Abstract The non-platinum metal-nitrogen-carbon (M-NC) system is a class of highly active oxygen reduction reaction (ORR) electrocatalysts that are well known and widely used in fuel cell applications. Herein, one simple synthesizing method of efficient M-NC electrocatalysts is proposed by the direct pyrolysis of a pretreated core-shell structure of ZnO@ZIF-8 containing metal-ammonia complex (MAC, [M(NH3)x]n+) from the polydisperse self-sacrificing MOF-5 cubes. The as-pyrolyzed M-NC (M = Co, Ag, Cu, and Ni) electrocatalysts showcase high electrocatalytic ORR activity in an alkaline medium. Among them, Co-NC catalyst exhibits an excellent ORR performance where its E1/2 = 0.80 V, JL = 5.88 mA cm−2, as well as Tafel slope of 67.0 mV dec−1 are close to commercial Pt/C and Ag-NC, better than the other two catalysts of Cu-NC and Ni-NC. Impressively, zinc-O2 batteries assembled with M-NC materials exhibit the better discharge performance, and have great potential in the practical energy conversion and storage. The experimental demonstration of metal-based nanoparticles and active M-N sites in the carbonaceous matrix can be efficiently used to promote the ORR activity, which is derived from a synergistic contribution of its particular hollow structure, large specific surface area, rich M-N active sites, and high degree of graphitization. This attractive preparation approach provides us a powerful contribution to the construction of high-performance carbon-based ORR electrocatalysts.

中文翻译：

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由金属-氨络合物浸渍的金属-有机骨架衍生的立方形金属-氮-碳，用于高效氧还原反应

摘要 非铂金属-氮-碳（M-NC）体系是一类高活性氧还原反应（ORR）电催化剂，在燃料电池应用中广为人知。在此，提出了一种简单的高效 M-NC 电催化剂合成方法，通过直接热解含有金属氨络合物（MAC，[M(NH3)x]n+）的 ZnO@ZIF-8 核壳结构，来自多分散自牺牲 MOF-5 立方体。热解后的 M-NC（M = Co、Ag、Cu 和 Ni）电催化剂在碱性介质中表现出高电催化 ORR 活性。其中，Co-NC 催化剂表现出优异的 ORR 性能，其 E1/2 = 0.80 V，JL = 5.88 mA cm-2，以及 67.0 mV dec-1 的 Tafel 斜率接近商业 Pt/C 和 Ag- NC，优于其他两种催化剂Cu-NC和Ni-NC。令人印象深刻的是，M-NC材料组装的锌氧电池具有更好的放电性能，在实际的能量转换和存储方面具有巨大的潜力。金属基纳米粒子和碳质基体中活性 MN 位点的实验证明可以有效地用于促进 ORR 活性，这是由于其特殊的中空结构、大比表面积、丰富的 MN 活性位点和高度石墨化。这种有吸引力的制备方法为我们构建高性能碳基 ORR 电催化剂做出了巨大贡献。金属基纳米粒子和碳质基体中活性 MN 位点的实验证明可以有效地用于促进 ORR 活性，这是由于其特殊的中空结构、大比表面积、丰富的 MN 活性位点和高度石墨化。这种有吸引力的制备方法为我们构建高性能碳基 ORR 电催化剂做出了巨大贡献。金属基纳米粒子和碳质基体中活性 MN 位点的实验证明可以有效地用于促进 ORR 活性，这是由于其特殊的中空结构、大比表面积、丰富的 MN 活性位点和高度石墨化。这种有吸引力的制备方法为我们构建高性能碳基 ORR 电催化剂做出了巨大贡献。