| 摘要: | 電解水產生氫氣及氧氣的反應，最近這些電化學的過程被熱烈地被討論，如果能有效率的產生氫氣，未來世界或許可以建設在以氫為主的一清靜健康的社會。以產氫反應而言，酸鹼水溶液各有利弊，雖然在酸中，產氫可以有較低的過電位或有比較高的效率，但必須要用貴重金屬作為催化劑，導致高昂的成本，而非貴重金屬在酸中不穩定，無法適用。在鹼中可以非貴重金屬例如銅鎳等作為催化劑，此一題目已經被廣泛的研究報導，若干材料展現比鉑電極更好的特性，但穩定性似乎是比需要改善的課題。針對這些要克服的困難，明顯的我們需要一些檢測技術來更深入的分析這些電化學過程。本組已經利用掃描探針顯微技術來研究電化學界面，在許多場合可以獲致原子或分子的解析度，因此可以更深入了解電化的介面。同時我們的工具箱中添加了一個新工具—紅外吸收光譜儀,它有助於識別電極上的有機分子例如甲醇或乙醇的吸附。鉑以其對許多電化學的電活性而聞名，例如氫氧產生、甲醇氧化和氧還原反應等一系列電化學反應，這些氧化還原反應對燃料電池的運行至關重要。然而, 鉑金屬的高成本是發展燃料電池商業化的主要障礙之一。因此, 減少電催化劑中的鉑用量或尋找廉價的催化劑是繞過這一障礙的主要策略。除了電催化劑的化學成分外, 電催化劑表面的原子排列也會影響其活性，但如何暴露一最好的晶面是現今的納米金屬粒子的製備及其催化活性的研究重要課題。銅電極以其獨特的二氧化碳還原及甲醛氧化的催化特性，最近受到許多的關注，我們設計在實驗室內利用氫氣火焰槍既可製備銅單晶珠電極的方法，以此研究人員可自行製作出具有明確結構的銅電極，此一方法可以改良以製備合金電極，例如銅鎳合金，此一電極(1%鎳)促使甲醛的氧化率提高12倍，應可用於甲醛燃料電池的陽極。此發現展現雖然鎳本身對甲醛的氧化沒有活性，但參入銅材質後，發揮很大的作用，我們將繼續探索銅及其合金電極的電化學特性和電催化。利用電化學及表面分析技術研究能源相關的議題，特別是電解水產生氫氧氣及有機小分子的氧化反應，希望能對電極的介面結構及重要的反應機制有更深入的了解，進而能製備更有效的電催化材料。 ;It is no doubt that earth has suffered from the excessive uses of fossil fuels for decades, causing severe and irreversible damages to the environment and weather of this planet. To find new energy sources for the future to replace the conventional fossil fuel is an urgent issue. Solar cells and fuel cells are identified as two of most feasible candidates for the future. In particular, hydrogen is recognized as the cleanest fuel. Also, hydrogen is produced traditionally by gas water shift reaction, which can be contaminated with carbon monoxide. Recently, it is shown the electrolysis of water can produce hydrogen in acidic and basic electrolytes. This idea has been pursued for several decades and some promising results are reported. For having a stable operation of these cells, it is inevitable to have noble transition metals such as Pt as the catalyst at the anode and cathode. The scarcity and high cost of Pt could lead to unaffordable cells. Besides pure Pt catalyst might not be the optimal choice of the needed catalyst. In contrast, non-precious metals such as Cu and Ni can be used as the catalyst in a basic environment, but the overpotentials of the desired reactions can be higher, leading to poorer efficiency in the conversion from electrochemical to chemical form of energy. Many methods have been used to probe the interfacial processes of electrolysis of water to hydrogen and oxygen. From the fundamental perspective, the key issue in the fundamentals of all research has been the need to understand the reactive sites of these reactions on the electrode. This subject needed to be approached by techniques capable of obtaining information in the course of reaction or in the “operando” conditions. Arguably, only a few techniques are possible to work under these conditions, including Raman spectroscopy and X-ray absorption spectroscopy. Meanwhile, scanning tunneling microscopy (STM) has been used to extensively study the electrified interface, particularly platinum under various conditions. Here it is proposed that STM imaging is used to reveal the structural aspects of Pt and other relevant electrodes in electrocatalysis. |
