Rapid synthesis of amino acid polyoxometalate nanotubes by one-step solid-state chemical reaction at room temperature
A novel and convenient method—solid-state chemical reaction at room temperature—is reported for the synthesis of amino acid polyoxometalate nanotubes. As a convenient synthesis method for nanomaterials, it may open up a new pathway for the fabrication of organic–inorganic hybrid materials with nanotubular structure. Here, three novel tyrosine (Tyr) polyoxometalate nanotubes, (HTyr)3PMo12O40 · 3H2O, (HTyr)3PW12O40 · 3H2O, and (HTyr)4SiW12O40 · 5H2O are successfully synthesized via a one-step solid-state chemical reaction at room temperature. Elemental analysis confirms the rationality of composition for the samples. Infrared spectroscopy, X-ray diffraction, and 31P magic-angle spinning NMR results prove that the samples still possess Keggin-type structures. Scanning and transmission electron microscopies suggest that the three samples are comprised of nanotubes with remarkably uniform shape and size, with diameters from 50 to 150 nm and lengths of up to several micrometers. Cyclic voltammograms of samples in 1 mol L–1 H2SO4 indicate that three redox waves correspond to three two-electron processes resulting from the reduction/oxidation of the heteropoly anion.