摻雜碳之α-Fe2O3 薄膜合成及水分解應用

The syntheses of carbon-doped α-Fe2O3 thin films for water splitting

劉怡君(Yi-Chun Liu)

指導教授 ： 張裕煦

國立臺北科技大學/工程學院/資源工程研究所/碩士(2010年)

https://doi.org/10.6841/NTUT.2010.00096

摘要

本研究利用反應式磁控濺鍍系統成長三氧化二鐵薄膜 (α-Fe2O3)，主要探討不同碳摻雜量對三氧化二鐵薄膜物理特性及光電化學性質的影響及分析，使用石墨靶和金屬鐵靶在 O2 和 Ar 比例為 6：27 的電漿氣氛下分別進行濺鍍， 並在濺鍍時維持壓力為 2 m torr。
三氧化二鐵薄膜在製程中，利用 X 光繞射分析、X 光射線光電子能譜儀分析薄膜的結構及表面組成，以掃描式電子顯微鏡觀察薄膜的表面型態。當薄膜厚度為 100 Å 時，α-Fe2O3 光觸媒擁有最大光電流 0.65 mA。
在碳摻雜三氧化二鐵薄膜光觸媒方面，以改變石墨薄膜濺鍍厚度作為參數，濺鍍後於空氣和真空 2 種環境下熱處理，探討不同環境對碳摻雜產生的影響。利用紫外光 / 可見光吸收光譜量測薄膜在不同波長下的吸收，波長逐漸往可見光區位移，結構仍維持 α-Fe2O3 相摻雜後直接能隙為 1.8 到 2.0 eV 而霍爾量測發現載子濃度由 1.073×1014 增加到 4.807×1014。光電化學量測方面，以 1M 的 NaOH 水溶液作為電解液，最佳參數為真空下熱處理，碳薄膜厚度 5 Å 的α-Fe2O3試片。施加偏壓 0.7 V 時，光電流值增加為 1.2 mA/cm2，入射光光子轉換效率約 11.5 %，在 λ = 385 nm。穩定性測試可達 24 小時，產氫量為 5.3 mL (24 hr)。

關鍵字

綠能 ； 裂解水 ； 三氧化二鐵

並列摘要

In this study, the carbon-doped iron (Ⅲ) oxide films with various carbon concentration were deposited on fluorine-tin-oxide coated glass substrates by reactive direct current magnetron sputtering, where the deposition pressure was maintained at 2 m torr with a gas mixture of oxygen and argon at a mixing ratio of 6：27. To investigate the physical and photoelectrochemical properties of the α-Fe2O3 thin films.
The crystal structure and the surface composite of the α-Fe2O3 films were confirmed by XRD and XPS, respectively, and the surface morphology were observed by FESEM. When the thickness of the film is 100 Å, the maximum photocurrent of 0.65 mA is observed.
We investigated the effect of the carbon-doped iron oxide films which are annealed in atmosphere or vacuum with different sputtering time. It can demonstrated the shift of the carbon-doped iron oxide films by UV-Visible spectrum in various wavelength. It is maintained the α-Fe2O3 phase. However, the direct bandgap vaule is 1.8 to 2.0 eV in the carbon-doped iron oxide films. In the result of Hall effect, it can be observed that the charge concentration can increase from 1.073×1014 to 4.807×1014. In the photoelectrochemical measurement, it carried out in 1M NaOH solution, the flat band potentials of samples are at 0.7 V using Mott-Schottky measurement. The carbon-doped iron oxide film with carbon layer thickness 5 Å has the maximum photocurrent density that reached 1.2 mA/cm2 with external potential +0.7 V. The incident photon to current efficiency is about 11.5 %, at λ = 385 nm and the stable test reaches 24 hour. The photocatalyst H2 evolution rate reached 5.3 mL (24 hr).

並列關鍵字

green erengy ； water splitting ； α-Fe2O3

參考文獻

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