{P₂W₁₈O₆₂}-Encapsulated Potassium-Ion Nanotubes Intercalated in Copper Biimidazole Frameworks for Supercapacitors and Hydrogen Peroxide Sensing

We synthesized {P2W18O62}-encapsulated potassium-ion nanotubes intercalated in copper biimidazole frameworks [{K(H2O)}2{Cu2(bim)2}2(P2W18O62)] (1; bim = biimidazole) with a {32.4.6.72}4{3}4{43}2{46.68.83.1024.164} topology structure by a hydrothermal method. K+ ion can encapsulate {P2W18O62} through strong covalent bonding, which is beneficial to the uniform dispersion of {P2W18O62}; furthermore, the insertion of copper biimidazole frameworks can introduce N-atom donors and apertures to reduce the resistance of the materials. Compound 1 as an electrode material has a high specific capacity (1070 F g–1 at 2 A g–1) in a wide potential range of −0.5–0.7 V and exhibits the excellent rate ability (81.8%) and a long cycling stability (89.8% retention after 5000 cycles). A fully symmetrical water system supercapacitor is prepared with an energy density of 0.71 W h kg–1 at a power density of 116.17 W kg–1. Meanwhile, compound 1 is tested as a new sensitive current hydrogen peroxide sensor and displays a linear range of 1.2–11.7 mM and a high sensitivity of 0.094 μA mm–1 cm2 with a minimum detection limit of 72.1 mM. The photocatalytic decomposition rates are 97.20% for MB, 96.30% for RhB, and 86.53% for MO after 120, 150, and 240 min, respectively. These advantages indicate that the architecture of compound 1 has great potential in photoelectrochemical applications.