On the nanoscale interface, electronic structure, and optical properties of nanocarbon-reinforced calcium silicate hydrates

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This study presents results from quantum chemical simulations of the synergetic interaction, electronic structure, and optical properties of calcium-silicate hydrates (C-S-H) reinforced by graphene-nanoribbons and single-walled carbon nanotubes (SWCNT). The calculations show that C-S-H/graphene-nanoribbon and C-S-H/SWCNT composites are stabilized by electrostatic interaction due to the charge transfer from Ca ions at the interface of C-S-H to the nearby C atoms of the graphene-nanoribbon and SWCNT. Removing Ca ions at the interface drastically decreases the strength of interaction into a weak van der Waals type. The Bader charge transfer analysis and electron distribution topology further confirm these results. Generally, the electronic states of the graphene-nanoribbon and SWCNT are shifted to lower energy in the complex. The electronic structure of graphene-nanoribbon and SWCNT is susceptible to the Ca ions-rich C-S-H environment. The composites’ overall absorption spectra can be considered superimposed of the isolated nanocarbon and C-S-H except in the lower energy region due to charge transfer and realignment of energy states. The results presented here reveal the bonding mechanism of the C-S-H with nanocarbon at the fundamental level. This work serves as a reference for the nanoengineering cement-based material with nanocarbon for the next-generation smart infrastructure.