现代社会使用的能源载体主要为不可再生的化石燃料,为了人类社会的永续发展，必然要寻求其他的化石能源替代品。由于氢气具有无毒、高热值和产物清洁等特点，故广泛被认为是最具潜力的选项。然而，现今氢气的来源又多由化石来源加工而成，为了达成对化石燃料的替代，自然需寻求其他手段制氢。在众多清洁制氢方式中，电解水制氢最具应用前景，但其析氧反应所带来的高过电位是瓶颈之一，造成了输入电压高，使得耗能巨大，阻碍电解水制氢技术发展，需要研制良好的催化剂以克服。电解水制氢有许多技术路线正在开发中，其中大多数的析氧反应在碱性环境中进行。为制备出在碱性环境中具有高活性和高稳定性的析氧反应催化剂，本文围绕泡沫镍铁合金，利用其具有双金属元素及高比表面积的特点，以其作为自支撑催化电极的基底，以水热反应硒化法和酸蚀反应法制备出两种析氧催化电极，FeOOH@NiFeSe@NiFe 和 NiFe LDH@NiFe。并以 LSV、EIS 及 CV 等测试方法确定其电化学性能，又以拉曼光谱、XRD、XPS、SEM 及 TEM 等测试方法表征其材料形貌、构成和长期运行后的变化。在 1 M KOH，10 mA cm-2 电流密度的条件下，FeOOH@NiFeSe@NiFe 过电位为 224 mV，Tafel 斜率为 52.67 mV dec-1。NiFe LDH@NiFe 过电位为 201.18 mV，Tafel 斜率为 48.52 mV dec-1，在同类材料中性能皆属于前列。两者均可完成 25 小时的稳定性测试，且两者的催化性能均来自于材料的本征催化活性提升。运行析氧反应后，FeOOH@NiFeSe@NiFe 出现了组成与结构的变化，而 NiFe LDH@NiFe 则仍能完整地维持原形貌与组分。本文所述之两种析氧催化电极皆以泡沫镍铁合金自身作为铁源和镍源，实现催化剂的自源生长，再加上自支撑结构的特性，因此保证了电极的稳定性。加之，受惠于自源生长，使得两者皆有合成步骤少的优点。其中又以 NiFe LDH@NiFe 由于溶液浸泡酸蚀法易于工程放大，且酸蚀溶液组分价格低廉，使其更加具有进一步在工业规模中用于电堆的析氧侧电极的潜力。总体而言，本文证明了以泡沫镍铁合金作为基底与铁镍源，可以经由步骤简单的反应而形成具有高活性与高稳定性的自支撑析氧催化剂，对电解水制氢技术及其碱性析氧催化剂的发展具有启发性意义。
Modern world greatly depends on fossil energy resources. In order to achieve sustainable development, substitutes for fossil energy resources are certainly needed. Hydrogen is widely considered as a future energy carrier because of its favorable properties. Nevertheless, fossil resources dominate current hydrogen production, so other means of hydrogen production is required. Being one of the most promising method, hydrogen generation by water electrolysis is still on a small scale. One of its problem is the high overpotential of the oxygen evolution reaction (OER). It causes the high working voltage, and further makes the energy consumption high. Hence, developing electrocatalyst with excellent catalytic performance is vital for addressing this issue. There are different processes of water electrolysis, and most of their OER are conducted in alkaline condition. In order to produce OER catalysts with high performance and stability in alkaline condition, this work focuses on NiFe foam. Benefiting from its bi-metal element sources and high specific surface area, NiFe foam was implemented as the substrate of the electrode. Hydrothermal selenizing method and acid solution corrosion method were respectively applied to produce FeOOH@NiFeSe@NiFe and NiFe LDH@NiFe. Their electrochemical performance was tested by LSV, EIS and CV, and they were further characterized by Raman spectra, XRD, XPS, SEM and TEM.Under the condition of 1 M KOH solution and 10 mA cm-2 of current density, FeOOH@NiFeSe@NiFe shows the overpotential of 224 mV with a Tafel slope of 52.67 mv dec-1, and NiFe LDH@NiFe shows the overpotential of 201.18 mV with a Tafel slope of 48.52 mV dec-1. They both belong to the leading group of its similar counterparts, and their catalytic performance principally stems from the intrinsic improvement of the materials. Besides, both of them can stand a 25-hr stability test. After the stability test, FeOOH@NiFeSe@NiFe undergoes some structural and componential changes, while NiFe LDH@NiFe stays almost the same as before.Thanks to the self-supported design of the catalyst and the autologous growth brought about by using NiFe foam as nickel and iron sources, the stability of the electrode is ensured. Additionally, the autologous growth makes both of their synthesis very simple. In particular, because of the scalability of the acid solution corrosion method and the low price of the solution components, NiFe LDH@NiFe is extraordinarily competent for industrial application.On the whole, this thesis has proven that by using NiFe foam as substrate, stable and high-performance self-supported OER catalysts can be produced by facile processes. This work greatly inspires the development of hydrogen production by water electrolysis and OER electrocatalysts in alkaline environment.
