Graphene oxide synthesis at a nonthermal plasma-water interface.

We report a scalable and sustainable method for synthesizing graphene oxide (GO) via a non-thermal atmospheric nano-second pulsed plasma (NSPP) process, using methane as the carbon source and water as the substrate. Unlike conventional chemical vapor deposition (CVD), which demands high temperatures, low pressures, and inert gases, this approach operates at ambient conditions without additional gas inputs. The plasma decomposes methane directly on or near the water surface, producing high-purity, single-layer GO with tunable oxygen content and flake size. Gas chromatography confirms substantial hydrogen generation and minimal greenhouse gas emissions. Atomic Force Microscopy (AFM) analysis verifies single-layer morphology. Scaling the process with a four-gap reactor yields 5 g of GO per day, exceeding conventional CVD output while reducing cost and environmental impact. This plasma-driven strategy provides an energy-efficient route for large-scale GO production, with potential applications in electronics, energy storage, coatings, and concrete composites.