The reduced phosphomolybdate as dual-functional electrocatalyst and electrochemical sensor for detecting hydrogen peroxide and dopamine

Two reduced phosphomolybdate hybids, (Hbtb)2 (btb)[CuMo12O24 (OH)6(H2PO4)6(HPO4)2]·7H2O (1) and [{Ni(tpp)}2{Ni(H2O)0·5Na2 (H2O)1.5}2{NiMo12O24(OH)6(PO4)6(H2PO4)2}]·2H2O (2), (btb ​= ​1,4-bis (1,2,4-triazol-1-yl)butane; tpp ​= ​2,4,6-tri-(2,2,3-pyridyl)-1-pyridine) were synthesized and characterized. Compound 1 is a 12-linked 3D supermolecule web with a 336∙448∙57 topology. In compound 2, an unusual ligand bpp was synthesized in situ from simple ligands ptz and dpp. Each {Ni(bpp)} modified single-arm {Ni(P4Mo6)2} dimer were joined to two hexanuclear junction unit {Na4Ni2(H2O)4} to yield an extended 1-D chain, which were extended into stacked 3-D networks with irregular apertures via unique multinuclear hybrid rings and rich π-π interaction. Compound 2 possesses more prominent electrocatalytic activity than 1, thus 2-AB-GCE was studied as a sensor. The modified electrode shows the lower detection line (0.007 ​mM and 0.032 ​μM) for both H2O2 and DA in the wider linear range, as well as merit selectivity, stability, and reproducibility. The outstanding sensing properties are correlated with the enhance redox activity, ion/electron transfer ability and structural stability due to the irregular pore structure formed by the introduction of {Ni(tpp)} complexes and π-π interactions. The accurate detection of two substrates in the human serum and urine testifies the practical detection ability of 2-AB-GCE in biological samples.