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Indexed by:期刊论文

Date of Publication:2014-01-01

Journal:DALTON TRANSACTIONS

Included Journals:SCIE、Scopus

Volume:43

Issue:46

Page Number:17406-17415

ISSN No.:1477-9226

Abstract:A 1D chain-like Ag(I)-substituted Keggin polyoxotungstophosphate, K-3[(H3AgPW11O39)-P-I]center dot 12H(2)O, 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, P-31 NMR, MS and conductivity analyses indicate that a Ag(I) anion-complex formulated as [H3AgI(H2O)PW11O39](3-) is formed and is stable in a solution of pH 3.5-7.0. The oxidation of [H3AgI(H2O)PW11O39](3-) by S2O82- has been studied by ESR, UV-Visible spectroscopy, P-31 NMR and UV-Raman spectroscopy. It was found that [H3AgI(H2O)PW11O39](3-) can be oxidized to dominantly generate a dark green Ag(II) anion-complex [H3AgII(H2O)PW11O39](2-) and a small amount of Ag(III) complex [(H3AgOPW11O39)-O-III](3-), simultaneously evolving O-2. Compared with [AgI(2,2'-bpy)NO3] and AgNO3, [H3AgI(H2O)PW11O39](3-) has the higher activity in chemical water oxidation. This illustrates that the [PW11O39](7-) 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 O-2 evolution is a first-order law with respect to the concentrations of [H3AgI(H2O)PW11O39](3-) and S2O82-, respectively. A possible catalytic water oxidation mechanism of [H3AgI(H2O)PW11O39](3-) is proposed, in which the [H3AgII(H2O)PW11O39](2-) and [(H3AgOPW11O39)-O-III](3-) intermediates are determined and the rate-determining step is [(H3AgOPW11O39)-O-III](3-) oxidizing water into H2O2.