Graphene oxide (GO) and reduced Graphene oxide (rGO) are extensively researched for their use in water filtration membranes. However, the lack of scalable, economically viable manufacturing methods hinders their widespread application. Particularly due to incompatibility with roll-to-roll production. Herein, we present a simple and scalable method for preparation of composite GO/PVA/PEG freestanding paper via spraying deposition (FIG 1d), followed by fast (<2 s) reduction [1] using Diffuse Coplanar Surface Barrier Discharge (DCSBD) [2] (FIG 1a-b, FIG 1f).

This approach does not require any toxic chemicals, operates at atmospheric pressure and room temperature, and requires only electric power and technical nitrogen as working gas, making the process simple and compatible with in-line production. During the reduction, a quick release of gaseous products such as CO₂, CO and water vapor exfoliates the composite paper leading to an expanded, highly porous (>400 m²/g) rGO/PVA/PEG structure (FIG.1e). Such rGO/PVA/PEG composite paper can further be functionalized with a modified DCSBD set-up called DCSBD linear jet [3] (FIG.1c). Instead of standard treatment, this set-up generates...