posted on 2024-01-11, 11:29authored byMandira Das, Subhradip Ghosh
Surface engineering in two-dimensional
(2D) materials has turned
out to be a useful technique to improve their functional properties.
By designing Janus compounds MM′C in the MXene family of compounds
M2C, where the two surfaces are constituted by two different
transition metals M and M′, we have explored their potentials
as electrodes in a supercapacitor with an acidic electrolyte. Using
density functional theory (DFT) in conjunction with the classical
solvation model, we have made an in-depth analysis of the electrochemical
parameters of three Janus MXenes, passivated by oxygen: NbVC, MnVC,
and CrMnC. Comparisons with the corresponding end-point MXenes Nb2C, V2C, Mn2C, and Cr2C are
also made. We find that the surface redox activity enhances due to
the formation of Janus, improving the charge storage capacities of
MXene electrodes significantly. Our analysis reveals that the improved
functionality has its root in the variations in the charge state of
one of the constituents in the Janus compound, which, in turn, has
its origin in the electronic structure changes due to surface manipulation.
Our work, which is the first on the electrochemical properties of
Janus MXenes for supercapacitor applications, suggests surface engineering
by forming appropriate Janus compounds as a possible route to extract
high energy density in MXene electrode–acidic electrolyte-based
energy storage devices.