Interaction of imidazolium based ionic liquid electrolytes with carbon nitride electrodes in supercapacitors; a step forward for understanding electrode–electrolyte interaction

[Display omitted] •Imidazolium based ionic liquids (ILs) are investigated on C2N surface for their potential in supercapacitors.•The nature of interaction between electrode and electrolyte is evaluated through NCI and QTAIM analysis.•The HOMO-LUMO energy gap of the electrolyte@C2N complexes decreases upon adsorption of ILs.•The highest interaction between electrolyte–electrode is observed in case of 1,3-dimethylimidazolium chloride (MIC) IL. Ionic liquids (ILs) are considered as an emerging class of electrolytes finding their applications in energy storage devices due to wide electrochemical windows, nonflammability, low volatility, and high thermal and chemical stability. The interaction of three ionic liquids i.e., 1,3-dimethylimidazolium chloride (MIC), 1,3-disulfonic acid imidazolium nitrate (DIN), 1-Ethyl-3-methylimidazolium tetrafluoroborate (EMI) with C2N surface is evaluated for better understanding electrode–electrolyte interaction in supercapacitors. The interaction of electrolytes on C2N electrode is studied through interaction energy analysis, non-covalent interactions (NCI) analysis and quantum theory of atoms in molecule (QTAIM) analyses. Electronic properties are investigated through natural bond orbital (NBO), frontier molecular orbital (FMOs), density of states and electron density analyses. Interaction energies calculated for the most stable geometry of the studied electrolytes are −13.83 kcal/mol (DIN@C2N), −25.90 kcal/mol (EMI@C2N), and −26.94 kcal/mol (MIC@C2N). NBO analysis reveals that an appreciable amount of charge is transferred from surface to ionic liquids, and these results are further supported by EDD analysis. Moreover, FMO analysis unveils that 2.04 eV decrease in energy gap of MIC@C2N complex. We strongly believe that this study provides a deep insight in better understanding the electrode–electrolyte interactions, which play vital role in various application such as super-capacitors, batteries, and fuel cells.