Fabrication and Electrochemical Performance of Polyoxometalate-Based Three-Dimensional Metal Organic Frameworks Containing Carbene Nanocages.

Two new polyoxometalate (POM)-based three-dimensional metal organic carbene frameworks, [Ag10(trz)4(H2O)2][HPW12O40] (POMs@MCNCs-1) and [Ag10(trz)4(H2O)6][H2SiW12O40] (POMs@MCNCs-2), were hydrothermally synthesized, in which Keggin-type polyoxoanions as templates induce the formation of two different kinds of metal-carbene nanocages (MCNCs) for the first time. Combination of the reversible multielectron redox behavior and electron storage functions of POMs with the good electrical conductivity of the single-walled carbon nanotubes (SWNTs) renders the POMs@MCNCs-1/SWNT composite excellent electrochemical performance and good stability as anode materials of lithium-ion batteries, with up to 2000 mA h g-1 for the first discharge capacity and ca. 859 mA h g-1 for the second cycle at a current density of 100 mA g-1. The successful fabrication of unprecedented MCNCs into the POM-based three-dimensional metal-organic frameworks in the present work must initiate extensive research interests in diverse fields.