g-CN not only has high content of pyridine nitrogen, but also has a special two-dimensional porous structure, which is an ideal diatomic catalytic host materials. In this work, homonuclear and heteronuclear dual-atom catalysts (DACs, TM-TM@g-CN, TM = Mn, Fe, Co, Ni) were constructed using single-layer g-CN as the carrier material of DACs, and their potential as sulfur-hosting materials and electrocatalytic materials for lithium-sulfur batteries was explored through first principles comprehensively. The results show that the coupling between the two metal atoms in heteronuclear DACs can regulate the spin state of each other's d-electrons, so that the anchoring and catalytic effects of heteronuclear DACs on polysulfide are more excellent than that of homonuclear DACs. Co-Mn@g-CN, when utilized as the cathode material in lithium-sulfur batteries, offers exceptional properties due to the hybridization between Mn high-spin state d electron and Co half-filled d orbital. This unique interaction not only enables the polysulfide to exhibit the lowest Gibbs free energy during conversion, but also results in the lowest reaction energy barrier of 0.26 eV for the conversion of LiS to LiS. Furthermore, it is found that when 3d transition metal atoms act as heteronuclear DACs, the coupling between metal ions with high-spin states at the active site and metal ions with empty orbitals or half-full d-electrons has the most significant catalytic effect on polysulfides.

中文翻译：

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嵌入单层 g-C3N3 的异核过渡金属二聚体作为锂硫电池有前景的锚定和电催化材料：第一原理计算

g-CN不仅具有较高的吡啶氮含量，而且具有特殊的二维多孔结构，是理想的双原子催化主体材料。本工作以单层 g-CN 作为 DAC 的载体材料构建了同核和异核双原子催化剂（DAC，TM-TM@g-CN，TM = Mn，Fe，Co，Ni），并研究了它们的性能。通过第一原理全面探索了锂硫电池作为硫主体材料和电催化材料的潜力。结果表明，异核DAC中两个金属原子之间的耦合可以调节彼此d电子的自旋态，使得异核DAC对多硫化物的锚定和催化效果比同核DAC更加优异。 Co-Mn@g-CN用作锂硫电池的正极材料时，由于Mn高自旋态d电子与Co半填充d轨道之间的杂化而具有优异的性能。这种独特的相互作用不仅使多硫化物在转化过程中表现出最低的吉布斯自由能，而且使LiS转化为LiS的反应能垒最低为0.26 eV。此外，研究发现，当3d过渡金属原子充当异核DAC时，活性位点具有高自旋态的金属离子与空轨道或半满d电子的金属离子之间的耦合对催化效果最显着。多硫化物。