Laser-Assisted Explosive Synthesis and In Situ Transfer of Graphene/MnO Nanohybrids with Tunable MnO Content for...

Laser irradiation provides a low-cost, environmentally friendly route for the growth of graphene-based materials with high spatial resolution. In this study, we demonstrate a laser-assisted "dry" electrode fabrication strategy based on the simultaneous synthesis and in situ transfer of graphene/MnO nanohybrids, obtained through the decomposition of polyimide that is coated with a variable metal salt loading. Increasing metal salt loading results in enrichment of porous graphene films with MnO nanoparticles and a concomitant increase in particle size. At the highest MnO loading, the areal capacitance reaches 307.6 mF cm^-2 at 0.2 mA cm^-2─approximately 200 times higher than that of pristine graphene─corresponding to a specific capacitance of ∼293 F g^-1, while a low MnO loading yields a maximum specific capacitance of ∼401 F g^-1. After 10,000 cycles at 10 mA cm^-2, the electrodes retain ∼63% of their initial capacitance, with post-mortem analysis suggesting the dissolution of Mn²⁺ and subsequent electrooxidation of a fraction of Mn²⁺ species in the form of layered δ-MnO₂. This work demonstrates a scalable and tunable approach for decorating laser-assisted graphene with electrochemically active metal oxides, enabling the extension of this method to various metal precursors.