Environmental degradation of graphene-based materials: a case study with saprotrophic fungi

Graphene-based materials (GBMs) are frequently used in new devices reaching themarketplace daily. Theproduction, useanddisposal of such devices involves the potential release of GBMs into the environment with unpredictable fates and impacts of thematerials.We posit that the biodegradability of GBMs is a fundamental characteristic to understand the environmental fate of these materials. In this study, the biodegradability of few-layer graphene (FLG), graphene oxide (GO) and a composite material containing reduced GO (rGO) was assessed by incubating the materials in cultures of white-rot (Phanerochaete chrysosporium,Bjerkandera adusta) and litter-degrading (Morchella esculenta) fungi. FLG, GO and rGO were also subjected to lignin peroxidase, the enzyme released by white-rot fungi in order to degrade the natural subtrate, lignin. We observed that all fungi, but not lignin peroxidase, oxidized the GBMs. The results suggest that white-rot and other fungi are able to initiate biodegradation of GBMs, arguing against the hypothesis of GBM accumulation in terrestrial environments, and pointing towards remediation approaches.