Experimental and Theoretical Study of Two 3D Difunctional Electrocatalytic Hybrid Vanadate-Containing Metal–Organic Motifs

Two novel 3D inorganic-organic hybrids based on [V6O18]6-/[V3O9]3- clusters, [Cu18(bbpy)18(V6O18)6]·3H2O (1) and [Cu4Ag4(pty)4(V3O9)4]·H2O (2) (bbpy = 3,5-bis(1-benzimidazole) pyridine, pty = 4'-(4″-pyridyl)-2,2':6',2″-terpyridine), were isolated in the same POV/Cu/N-heterocycle ligand reaction systems. Hybrids 1 and 2 possess novel three-dimensional bimetallic frameworks derived from [V6O18]6-/[V3O9]3- clusters and Cu-organic complexes. In 1, bbpy ligands are grafted by Cu2+ to a grid ribbon 2D sheet, which are connected with benzene-like [V6O18]6- to yield a 3D framework. In 2, helical {O-V-O-V-}n chains are bridged by Cu(II) ions into a 2D layer including eight-membered rings {V6Cu2} and six-membered rings {V4Cu2}, and the adjoining sheets are joined by Ag-N coordination bonds to form a framework structure. Moreover, hybrid 1 has superior electrocatalytic properties for nitrite reduction and oxidation of ascorbic acid with electrocatalytic efficiencies of 397.2 and 96%, respectively. Hybrid 2 displays coordinated electrocatalytic performance toward oxidation reaction through V and Cu centers. Meanwhile, the corresponding theoretical studies were conducted to evaluate electrocatalytic active sites and charge distribution.