本研究係以沉澱法來製備二氧化鈰(CeO2)粉體，旨在探討以雙氧水(H2O2)為氧化劑之沉澱反應及其產物特性。研究中改變雙氧水加入之時間點、雙氧水濃度、反應溫度及鈰前驅鹽價數等製備變因，探討其對所得CeO2粉體之晶粒大小、形狀、晶態、比表面積及催化活性等性質之影響，並藉由粒子之演化過程探討粉體形成之機制。
實驗結果發現，在反應過程中，H2O2之添加時間CeO2產物之性質影響頗鉅，在沉殿前加入H2O2，所得產物為小於5nm之粒狀粉體；若沉澱開始後才加入，產物則呈棒狀，且其直徑小於20nm。
當反應溫度為90℃時，隨著H2O2濃度之增加，產物由粒狀晶形逐漸轉為棒狀晶粒，且棒狀/粒狀比例隨著H2O2濃度之增加而增大。添加H2O2所得產物之比表面積遠大於未添加者。另外，唯當反應溫度高於50℃時，才有棒狀晶形出現，否則產物為粒狀。
進一步，以煅燒後之CeO2作為觸媒進行CO氧化反應。結果發現添加H2O2所得CeO2之催化活性較未添加者高，且此活性隨H2O2濃度之增高而增大，此結果與H2-TPR結果相吻合。
比較以Ce(Ш)或Ce(Ⅳ)為前驅鹽之最終產物發現，以前者所得產物之棒狀比例較高，而後者所得產物含有極小晶粒，故具有較大之比表面積。
由產物粒徑演化推測，H2O2在反應中扮演氧化劑之角色，提升氧化速率。更重要的是，由於產生大量過氧基(OOH-)及羥基(OH-)與Ce3+作用形成中間產物而降低CeO2晶粒成長，因此產物粒徑小且具高比表面積。

Cerium dioxide (CeO2) powders were synthesized with adding hydrogen peroxide (H2O2) by the precipitation technique. The investigation of precipitation reaction and properties of products were emphasized in this work. Experimentally, the precipitation reactions were performed under various adding time of H2O2, H2O2 concentrations, reaction temperatures, and valences of cerium precursors. The effects of preparation conditions on the particle size, shape, crystalline structure, surface area and catalytic activity of final CeO2 products were investigated. Moreover, the formation mechanismof CeO2 particle was also discussed via the particle evolution.
The experimental results revealed that, the addition of H2O2 in the precipitation showed great influences on the properties of CeO2 products. As the H2O2 was added prior to the precipitation, the product was particulate powder with a size smaller than 5 nm. However, if H2O2 was added after the precipitation reaction started, the CeO2 product became rodlike shape with a size smaller than 20 nm.
At reaction temperature of 90oC, as the H2O2 concentration was increased, the shape of resulting CeO2 product changed from fully particulate into partially rodlike. In other words, the rodlike/particulate ratio of product was increased with increasing the H2O2 concentration. With the presence of H2O2, the surface area of the product was larger than that without adding H2O2. Besides, rodlike CeO2 powders came out in the final product only at temperature above 50oC; otherwise the product shaped particulate.
The catalytic oxidation of carbon monoxide (CO) was carried out over the calcined CeO2 powders. As compared with the CeO2 powders prepared without H2O2, the catalytic activity of those with H2O2 was much higher, and it was increased with the increase of H2O2 concentration, which was in a good agreement with the TPR results.
To make a comparison between products obtained from Ce(III) and Ce(IV) precursors, it revealed that the former had higher rodlike/ particulate ratio. Nevertheless, the later comprised of many tiny particles exhibited larger surface area.
From the particle evolution of CeO2 powers, it was inferred that, the hydrogen peroxide played a role of oxidizing agent in the precipitation reaction, with which the oxidation rate was accelerated. More importantly, it could provide a large numbers of peroxy (OOH-) and hydroxyl(OH-) species complexing with cerium to form Ce intermediates. This retarded the grain growth of CeO2, resulting in the small size and large surface area of the final product.

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