Design of iron( <scp>iii</scp> ) phthalocyanine/reduced graphene oxide nanocomposites on nickel foam as hybrid supercapacitors

It is well known that the position and number of substituents affect the electrochemical properties of electrodes <i>via</i> both altering the electropolymerization process and the redox activities of electropolymerized films. This study presents the synthesis of three new iron(III) phthalocyanines (1-3) bearing four or eight 9<i>H</i>-carbazol-2-yloxy groups at the non-peripheral or peripheral positions of the phthalocyanine ring. The newly synthesized macromolecules were characterized by performing spectroscopic techniques (FT-IR, UV-Vis, and MALDI-TOF) and used for the functionalization of graphene oxide nanosheets. Then, the surface of nickel foam (NiF) electrodes was modified with the resultant nanocomposites <i>via</i> a facile one-step electrodeposition strategy. During this process, the surface of the nickel foam electrodes was fabricated with a layer formed of simultaneous polymerization of iron(III) phthalocyanines and electrochemical reduction of graphene oxide. The supercapacitive properties of the prepared electrodes were examined and then compared with those of unmodified nickel foam, lone iron(III) phthalocyanine, and phthalocyanine/graphene oxide electrodes to study the synergistic effect of the electrode-forming species. All the hybrid electrodes showed higher supercapacitive performances. Among all the hybrid electrodes, the NiF/rGO₂-1 electrode exhibited a higher specific capacitance of 590.4 F g^-1 at 0.5 A g^-1 compared to NiF/1 (270.2 F g^-1). Furthermore, NiF/rGO₂-1 displayed superior cycling stability, retaining 85.2% of its specific capacitance after 5000 continuous charge-discharge cycles, whereas NiF/1 retained only 71.4%, highlighting the valuable effect of rGO decoration. Consequently, these metallophthalocyanine-reduced graphene oxide composites serve as promising agents for designing next-generation energy storage devices.