Transient Cellulose Stabilization Enables Tap-Water Production of Graphene Nanosheet Inks from Electronic Waste

Abstract

Liquid-phase exfoliation (LPE) of graphene typically relies on purified graphite, engineered stabilizers and controlled solvent systems. Here, we report a low-infrastructure waste-to-ink route that combines electronics-derived graphite thermal-management materials with discarded newspaper-derived cellulose in untreated tap water. A commercial graphite thermal-interface sheet was used as a reproducible model feedstock, while graphite recovered from a discarded smartphone provided device-level validation. The newspaper-derived cellulose phase suppressed rapid aggregation during and after shear exfoliation, enabling metastable graphene dispersions without organic solvents, purified water or conventional molecular surfactants. Raman spectroscopy, electron microscopy, and statistical atomic force microscopy confirmed few-layer graphene nanosheets, with extended blending increasing exfoliation while reducing nanosheet thickness and lateral dimensions. For the 120 min model-feedstock dispersion, nanosheets had mean lateral dimensions of 103.27 ± 2.85 nm by 74.84 ± 1.61 nm, an apparent thickness of 2.58 ± 0.07 nm and an estimated layer number of ∼6. Drop-cast graphene/cellulose films became conductive above ∼250 µg cm−2 and reached sheet resistances of 3.8 kΩ/□ at 1.0 mg cm−2. This work positions aqueous LPE as a tolerant route for converting paired waste-derived carbon and cellulose streams into functional graphene nanosheet inks.