Antiferromagnetic Inverse Spinel Oxide LiCoVO4 with Spin-Polarized Channels for Water Oxidation
Antiferromagnetic Inverse Spinel Oxide LiCoVO4 with Spin-Polarized Channels for Water Oxidation
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DOI：
10.1002/adma.201907976
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发表时间：
2020-01-31
影响因子：
29.4
通讯作者：
Xu, Zhichuan J.
中科院分区：
文献类型：
--
作者：
Chen, Riccardo Ruixi;Sun, Yuanmiao;Xu, Zhichuan J.
开发高效的析氧反应（OER）催化剂对水电解至关重要。具有合理活性的具有成本效益的过渡金属氧化物正引起人们的关注。最近，OER反应物和产物的不同自旋构型被认为是导致缓慢反应动力学的原因。具有磁极化通道的催化剂可以选择性地去除具有相反磁矩的电子，并在OER期间保持整体自旋，从而增强三重态氧分子的演化。在此，发现反铁磁反尖晶石氧化物LiCoVO 4含有d（7）Co 2+离子，其可以在活性八面体位置下稳定，具有高自旋态S = 3/2（t（2g）（5）e（g）（2））。在高自旋构型下，每个Co 2+离子具有3 μ（B）的理想磁矩，使得尖晶石中的共边Co 2+八面体被磁极化。密度泛函理论模拟结果表明，所研究的层状反铁磁LiCoVO 4中存在磁极化通道。自旋传导沟道中每个过渡金属原子的平均磁矩（mu（ave））约为2.66 mu（B）。这样的通道能够增强在OER期间从反应物中选择性地去除自旋取向的电子，这促进了用于三重态氧分子演化的适当磁矩的积累。此外，报道的LiCoVO 4已被鉴定为具有优异OER活性的氧化物催化剂。
Exploring highly efficient catalysts for the oxygen evolution reaction (OER) is essential for water electrolysis. Cost-effective transition-metal oxides with reasonable activity are raising attention. Recently, OER reactants' and products' differing spin configurations have been thought to cause slow reaction kinetics. Catalysts with magnetically polarized channels could selectively remove electrons with opposite magnetic moment and conserve overall spin during OER, enhancing triplet state oxygen molecule evolution. Herein, antiferromagnetic inverse spinel oxide LiCoVO4 is found to contain d(7) Co2+ ions that can be stabilized under active octahedral sites, possessing high spin states S = 3/2 (t(2g)(5)e(g)(2)). With high spin configuration, each Co2+ ion has an ideal magnetic moment of 3 mu(B), allowing the edge-shared Co2+ octahedra in spinel to be magnetically polarized. Density functional theory simulation results show that the layered antiferromagnetic LiCoVO4 studied contains magnetically polarized channels. The average magnetic moment (mu(ave)) per transition-metal atom in the spin conduction channel is around 2.66 mu(B). Such channels are able to enhance the selective removal of spin-oriented electrons from the reactants during the OER, which facilitates the accumulation of appropriate magnetic moments for triplet oxygen molecule evolution. In addition, the LiCoVO4 reported has been identified as an oxide catalyst with excellent OER activity.