Aerogels are a very interesting group of materials owing to their unique physical and chemical properties. In the context of electrocatalysis, the focus has been on their physical properties, and they have been used primarily as catalyst supports so far. In this work, we synthesized porphyrin aerogels containing Ni and NiFe mixed metal materials and studied them as catalysts for the oxygen evolution reaction (OER). Different Ni : Fe ratios were synthesized and studied in electrochemical cells, and DFT calculations were conducted in order to gain insight into their behavior. The activity trends were dependent on the metal ratios and differ from known NiFeOOH materials due to the change in the oxidation states of the metals to higher numbers. Herein, we show that Ni and Fe have a synergistic effect on the OER, despite being structurally separated. They are connected electronically, though, through a large organic aromatic system that facilitates electron sharing between them. Among the mixed metal porphyrin aerogels, the best ratio was found to be Ni : Fe = 35 : 65, in contrast to oxide/oxyhydroxide materials in which a ratio of 80 : 20 was found to be ideal.

中文翻译：

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NiFe-混合金属卟啉气凝胶作为碱性电解槽中析氧反应的催化剂

气凝胶是一组非常有趣的材料，因为它们具有独特的物理和化学性质。在电催化方面，重点一直放在它们的物理性质上，到目前为止，它们主要用作催化剂载体。在这项工作中，我们合成了含有 Ni 和 NiFe 混合金属材料的卟啉气凝胶，并将其作为析氧反应 (OER) 的催化剂进行了研究。在电化学电池中合成和研究了不同的 Ni:Fe 比率，并进行了 DFT 计算以深入了解它们的行为。活性趋势取决于金属比率，并且由于金属氧化态向更高数字的变化而不同于已知的 NiFeOOH 材料。在这里，我们表明尽管在结构上是分开的，但 Ni 和 Fe 对 OER 具有协同作用。然而，它们通过一个大型有机芳香系统以电子方式连接，该系统促进了它们之间的电子共享。在混合金属卟啉气凝胶中，发现最佳比例为 Ni：Fe = 35：65，而氧化物/羟基氧化物材料的比例为 80：20 是最理想的。