Three polyoxometalates-based organic-inorganic hybrids decorated with Cu-terpyridine complexes exhibiting dual functional electro-catalytic behaviors.

By adjusting polyoxometalates in the same POM/Cu/terpyridine reaction systems, three new organic-inorganic hybrid solid materials based on Cu-terpyridine complexes, [Cu3(tpy)3(H2O)2(HPMoVI8VIV4O40(VIVO)2)]·2H2O (1), Cu5(tpy)5(H2O)2(α-PW12O40)2 (2), and [Cu3(tpy)3(H2O)4(α-P2W18O62)]·4H2O (3) (tpy = 2,2':6',2''-terpyridine), were prepared by using one-pot methods. X-ray structural analyses show that compounds 1-3 with a 1D chain structure constructed from Cu/tpy complexes were modified using bi-capped Keggin, Keggin and Wells-Dawson POMs. Compounds 1-3 have been fabricated to a bulk-modified carbon paste electrode to explore the electrochemical properties. Cyclic voltammetry demonstrates discrepant dual functional electro-catalytic activities toward the reduction of nitrite and the oxidation of ascorbic acid because of variant POMs. The results show that the PW12-Keggin-type hybrid exhibits a better dual functional electro-catalytic performance than bi-capped Keggin and Wells-Dawson hybrids for the reduction of nitrite and the oxidation of ascorbic acid.