以檸檬酸添加於電鍍法中簡易製備高光電化學效率的碳包覆赤鐵礦光陽極

Facile synthesis of enhanced photoelectrochemical performance of carbon coated hematite photoelectrodes via electrodeposition with citric acid additive

陳以諾(Chen,Yi Nuo)

指導教授 ： 王竹方

國立清華大學/原子科學院/生醫工程與環境科學系/碩士(1921年)

摘要

中文摘要
本篇利用簡易方便的電化學方法合成出一種被碳層包覆的赤鐵礦奈米結構可利用於太陽能產氫，這是首次利用電鍍方法製備出這種有碳層包覆的赤鐵礦，我們研究利用檸檬酸當作碳源去合成奈米結構的α-Fe2O3薄膜會如何影響薄膜的結構跟它的光電化學性質。首先，我們了解鐵離子跟檸檬酸間的螯合確實明顯改變了鐵錯合物種的分布相較於沒有檸檬酸添加的環境，然後在鹼性環境中電鍍時,發現檸檬酸的添加確實大大有助於光電流的增加，從電子能譜儀(XPS)發現在284 eV有強烈的碳訊號，這同時也與穿透式顯微鏡(TEM)的結果相符合，這種從cit-Fe 系統獲得的碳包覆赤鐵礦薄膜的光電流會隨著合成時的pH值上升而上升，最多可在pH8時達到2.1毫安培的光電流，電化學交流阻抗頻譜顯示出相較於沒有碳參雜的而言，這種碳參雜的薄膜具有更高的載子濃度,這也是它高度光催化性的原因，這種簡單和便宜的方法可以被輕鬆的大量製備為高效率太陽能水產氫的實際應用奠定基礎。

關鍵字

電鍍 ； 赤鐵礦 ； 水產氫 ； 碳包覆 ； 檸檬酸

並列摘要

Abstract
Here we introduce a facile synthesis of carbon-coated hematite nanostructures for solar water splitting via a simple electrochemical methods. This is the first time the synthesis of carbon-coated hematite being reported via electrodeposition. We investigate the structure and photoelectrochemical effects of adding citric acid as carbon source to synthesize nanostructured α-Fe2O3 thin films. Firstly, we know that the chelation between ferric ions and citric acid significantly changes the distribution of ferric species in comparison with that without any citric acid additives. The addition of citric acid greatly enhanced the photocurrent when the electrodeposition was conducted in the alkaline environment. The data of XPS clearly shows a strong C signal appearing at 284 eV, which is in a good agreement with the TEM results. The photocurrent of carbon-coated hematite films obtained from cit-Fe system increases with increasing pH, reaching a maximum photocurrent around 2.1 mA at pH 8. Electrochemical impedance spectroscopy revealed that C doped films have higher donor density than that of undoped film,which is responsible for high photoactivity. The simple and cheap method could be scaled up easily which may pave the way for the practical application for efficient solar water splitting.

並列關鍵字

electrodeposition ； hematite ； water splitting ； carbon-coated ； citric acid

參考文獻

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