Water exchange reactivity and stability of cobalt polyoxometalates under catalytically relevant pH conditions: insight into water oxidation catalysis.
Water exchange reactivity and stability of cobalt polyoxometalates under catalytically relevant pH conditions: insight into water oxidation catalysis.
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DOI：
10.1021/ic201243n
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发表时间：
2011-08
影响因子：
4.6
通讯作者：
D. Lieb;A. Zahl;Elizabeth F. Wilson;C. Streb;Leanne C. Nye;K. Meyer;I. Ivanović‐Burmazović
中科院分区：
文献类型：
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作者：
D. Lieb;A. Zahl;Elizabeth F. Wilson;C. Streb;Leanne C. Nye;K. Meyer;I. Ivanović‐Burmazović
本文用~（17）O-NMR和超高分辨电喷雾质谱研究了纯无机分子钴基水氧化催化剂[Co（4）（II）（H（2）O）（2）（α-P（1）W（9）O（34））（2）]（10-）（1）在催化相关pH范围（pH 6-10）内的水交换。并与在相同pH范围内稳定的非活性配合物[Co（II）（H（2）O）（1）Si（1）W（11）O（39）]（6-）（2）进行了比较。所获得的结果提供了在催化相关条件下在均相金属氧化物催化剂上与水氧化相关的基元反应步骤的机理细节。结果表明，1和2的结构完整性保持，没有去质子化的水配体上的Co（II）中心发生，水交换不经历任何机械转换在催化pH条件。我们已经证明，水交换过程是由周围的水结合位点的集群环境的影响，是足够快的水氧化催化不限速。
Water exchange on a molecular, purely inorganic cobalt-based water oxidation catalyst, [Co(4)(II)(H(2)O)(2)(α-P(1)W(9)O(34))(2)](10-) (1), in the catalytically relevant pH region (pH 6-10) is studied using (17)O-NMR spectroscopy and ultrahigh-resolution electrospray ionization mass spectrometry. The results are compared with those of the inactive [Co(II)(H(2)O)(1)Si(1)W(11)O(39)](6-) (2), which is stable in the same pH region. The results obtained provide mechanistic details of the elementary reaction step related to the water oxidation on homogeneous metal oxide catalysts under catalytically relevant conditions. It is shown that the structural integrity of 1 and 2 is maintained, no deprotonation of the aqua ligands on the Co(II) centers occurs, and the water exchange does not undergo any mechanistic changeover at the catalytic pH conditions. We have demonstrated that the water exchange process is influenced by the cluster environment surrounding the water binding sites and is fast enough to not be rate-limiting for the water oxidation catalysis.