As emerging atomically ultrathin metal compounds, MXenes
show great
promise for catalytic and nanoelectronic applications due to their
abundant surface terminations and high metallic conductivity. However,
the tendency for interlayer adhesion and suffering from environmental
disturbances significantly limit their endurance and efficiency. Herein,
via conducting first-principles calculations, we explore surface passivation
and exfoliation of MXenes via polymers, which have been experimentally
proven to promote the performance. Nine kinds of monomers together
with a typical MXene, Ti3C2T2 (T
= none, O, F, OH, F0.5O0.5), as prototype composites
are explored with respect to the adsorption and charge transfer associated
with energetics and chemical redox, respectively. Our work shows that
the naked Ti3C2 MXene has strong ability to
cleave and decompose the monomers. Surface-functionalized Ti3C2F2, Ti3C2FO, and Ti3C2O2 have a weak binding with monomers
through only van der Waals force, whereas Ti3C2(OH)2 also exhibits strengthened binding for some monomers.
Specific functional groups in the monomer, such as the halogen, sulfur,
and hydroxyl groups, or a relatively planar aromatic structure, largely
contribute to the adsorption. We reveal that the functionalization
through polymers would alter the carriers’ density via interfacial
charge transfer in MXenes. While the naked Ti3C2 and Ti3C2(OH)2 donate electrons
to the polymers, Ti3C2F2, Ti3C2FO, and Ti3C2O2 receive small amounts of electrons transferred from the polymer,
highly depending on the types of the monomers. The varying ability for charge transfer and exfoliation energy of different
monomers imply great flexibility for designing polymers to exfoliate
the MXene and modulate the carrier densities, which are highly desired
for altering the conductivity, dielectric properties, and promoting
endurance.