Key Laboratory of Marine Chemistry Theory and Technology, Ministry of Education, College of Chemistry and Chemical Engineering, Ocean University of China, Qingdao, 26610, Shandong, China.
Shandong Provincial Key Laboratory of Biochemical Engineering, College of Marine Science and Biological Engineering, Qingdao University of Science and Technology, Qingdao, 266042, Shandong, China.
J Biol Inorg Chem. 2021 May;26(2-3):205-216. doi: 10.1007/s00775-020-01846-4. Epub 2021 Feb 5.
Two biologically inspired tetranuclear nickel complexes [Ni(L-H)(CHCOO)]·Cl (1) and [Ni(L-H)(CHCOO)]·2CHOH (2) (L = di(pyridin-2-yl)methanediol) have been synthesized and investigated by a combination of X-ray crystallography, PXRD, electrochemistry, in-situ UV-Vis spectroelectrochemistry and DLS. Both of the two complexes feature a core composed of four Ni(II) ions with the same peripheral ligation provided by the anionic di(pyridin-2-yl)methanediol and MeCOO ligands. Whereas, complex 1 possesses one distorted cubane-like [Ni(µ-O)] core, while 2 has one extended butterfly-like [Ni(µ-O)] core. The homogeneous electrocatalytic reactivity of the two water-soluble complexes for water oxidation have been thoroughly studied, which demonstrates that both of them can efficiently electrocatalyze water oxidation with high stability under alkaline conditions, at relatively low over-potentials (η) of 420-790 mV for 1 and 390-780 mV for 2, both in the pH range of 7.67-12.32, with the high TOF of about 139 s (1) and 69 s (2) at pH = 12.32, respectively. By a series of comparative experiments for complexes 1 and 2, we proposed that their crystal geometries play an important role in their electrocatalytic reactivity for water oxidation. We verified that biomimetic cubane geometry could promote OER catalysis with two very similar compounds for the first time. Compared with 2, the biomimetic cubane topology of 1 could promote OER catalysis by facilitating efficient charge delocalization and electron-transfer.
两种受生物启发的四核镍配合物[Ni(L-H)(CHCOO)]·Cl（1）和[Ni(L-H)(CHCOO)]·2CHOH（2）（L=二（吡啶-2-基）甲醇）已通过 X 射线晶体学、PXRD、电化学、原位 UV-Vis 光谱电化学和 DLS 的组合进行了研究。这两种配合物都具有由阴离子二（吡啶-2-基）甲醇和 MeCOO 配体提供的相同外围配体的四核 Ni(II)离子核心。然而，配合物 1 具有一个扭曲的立方烷状[Ni(µ-O)]核心，而 2 具有一个扩展的蝴蝶状[Ni(µ-O)]核心。两种水溶性配合物对水氧化的均相电催化反应性进行了彻底研究，结果表明，在碱性条件下，它们都可以在相对较低的过电位（η）下高效电催化水氧化，1 的η为 420-790 mV，2 的η为 390-780 mV，pH 值范围为 7.67-12.32，在 pH = 12.32 时，TOF 分别高达约 139 s（1）和 69 s（2）。通过对配合物 1 和 2 的一系列对比实验，我们提出它们的晶体几何形状在水氧化的电催化反应性中起着重要作用。我们首次验证了仿生立方烷几何形状可以通过促进有效电荷离域和电子转移来促进 OER 催化作用。与 2 相比，1 的仿生立方烷拓扑结构可以通过促进有效的电荷离域和电子转移来促进 OER 催化作用。
