Electrochemical Properties of Polyoxometalates as Electrocatalysts.

Polyoxometalates: Very large clusters - Nanoscale magnets

Two novel polyoxometalate (POM)-based metal–organic frameworks (MOFs), [TBA]3[e-PMoV8MoVI4O36(OH)4Zn4][BTB]4/3·xGuest (NENU-500, BTB = benzene tribenzoate, TBA+ = tetrabutylammonium ion) and [TBA]3[e-PMoV8MoVI4O37(OH)3Zn4][BPT] (NENU-501, BPT = [1,1′-biphenyl]-3,4′,5-tricarboxylate), were isolated. In these compounds, the POM fragments serving as nodes were directly connected with organic ligands giving rise to three-dimensional (3D) open frameworks. The two anionic frameworks were balanced by TBA+ ions residing inside the open channels. They exhibit not only good stability in air but also tolerance to acidic and basic media. Furthermore, they were employed as electrocatalysts for the hydrogen evolution reaction (HER) owing to the combination of the redox activity of a POM unit and the porosity of a MOF. Meanwhile, the HER activities of e(trim)4/3, NENU-5, and HKUST-1 were also studied for comparison. Remarkably, as a 3D hydrogen-evolving cathode operating in acidic electrolytes, NENU-500 exhibits the hig...

Ultrastable Polymolybdate-Based Metal–Organic Frameworks as Highly Active Electrocatalysts for Hydrogen Generation from Water

Self-assembly of nanometer-scale [Cu24I10L12]14+ cages and ball-shaped Keggin clusters into a (4,12)-connected 3D framework with photoluminescent and electrochemical properties.

Two polyoxometalate-templated organic–inorganic hybrid porous frameworks, namely, [Cu2(H2O)2(bpp)2Cl][PM12O40]·∼20H2O (for 1, M = W; for 2, M = Mo; bpp = 1,3-bis(4-pyridyl)propane), were self-assembly obtained and structurally determined by elemental analyses, inductively coupled plasma analyses, infrared spectroscopy, and single-crystal X-ray diffraction analyses. Single-crystal X-ray analysis of these crystals revealed that both of the structures are constructed from eight-connected three-dimensional coordination polymer hosts [Cu2(H2O)2(bpp)2Cl]n3n+ and ball-shaped Keggin-type guests [PM12O40]n3n− as templates. The polymer hosts resulted from a bcc-type framework with nanotubes, and the nanotubes can be regarded as a tetra-stranded helix structure. Furthermore, compounds 1 and 2 exhibit photoluminescent properties at ambient temperature, and the compound 2 bulk-modified carbon paste electrode (2-CPE) displays good electrocatalytic activity toward the reduction of nitrite.

Self-assembly of organic-inorganic hybrid materials constructed from eight-connected coordination polymer hosts with nanotube channels and polyoxometalate guests as templates.

Xiaodan Xi

Papers

Study of the electrocatalytic reduction of nitrite with silicotungstic heteropolyanion

Electrochemical behavior of the molybdotungstate heteropoly complex with neodymium, K10H3[Nd(SiMo7W4O39)2] · xH2O in aqueous solution

Rapid identification of the short-lived intermediates in alternating-current electrolysis by mass spectrometry.