Potentiostatic synthesis of polyaniline zinc and iron oxide composites for energy storage applications

This study introduces an efficient potentiostatic method to enhance the energy storage performance of polyaniline (PN) by synthesizing PN@ZnO (PNZ), PN@Fe₂O₃ (PNF), and PN@ZnFe₂O₄ (PNZF) hybrid electrodes with defined porous morphology. The precise selection and control of the working potential during electro-polymerization and metal oxide integration using the linear sweep voltammetry was key for synthesizing the polymer hybrid electrodes reproducible and with defined composition and structure. The PNZF electrode demonstrated the highest specific capacitances of 816 F g⁻¹ and 791.3 F g⁻¹ at a scan rate of 5 mV s⁻¹ and 1.0 A g⁻¹ current density, along with high power density and energy density of 1058.4 W kg⁻¹ and 136.4 Wh kg⁻¹, and with excellent stability retaining 90 % over 4000 cycles. We could attribute the excellent performance to a low charge transfer resistance of 25.0 Ω, a predominantly surface-controlled charge storage mechanism, and a porous morphology with uniform distribution of ZnFe₂O₄ particles in the polymer network, all resulting from the electrochemical synthesis method. Our study provides valuable and new insights into the structural, optical, and electrochemical properties of PN composites, particularly PNZF.