Nanoporous iridium electrodes are prepared and electrochemically investigated towards the water oxidation (oxygen evolution) reaction. The preparation is based on ‘anodic’ aluminum oxide templates, which provide straight, cylindrical nanopores. Their walls are coated using atomic layer deposition (ALD) with a newly developed reaction which results in a metallic iridium layer. The ALD film growth is quantified by spectroscopic ellipsometry and X‐ray reflectometry. The morphology and composition of the electrodes are characterized by scanning electron microscopy, energy‐dispersive X‐ray spectroscopy, and X‐ray diffraction. Their catalytic activity is quantified for various pore geometries by cyclic voltammetry, steady‐state electrolysis, and electrochemical impedance spectroscopy. With an optimal pore length of L≈17–20 μm, we achieve current densities of J=0.28 mA cm⁻² at pH 5 and J=2.4 mA cm⁻² at pH 1. This platform is particularly competitive for achieving moderate current densities at very low overpotentials, that is, for a high degree of reversibility in energy storage.

中文翻译：

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基于原始原子层沉积的有序纳米多孔铱电极的高度可逆水氧化

制备纳米多孔铱电极并针对水氧化（析氧）反应进行电化学研究。该制剂基于“阳极”氧化铝模板，可提供直的圆柱形纳米孔。它们的壁采用原子层沉积（ALD）和新开发的反应进行涂层，从而形成金属铱层。ALD 薄膜的生长通过椭圆偏振光谱仪和 X 射线反射仪进行量化。通过扫描电子显微镜、能量色散X射线光谱和X射线衍射对电极的形貌和成分进行了表征。通过循环伏安法、稳态电解和电化学阻抗谱对各种孔隙几何形状的催化活性进行了量化。最佳孔径长度为L ≈17–20 μm，我们在 pH 5 时实现J =0.28 mA cm ^{-2的电流密度，在 pH 1 时实现}J =2.4 mA cm ^{-2 的}电流密度。该平台在实现中等电流密度方面特别具有竞争力在非常低的过电势下，即能量存储的高度可逆性。