %)-TiO2、Ag(10 wt%)/Fe(0.01 %)-TiO2、Cu(0.01 %)-TiO2、Fe(0.01 %)-TiO2及TiO2之等電位點pHiep分別為5.1、4.8、6.3、5.5、7；UV/vis分析結果指出，本研究摻雜單一金屬改質二氧化鈦光觸媒，其臨界波長(band edge wavelength)較未改質二氧化鈦些微提高，而雙金屬改質二氧化鈦光觸媒之臨界波長則有大幅的提升對可見光的吸收能力也明顯地增加。本研究雙金屬改質二氧化鈦可見光光催化效率明顯高於單一金屬摻雜改質與未改質二氧化鈦，在430 nm藍光照射下光催化亞甲基藍10分鐘內可達脫色率100 %，相較於單金屬(銅、鐵)改質二氧化鈦之(18小時)脫色率分別為34 %及31 %及未改質之二氧化鈦有顯著的提升。在三種可見光光源照射下，雙金屬改質二氧化鈦光觸媒光催化降解亞甲基藍之效率隨著光源波長的提高而明顯降低，降解率依序為430 nm藍光>LED藍光>LED黃光。

關鍵字

二氧化鈦；可見光； LED ；雙金屬改質；亞甲基藍

並列摘要

In this study, we developed binary metals modifying titanium dioxide with two steps by using sol-gel method and hydrothermal treatment. In order to doped the transformation metal Cu and Fe in the lattice of TiO2. And then deposition the noble metal Ag it. In the result of SEM and TEM, the grain size of about 20~30 nm. After XRD analysis, the silver deposition on the surface of Photocatalyst might be Ag0. All the TiO2 was existed as anatase. The result of Zeta potential shows that the surface charge on the all kinds of TiO2 in this study was decreased with the increasing of pH, and the pHiep of Ag(10 wt%)/Cu(0.01 %)-TiO2, Ag(10 wt%)/Fe(0.01 %)-TiO2, Cu(0.01 %)-TiO2, Fe(0.01 %)-TiO2 and TiO2 was 5.1、4.8、6.3、5.5 and 7. In the result of Uv/vis analysis, the band edge wavelength of doping modifying TiO2 was higher than pure TiO2, and the visible light absorption of the binary metals modifying TiO2 was increased obviously. In this study, the photocatalytic efficiency of binary metals modifying TiO2 was higher than doping modifying TiO2 and pure TiO2 plainly. Under the visible light of 430 nm irradiation, the decolorization rate of Methylene Blue was 100 % in 10 minute by using binary metals modifying TiO2. Under the same light source the decolorization rate of Methylene Blue was 34 % and 31 % in 18 hours by using Cu or Fe doping TiO2. Under three kinds of visible light source irradiation, the photocatalytic efficiency to MB of binary metals modifying TiO2 increased with the decreasing of light source wavelength as 430 nm blue>LED blue >LED yellow.