This work confirms a trade‐off relationship between the high redox potential of Cu and the oxygen‐binding ability of Cu‐based oxygen reduction reaction (ORR) electrocatalysts. As the ORR is mediated by Cu(I) species, a positive shift of the Cu(II/I) potential is required to increase the ORR onset potential. However, the ready simultaneous autoreduction of Cu(II) to Cu(I) in Cu complexes, owing to high redox potentials, results in the formation of a closed tetrahedral configuration that is inactive for O₂ adsorption and, therefore, for the ORR. To mitigate this problem, we synthesized a Cu‐modified S‐linked covalent triazine framework (Cu−S‐CTF) as an electrocatalyst for the ORR in neutral solutions. The Cu(I) ions in this material have a distorted three‐coordinated structure with accessible coordination sites for O₂, because the inflexibility of the CTF suppresses the formation of the tetrahedral configuration. The ORR onset potential of Cu−S‐CTF was 880 mV versus a reversible hydrogen electrode at pH 7. This is the first example of an ORR electrocatalyst containing Cu sites with both high redox potential and oxygen‐binding ability.

中文翻译：

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配位不饱和铜（I）掺杂的硫连接共价三嗪骨架作为还原氧的电催化剂

这项工作证实了铜的高氧化还原电势与铜基氧还原反应（ORR）电催化剂的氧结合能力之间的折衷关系。由于ORR是由Cu（I）物种介导的，因此需要Cu（II / I）电势的正向移动来增加ORR起始电势。但是，由于高的氧化还原电位，Cu络合物中的Cu（II）易于同时自动还原为Cu（I），导致形成对O ₂无效的封闭的四面体构型吸附，因此用于ORR。为缓解此问题，我们合成了Cu修饰的S-连接的共价三嗪骨架（Cu-S-CTF）作为中性溶液中ORR的电催化剂。这种材料中的Cu（I）离子具有扭曲的三配位结构，并且具有可接近的O ₂配位位点，因为CTF的不弹性会抑制四面体构型的形成。在pH 7时，Cu-S-CTF的ORR起始电势为可逆氢电极，为880 mV。这是ORR电催化剂的第一个示例，其中包含具有高氧化还原电势和氧结合能力的Cu位。