Thin films based on nanocomposites of crumpled graphene fully decorated with Prussian blue: a new material for aqueous battery systems

This study involves synthesizing thin films through an interfacial method, which relies on composites of Prussian blue nanoparticles and nanostructures derived from graphene, known as crumpled graphene. The resulting compounds were subjected to evaluation for potential applications in aqueous battery-type energy storage systems. Considering the importance of structure-property relationships and applications, the carbon nanostructures were previously processed to assess their morphological characteristics and electrochemical performance for the growth of Prussian blue nanocubes. To this end, the spray-pyrolysis method was employed, resulting in crumpled graphene infused with β-FeOOH and Fe₂O₃ (β-iron(III) oxyhydroxide and iron (III) oxide) species. Composites of crumpled graphene and Prussian blue were synthesized through the electrodeposition method via cyclic voltammetry, which formed Prussian blue nanocubes on the surface of crumpled graphene with sizes ranging from 48 to 153 nm depending on the number of cycles. Specific capacity values varied based on the compound structure, with the highest recorded value of 50.4 mA h g^-1 at a rate of 500 mA g^-1 for the PB_10 composite achieved in an aqueous electrolyte of 0.1 mol L^-1 KCl vs. Ag|AgCl (3.0 mol L^-1 KCl). The PB_10 electrode was further studied using different electrochemical techniques and employed in a coin cell battery system, demonstrating a discharge capacity of 25.0 mA h g^-1 at 250 mA g^-1. Additionally, the device retained 97% of its capacity after cycling at various current densities, highlighting its stability.