Fractal supported electrochemical analysis of MoO3 decorated AlOOH binary composite for supercapacitor application

Abstract

The AlOOH/MoO₃ binary composite electrodes are synthesized by layer-by-layer method to enhance the supercapacitive property of AlOOH by taking advantage of multiple oxidation states of molybdenum. The X-ray diffraction characterization reveals the polycrystalline nature of nanocomposite. The elements and their chemical states are analysed using X-ray photoelectron spectroscopy. The binary composite exhibits interconnected network-like morphology resembling a fractal nature. The three-electrode measurement in 1 M KOH electrolyte shows the highest specific capacity (C_s) of 1638.15 C g^-1@ 5 mV s^-1 for binary composite, which is greater than the capacity of individual components. Also, we get C_s of 1124.41 C g^-1 for 10 cycle MoO₃ while its theoretical capacity is 1005 C g^-1. The excellent electrochemical performance is a consequence of multiple redox active sites present in the nanocomposite, lower resistance, porous interconnected network-like structure, and shorter relaxation time. The synergy of AlOOH with MoO₃ enhances its charge storage capacity. The obtained electrochemical results are also theoretically supported by fractal analysis. Among all the electrodes, the 10 cycle AlOOH/MoO₃ nanocomposite displays high value of fractal dimension, which is advantageous for supercapacitor application. Furthermore, we have fabricated a symmetric supercapacitor device to understand the practicality of current work. The fabricated device displays C_s of 68.41 F g^-1 within 1.6 V potential window with ∼71 % capacity retention and 100 % coulombic efficiency after 7000 charge-discharge cycles. The highest energy density of 24.32 Wh kg^-1 is achieved for the power density of 3907 W kg^-1.