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.