本研究為探討鉑改質二氧化鈦在可見光下活性來源，針對兩種不同的二氧化鈦，兩相組成的P25與Anatase相的ST-01 進行鉑改質程序，P25與ST01兩者皆具有較大的能隙值而限制其可應用的激發波長範圍，且光催化反應屬於觸媒表面的化學反應機制，因此藉由Pt表面改質的方式，以提高可見光與紫外光下的反應活性。
藉由物性的分析，如UV-Vis量測樣品改質後能隙值的變化、PL分析電子電洞對的再結合速率、TEM觀察觸媒表面的形態以及藉由XPS分析Pt的價態，並以液相甲基橙降解與氣相氮氧化物氧化反應來探討其光催化活性。
實驗製備是採用光沉積(photodeposition)的改質方式，比較調整不同的pH值、甲醇的效應以及Pt含量的影響；pH值不僅改變二氧化鈦的等電點，也影響了的Pt陰離子的水解程度，進而改變Pt在二氧化鈦表面的粒徑以及價態；甲醇在反應中則扮演了電洞捕捉者的角色，影響Pt的還原程度；增加Pt的含量則可以提高光催化的活性，然而當含量過多時則造成了活性點被遮蓋，或形成了電子電洞的再結合中心。
由於Pt具有三種不同的價態，Pt(0)、Pt(II)以及Pt(IV)，實驗結果得到Pt改質二氧化鈦後若以Pt(0)的價態存在，則具有較低的能隙值，以及較長的可見光吸收範圍，然而光催化的活性卻不佳；其中PtOx具有較好的光催化效率。
在較低的pH值以及未添加甲醇的製備條件下，H2PtCl6在Anatase表面形成了金屬PtOx以及離子鍵結的PtCl4，藉由PtCl4其本身的光敏化特性，與Anatase兩者介面間的電子電洞傳遞機制，可以有效的抑制其再結合速率，提高在可見光死紫外光下的應答特性。比較不含氯的Pt前驅物(H2Pt(OH)6)，明顯的Cl為影響光催化活性很重要的因素。

This work focused on the visible-light-responsively photoactivity of platinized TiO2 and the rational mechanism. Two commercially available TiO2-catalysts, P25 and ST01, were used as raw materials for platinized modification. The modified area was controlled on TiO2 due to the photocatalytic reaction rate was carried out on its surface. Thus, a proper Pt-modification on TiO2 can enhance its photoactivity under both visible and ultraviolet illuminations.
Physic characterization of Pt-modified TiO2 samples, including band gap shift, charge carriers recombination rate, surface morphology, and Pt valence state were identified using UV-visible absorption spectra, photoluminescence, transmission electron microscopy, and X-ray photoelectron spectrum analysis. The photocatalytic activities of the synthesized photocatalysts were evaluated for the oxidation of NOx and decolorization of dye under illuminations by UV and visible light.
The Pt-modified TiO2 was prepared by photodeposition method with using H2PtCl6 as precursor. Effects of preparation parameters, pH value, presence of methanol, and amount of Pt, on photoactivity and platinum valence state were invertigat in detail. The isoelectric point of TiO2 and hydrolysis of Pt anion were affected by pH value, resulting in the Pt particle size and valence state on TiO2 surface. The photoreduction rate increased with the presence of methanol due to it was the hole-scavenger. An optimal Pt-loading content (0.5 mol%) was resulted from the competitions among effects of visible-light active site, coverage, and carriers recombination rate.
Various state of platinum, Pt(0), Pt(II), and Pt(IV) were generated on the TiO2 surface in the photodeposition process. The experiment result indicated that the Pt(0)-modified TiO2 exhibits the smallest band gap, but the PtOx-modifed TiO2 has the better photocatalytic activity than the former. In the photodeposition procedure, PtOx and PtCl4 were produced using lower pH value, absence of methanol, and H2PtCl6 as precursor. Results depicted that PtCl4 plays two roles: it acts as a sensitizer for visible-light absorption on the anatase surface, and as an electron trapper to suppress the charge carrier recombination rate. It thus enhances photocatalysis activity under UV and visible illuminations. The effect of chloride ion on visible-light response was further elucidated using H2Pt(OH)6 as the comparative precursor.

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