Four polyoxomolybdated-based 3D compounds as supercapacitors and amperometric sensors

Four polyoxomolybdated compounds based on Tetp (Tetp = 4-[4-(2-Thiophen-2-yl-ethyl)-4H-[1, 2, 4]triazole-3-yl]-pyridine), namely [Zn(Tetp)₂(H₂O)₂][(β-Mo₈O₂₆)_0.5] (Zn-Mo₈), [Co(Tetp)₂(H₂O)₂][(β-Mo₈O₂₆)_0.5] (Co-Mo₈), [Cu₄(Tetp)₆(H₂O)₂]{H₃[K(H₂O)₃](θ-Mo₈O₂₆)(Mo₁₂O₄₀)}·8H₂O (Cu-Mo₂₀) and [Cu₃(Tetp)₃][PMo₁₂O₄₀]·H₂O (Cu-PMo₁₂) are synthesized by hydrothermal methods and are used as electrode materials for supercapacitors(SCs) and electrochemical sensors. Inserting polyoxometalates (POMs) with redox active sites into transition metal compounds (TMCs) can improve the internal ion/electron transfer rate, thus effectively enhancing the electrochemical performance. Compared with the parent POMs, four compounds exhibit excellent electrochemical properties. In particular, Cu-PMo₁₂ shows an excellent specific capacitance (812.3 F g⁻¹ at 1 A g⁻¹) and stability (94.42%), as well as a wide detection range (0.05 to 1250 µM) and a low detection limit (0.057 µM) for NO₂^- sensing.