Theoretical investigation of capacitances in functionalised MXene supercapacitors M<sub> <i>n</i>+1</sub>C<sub> <i>n</i> </sub>O<sub>2</sub>, M = Ti, V, Nb, Mo
Mandira Das, Subhradip Ghosh
Abstract
Abstract MXene, the class of two-dimensional materials, has been found to be useful as potential electrode materials for electrochemical capacitors. Although experimental investigation on the electrochemical performances of a few MXenes have been carried out with exciting results, a complete understanding of their atomic scale behaviour is yet to be done. Using first-principles electronic structure methods, we perform a systematic investigation of the capacitances in pristine and functionalised MXenes <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msub> <mml:mrow> <mml:mtext>M</mml:mtext> </mml:mrow> <mml:mrow> <mml:mi>n</mml:mi> <mml:mo>+</mml:mo> <mml:mn>1</mml:mn> </mml:mrow> </mml:msub> <mml:msub> <mml:mrow> <mml:mtext>C</mml:mtext> </mml:mrow> <mml:mrow> <mml:mi>n</mml:mi> </mml:mrow> </mml:msub> <mml:msub> <mml:mrow> <mml:mtext>O</mml:mtext> </mml:mrow> <mml:mrow> <mml:mn>2</mml:mn> </mml:mrow> </mml:msub> </mml:math> where M = Ti, V, Nb and Mo. We provide results on each of the three sources of the capacitance and analyse them in detail for a complete understanding of their behaviour. The interpretation of the experimental results, wherever available, in the light of our computations, provides useful insights.