Polyoxometalate Integrated with Conducting Polymer Nanocomposites for Supercapacitor and Biological Sensor Applications

Nanostructured redox-active composite electrode materials have been developed for energy storage applications to address conventional carbon-based supercapacitor's limited electrochemical performance. Polyoxometalates (POMs) and conducting polymers (CP) have significantly enhanced the pseudocapacitive activity of these electrode materials. In this study, we synthesized H₄[PVW₁₁O₄₀]·<i>x</i>H₂O (PVW₁₁) and combined it with polypyrrole (PPy) and polyaniline (PAni) separately to improve energy performance and conduct electrochemical analysis. The PVW₁₁-PPy outperformed the PVW₁₁-PAni composite, achieving an energy density of 49.07 W h kg^-1 and a specific capacitance of 405.16 F g^-1. The supercapacitor cells showed a cyclic retention of 85.13% and 99.99% Coulombic efficiency after 6000 galvanostatic charge-discharge (GCD) cycles. The PVW₁₁-PPy composite was fabricated into a supercapacitor device that powered a set of 10 LED bulbs for 2 min using an active mass of 76 mg. Additionally, the PVW₁₁-PPy composite material was employed to sense glucose solutions with concentrations ranging from 0.04 to 0.4 mM, providing a sensitivity of 0.325 mA mM^-1 cm^-2, with limits of detection (LOD) and quantification (LOQ) of 0.381 mM and 1.270 mM, respectively.