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

Abstract

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(HPMo^VI₈V^IV₄O₄₀(V^IVO)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.