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標題: Synthesis of nano-structured TiO2 film by anodic oxidation
作者: 楊于紹
Yang, Yu -Shao
關鍵字: Titanium dioxide;二氧化鈦;anodic oxide films;nano;electrochemical;陽極氧化膜;奈米;電化學
出版社: 材料工程學研究所
本研究主要是以強鹼性鹼金屬溶液(如KOH)為電解液,用掃描電壓的鍍著模式,在室溫下數分鐘,即可在鍍鈦異質基材上,製備出奈米結構之二氧化鈦薄膜。由場發射掃描式電子顯微鏡分析的結果顯示,在室溫1 M KOH的電解液中,以掃描電壓模式進行陽極氧化:速率為10 mV/s,截止電壓為3 ~85 V時,即會產生奈米網狀結構,其網環平均大小約50 nm,網線寬約10 nm以下。另經拉曼光譜分析,掃描截止電壓為20 ~85 V時,會出現明顯單一銳鈦礦(anatase)相之二氧化鈦能峰。而此奈米網狀結構二氧化鈦膜厚可達250 nm。此奈米網狀結構,經500℃熱處理,可生成熱力學穩定之單一金紅石 (rutile)相二氧化鈦,而網狀結構不致被破壞。再者對照硫酸的電解液,以掃描電壓模式進行陽極氧化:速率為3 mV/s,截止電壓為10 V到60 V時,則可產生奈米顆粒狀結構,顆粒大小在10 nm以下,晶體結構亦為銳鈦礦相之二氧化鈦,膜厚可達80 nm。

Nano-structured titanium dioxides exhibiting their high specific surface area, excellent electronic and optical properties have many applications, including photocatalysis, dye-sensitized solar cell, superior and biocompatible applications, etc. This study employed electrochemical anodic oxidation to synthesis nano-structured titanium dioxide films on different substrates, especially on heterogeneous substrates, such as silicon wafers and polymers. It is noteworthy that the pre-deposition of titanium film is one of the requirements for heterogeneous substrates. This novel processing is clearly fit into the main stream of nanotechnology.
Anodic oxidation was performed by using linear sweep voltammetry mode at room temperature in highly alkaline electrolytes, such as KOH. Field-emission scanning electron microscopy results show that nano-network structured titanium dioxides films were successfully fabricated on Ti-coated Si wafers within several minutes with scanning cutoff voltages ranging from 3 to 85 V (scanning rate: 10 mV/s) in 1 M KOH electrolytes. The inner diameter of the nano-network rings is about 50 nm and the ring width is less than 10 nm. Raman spectroscopy results show that single anatase TiO2 phase was present with scanning cutoff voltages ranging from 20 to 85 V. The thickness of nano-network TiO2 films could reach as high as 250 nm. After annealing at 500℃, the obtained anatase phase could be fully transformed to rutile phase without breaking the nano-network structure. When H2SO4 electrolyte was used, nano-particle structured titanium dioxides films were formed with scanning cutoff voltages ranging from 10 to 60 V (scanning rate: 3 mV/s). The mean particle size is less than 10 nm and the resultant crystal structure is anatase TiO2. The thickness of nano-particle TiO2 films could reach as high as 80 nm.
This TiO2/Ti/substrates sandwiched structure possesses superior adhesion behavior and the titanium film could also prerent the substrates from being determined by the photocalytic reaction. Above all, nano-structured TiO2 could be prepared within only several minutes on many different substrates. This process has enormous potential applications.
Appears in Collections:材料科學與工程學系

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