Colloidal stabilization of hydrophobic InSe 2D nanosheets in a model environmental aqueous solution and their impact on

Semiconductor InSe 2D nanomaterials have emerged as potential photoresponsive materials for broadly distributed photodetectors and wearable electronics technologies due to their high photoresponsivity and thermal stability. This paper addresses an environmental concern about the fate of InSe 2D nanosheets when disposed and released into the environment after use. Semiconducting materials are potentially reactive and often form environmentally damaging species, for example reactive oxygen and nitrogen species, when degraded. InSe nanosheets are prepared using a semi bottom-up approach which involves a reaction between indium and selenium precursors at elevated temperature in an oxygen-free environment to prevent oxidation. InSe nanosheets are formed as a stable intermediate with micrometer-sized lateral dimensions and a few monolayer thickness. The InSe 2D nanosheets are obtained when the reaction is stopped after 30 minutes by cooling. Keeping the reaction at elevated temperature for a longer period, for example 60 minutes leads to the formation of InSe 3D nanoparticles of about 5 nm in diameter, a thermodynamically more stable form of InSe. The paper focuses on the colloidal stabilization of InSe nanosheets in an aqueous solution that contains epigallocatechin gallate (EGCG), a natural organic matter (NOM) simulant. We show that EGCG coats the surface of the hydrophobic, water-insoluble InSe nanosheets