Experimental and theoretical study of bifunctional electro-catalysts constructed from different Polyoxometalates and Ag-bimpy segments

Abstract

In this work, upon subtle POMs variation, we reported on the assembly and performances of three new bimetallic component organic-inorganic hybrids, [Ag2(bimpy)(VV2O6)](1), [Ag3(bimpy)2(β-MoVI8O26)](2), [Ag4(bimpy)2(H2O)2(α-SiWVI12O40)]•2H2O (3) (bimpy = 3,5-bis(1-imidazoly) pyridine). Compound 1 with 3D framework structure is featured by {-V-O-V-}n helical chains, {Ag3} clusters and {bimpy-Ag-bimpy} units. Compound 2 has a 3,3,6,6-connected 3D architecture with the (43)(43)(42•69•7•83)(46•52•64•7•82) topology. Compound 3 has a 3,3,4-connected 2D layer with (62•8)(62•8)(66) topology. The electrochemical and bifunctional electro-catalytic activities of three compounds have been conducted. The experimental results show that β–[Mo8O26]4− hybrid displays better electrocatalytic performance than [V2O6]2− and Keggin-type hybrids for reduction of nitrite, while [V2O6]2− hybrid exhibits better electrocatalytic activity than β–[Mo8O26]4- and Keggin hybrids towards oxidations of ascorbic acid. Furthermore, the molecular electrostatic potential and frontier molecular orbital were performed.