利用表面錯合模式理論探討氧化鐵光電極單原子催化劑的組裝機制

Using Surface Complexation Modeling on Preparation of Single-Atom Catalyst on Hematite Photoelectrodes

洪薪婷(Hung, Hsin Ting)

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(2015年)

摘要

表面錯合理論在傳統上被用在環境科學領域以模擬和解釋基於熱力學平衡常數通過化學計量反應的微粒表面和汙染物離子之間之相互作用，此研究報告應用表面錯合理論操控在赤鐵礦表面上的鈷單原子助催化劑，穿透式電子顯微鏡圖像證實調整pH值和鈷離子濃度會導致鈷催化劑在赤鐵礦表面的均勻分布或粗大顆粒的簇團，這與模擬結果一致，這是由於鈷吸附或沉澱在赤鐵礦表面，鈷在表面的不同分布情況進一步影響有機染料(羅丹明B)光降解的反應性和光電化學的水氧化反應，此外，當應用表面錯合模型使鈷-磷 (Co-Pi)助催化劑裝飾在赤鐵礦電極上時，發現磷酸根在增強光電化學表現上也扮演著重要作用，這是因為表面的磷酸根可誘導Co-Pi助催化劑變成連續或中孔結構層，導致後者比前者擁有更高的光電流表現，此研究結果表明，應用表面錯合模型不僅可以操控助催化劑在赤鐵礦表面上的分布，且還可以探討表面分布情況與赤鐵礦電極光催化活性的界面現象。

關鍵字

氧化鐵 ； 光催化劑

並列摘要

Surface complexation modeling (SCM) has been wildly applied in the field of environmental science to simulate and explain the interaction between particulate surfaces and pollutant ions via a stoichiometric reaction based on the thermodynamics. We report herein the application of SCM to manipulate the dispersion of cocatalysts on the surface of hematite. In the preliminary trial in a backer system, observations from TEM images confirm that the pH and loaded Co2+ concentrations lead to either homogeneous distribution or coarse clusters of cobalt cocatalysts on hematite surfaces, which is consistent with our SCM simulation. This can be attributed to adsorption or precipitation of cobalt on the hematite surface. Different distribution of surface cobalt cocatalysts further influence the reactivity of photodegradation of organic dyes (RhB) and photoelectrochemical (PEC) water oxidation. Furthermore, when SCM was applied to decorate hematite electrodes with cobalt-phosphate (Co-Pi) cocatalysts, it was found that Pi also plays an important role in the enhanced PEC performance. This is because surface Pi might induce Co-Pi cocatalysts developing into either a continuous or a mesostructured layer, leading to the latter has the photocurrent two folds higher than the former. Our results substantially demonstrate that the application of SCM can not only manipulate the dispersion of surface cocatalyst on hematite surface but also provide an opportunity to explore the interface phenomenon of this distribution and consequential photocatalytic reactivity of hematite electrodes.

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