Strain-Induced Band Modulation, Work Function, and QTAIM Analysis of Surface O-Functionalized Ti2C MXene

Functionalized MXenes have wide applications in the fields of gas sensors, thermoelectric materials, and hydrogen storage. Strain-induced band engineering and the work function (WF) of Ti2CO2 MXene are investigated theoretically. The calculations reveal that Ti2CO2 MXenes are stable because of the negative Ecoh, and all the strains considered are within the elastic limit. For Ti2CO2 MXene, strain-induced blue shift of the Ti d state results in the transformation from a semiconductor to a metal. At about 4%, Ti2CO2 MXene transforms from an indirect band gap to a direct band gap. The decreased WF induced by the strain improves the power efficiency of Ti2CO2 MXene.