Cui Ying, Shi Lei, Yang Yanyi, You Wansheng, Zhang Lancui, Zhu Zaiming, Liu Meiying, Sun Licheng
Institute of Chemistry for Functionalized Materials, Liaoning Normal University, Dalian, 116029, P. R. China.
Dalton Trans. 2014 Dec 14;43(46):17406-15. doi: 10.1039/c4dt01538j.
A 1D chain-like Ag(I)-substituted Keggin polyoxotungstophosphate, K3[H3Ag(I)PW11O39]·12H2O, has been synthesized in a high yield and characterized by single-crystal X-ray diffraction, XRD, IR, TG/DTA and elemental analysis. When the polyoxotungstophosphate is dissolved in aqueous solutions, (31)P NMR, MS and conductivity analyses indicate that a Ag(I) anion-complex formulated as H3Ag(I)(H2O)PW11O39 is formed and is stable in a solution of pH 3.5-7.0. The oxidation of H3Ag(I)(H2O)PW11O39 by S2O8(2-) has been studied by ESR, UV-Visible spectroscopy, (31)P NMR and UV-Raman spectroscopy. It was found that H3Ag(I)(H2O)PW11O39 can be oxidized to dominantly generate a dark green Ag(II) anion-complex H3Ag(II)(H2O)PW11O39 and a small amount of Ag(III) complex H3Ag(III)OPW11O39, simultaneously evolving O2. Compared with [Ag(I)(2,2'-bpy)NO3] and AgNO3, H3Ag(I)(H2O)PW11O39 has the higher activity in chemical water oxidation. This illustrates that the PW11O39 ligand plays important roles in both the transmission of electrons and protons, and in the improvement of the redox performance of silver ions. The rate of O2 evolution is a first-order law with respect to the concentrations of H3Ag(I)(H2O)PW11O39 and S2O8(2-), respectively. A possible catalytic water oxidation mechanism of H3Ag(I)(H2O)PW11O39 is proposed, in which the H3Ag(II)(H2O)PW11O39 and H3Ag(III)OPW11O39 intermediates are determined and the rate-determining step is H3Ag(III)OPW11O39 oxidizing water into H2O2.
一种一维链状银（I）取代的Keggin型聚氧钨磷酸盐K3[H3Ag（I）PW11O39]·12H2O已被高产率合成，并通过单晶X射线衍射、XRD、红外光谱、TG/DTA和元素分析进行了表征。当聚氧钨磷酸盐溶解在水溶液中时，31P NMR、质谱和电导率分析表明，形成了一种化学式为[H3Ag（I）（H2O）PW11O39]（3-）的银（I）阴离子络合物，且在pH为3.5 - 7.0的溶液中稳定。通过电子自旋共振（ESR）、紫外可见光谱、31P NMR和紫外拉曼光谱研究了[H3Ag（I）（H2O）PW11O39]（3-）被S2O8（2-）氧化的过程。发现[H3Ag（I）（H2O）PW11O39]（3-）可被氧化，主要生成深绿色的银（II）阴离子络合物[H3Ag（II）（H2O）PW11O39]（2-）和少量的银（III）络合物[H3Ag（III）OPW11O39]（3-），同时释放出O2。与[Ag（I）（2,2'-联吡啶）NO3]和AgNO3相比，[H3Ag（I）（H2O）PW11O39]（3-）在化学水氧化中具有更高的活性。这表明[PW11O39]（7-）配体在电子和质子传递以及提高银离子的氧化还原性能方面都起着重要作用。O2的释放速率分别与[H3Ag（I）（H2O）PW11O39]（3-）和S2O8（2-）的浓度呈一级关系。提出了[H3Ag（I）（H2O）PW11O39]（3-）可能的催化水氧化机理，其中确定了[H3Ag（II）（H2O）PW11O39]（2-）和[H3Ag（III）OPW11O39]（3-）中间体，且速率决定步骤为[H3Ag（III）OPW11O39]（3-）将水氧化为H2O2。
