Polyaniline-integrated NiFe-MOF/V2CTx MXene ternary electrode for hybrid supercapattery energy storage and oxygen evolution electrocatalysis

초록

Hybrid supercapattery devices require electrode materials that can deliver high Faradaic capacity, rapid charge transport, stable cycling behavior, and additional electrocatalytic functionality. In this work, a NiFe-MOF/ V2CTx@PANI ternary composite was synthesized as a bifunctional electrode material for hybrid energy storage and alkaline oxygen evolution reaction (OER). The composite combines the redox-active Ni/Fe centers of NiFe-MOF, the conductive layered framework of V2CTx MXene, and the pseudocapacitive polymer network of poly-aniline (PANI). This integrated architecture improves electroactive-site accessibility, interfacial conductivity, and ion/electron transport within the electrode. In a three-electrode system, the optimized NiFe-MOF/V2CTx@PANI electrode delivered a specific capacity of 1868C g-1 at 10 mV s-1 from cyclic voltammetry and 2747C g-1 at 2 A g-1 from galvanostatic charge-discharge analysis. An asymmetric NiFe-MOF/V2CTx@PANI//AC device was further assembled using activated carbon as the negative electrode, achieving a specific capacity of 462C g-1 at 2 A g-1, an energy density of 102.7 Wh kg-1, and a power density of 1756 W kg-1. The device retained 85.4% of its initial capacity after 5000 cycles, with a Coulombic efficiency of 92.7%, indicating stable reversible charge storage. Dunn's kinetic analysis confirmed a hybrid charge-storage mechanism involving both diffusion-controlled Faradaic reactions and surface-controlled capacitive processes. In addition, the NiFe-MOF/ V2CTx@PANI composite showed promising OER activity in 1 M KOH, requiring an overpotential of 229.83 mV at 10 mA cm-2 and exhibiting a Tafel slope of 78.34 mV dec-1. These results demonstrate that NiFe-MOF/ V2CTx@PANI is a promising bifunctional electrode material for hybrid supercapattery devices and alkaline electrocatalysis.

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