10.1021/acsami.6b08444.s001 Juan I. Paredes Juan I. Paredes José M. Munuera José M. Munuera Silvia Villar-Rodil Silvia Villar-Rodil Laura Guardia Laura Guardia Miguel Ayán-Varela Miguel Ayán-Varela Ana Pagán Ana Pagán Salvador D. Aznar-Cervantes Salvador D. Aznar-Cervantes José L. Cenis José L. Cenis Amelia Martínez-Alonso Amelia Martínez-Alonso Juan M. D. Tascón Juan M. D. Tascón Impact of Covalent Functionalization on the Aqueous Processability, Catalytic Activity, and Biocompatibility of Chemically Exfoliated MoS<sub>2</sub> Nanosheets American Chemical Society 2016 stability hydrothermal annealing procedure cell proliferation tests chemical derivatization material ce-MoS 2 benefit acetic acid groups Chemically Exfoliated MoS 2 Nanosheets Chemically exfoliated MoS 2 chemical modification strategies ce-MoS 2 nanosheets acetic acid-functionalized nanosheets chemical exfoliation step 1 T phase 2 H phase MoS 2 unit 2016-10-05 17:20:47 Journal contribution https://acs.figshare.com/articles/journal_contribution/Impact_of_Covalent_Functionalization_on_the_Aqueous_Processability_Catalytic_Activity_and_Biocompatibility_of_Chemically_Exfoliated_MoS_sub_2_sub_Nanosheets/3985776 Chemically exfoliated MoS<sub>2</sub> (ce-MoS<sub>2</sub>) has emerged in recent years as an attractive two-dimensional material for use in relevant technological applications, but fully exploiting its potential and versatility will most probably require the deployment of appropriate chemical modification strategies. Here, we demonstrate that extensive covalent functionalization of ce-MoS<sub>2</sub> nanosheets with acetic acid groups (∼0.4 groups grafted per MoS<sub>2</sub> unit) based on the organoiodide chemistry brings a number of benefits in terms of their processability and functionality. Specifically, the acetic acid-functionalized nanosheets were furnished with long-term (>6 months) colloidal stability in aqueous medium at relatively high concentrations, exhibited a markedly improved temporal retention of catalytic activity toward the reduction of nitroarenes, and could be more effectively coupled with silver nanoparticles to form hybrid nanostructures. Furthermore, in vitro cell proliferation tests carried out with murine fibroblasts suggested that the chemical derivatization had a positive effect on the biocompatibility of ce-MoS<sub>2</sub>. A hydrothermal annealing procedure was also implemented to promote the structural conversion of the functionalized nanosheets from the 1T phase that was induced during the chemical exfoliation step to the original 2H phase of the starting bulk material, while retaining at the same time the aqueous colloidal stability afforded by the presence of the acetic acid groups. Overall, by highlighting the benefits of this type of chemical derivatization, the present work should contribute to strengthen the position of ce-MoS<sub>2</sub> as a two-dimensional material of significant practical utility.