二氧化鉿近年來受到微電子領域的注目，它有可能替代目前矽基集成電路核心器件金屬氧化物半導體場效應管（MOSFET）的柵極絕緣層二氧化矽（SiO2），以解決傳統 MOSFET 中 SiO2/Si 發展的尺寸極限問題。本實驗將二氧化鉿應用到全新的領域-光催化。我們發現二氧化鉿的缺陷能隙位置與五氧化二釩的導帶與價帶位置間有非常巧妙的關係，推測可以有效的分離五氧化二釩的電子電洞對。因此透過結合五氧化二釩與二氧化鉿，來嘗試提升光催化降解汙染物的能力。在實驗中，我們在不同的酸鹼度下結合五氧化二釩與二氧化鉿，來了解在不同酸鹼度下製作的二氧化鉿氧空缺是否在濃度或位置上有變化。同時也改變五氧化二釩的形狀來增加接觸面積，增加與污染物接觸的機會。本實驗大致上分為兩大類，第一類為以商用的五氧化二釩顆粒與不同比例且在不同酸鹼度下製作的二氧化鉿結合，第二類為改變商用的五氧化二釩顆粒樣貌成為奈米線，之後再與不同比例的二氧化鉿結合。之後兩大類的實驗均有針對光催化效率的進一步研究。
實驗中使用了X射線繞射儀、掃描式電子顯微鏡與穿透式電子顯微鏡去分析其結晶結構、表面形貌。使用表面吸附儀量測不同樣貌的五氧化二釩比表面積，表面化學鍵結分析確認五氧化二釩的不同價數存在是否影響光催化的結果。光學性質的分析，使用可見光/紫外光光譜儀量測純的五氧化二釩以及與二氧化鉿結合後的樣品之光吸收能力，使用微拉曼及微光激發光譜儀分析電子電動可以移動的能階位置與再結合速率。最後透過太陽光模擬器與紫外光來測定不同樣品對於分解亞甲基藍的效率。

A V2O5-HfO2-X composite photocatalyst consisting of one-dimensional high crystallinity V2O5 nanowires with surface HfO2 nanoparticles and zero-dimensional high crystallinity V2O5 nanowires with surface HfO2 nanoparticles are reported. The V2O5 nanowires and HfO2 nanoparticles were synthesized using a microwave hydrothermal method and sol-gel method, respectively. V2O5 has band gap of 2.3 eV, which absorbs visible light. The HfO2 nanoparticles were made to exhibit oxygen defect so that a sub-band structure occurs under the conduction band. We show that such a sub-band energy level help to retard the recombination of electron-hole pairs. The obtained results show that the degradation of methylene blue using V2O5-HfO2-X composite is much better than that using pure V2O5 nanowires under both UV and visible light irradiations. The effects of the composite composition and the oxygen defect in HfO2-x on the catalytic performance has been addressed.

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