A host-guest compound formed by Cu₃[P₂W₁₈O₆₂] and HKUST-1 with capacitance and H₂O₂ sensing properties

Polyoxometalate-based metal-organic frameworks (POMOFs) have received wide attention in supercapacitors and H₂O₂ detection due to their possession of the rich redox active sites of polyoxometalates (POMs) and the ordered structure of metal-organic frameworks (MOFs). In this study, we successfully synthesized a host-guest Cu₃[P₂W₁₈O₆₂]@HKUST-1 (HRBNU-7) compound by a grinding method. Cu₃[P₂W₁₈O₆₂] successfully entered the HKUST-1 pores as confirmed by the results of infrared (IR) spectroscopy, powder X-ray diffraction (PXRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The specific capacitance of HRBNU-7 is 318.6 F g^-1 at 1 A g^-1 in a three-electrode system using nickel foam as the collector. The specific capacity retention is 92.36% after 5000 cycles. The assembled symmetrical supercapacitor (SSC) achieved a high energy density of 10.58 W h kg^-1 at a power density of 500.00 W kg^-1. In addition, HRBNU-7 exhibits excellent electrochemical detection of H₂O₂, including a wide linear range of 0.5 μM-0.3 mM, a low detection limit of 0.17 μM, and excellent selectivity and stability, and it can be effectively utilized for the analysis of H₂O₂ content in actual serum samples. These excellent properties are attributed to the unique redox activity of Cu₃[P₂W₁₈O₆₂] and the high specific surface area of HKUST-1. This work offers a strategy for exploring POMOFs as electrode materials in supercapacitors and electrochemical sensors.