Effect of the sulfur termination on the properties of Hf2CO2 MXene

Abstract

First-principles calculations are performed to investigate the effect of surface termination of MXenes. In particular, we focus on the Hf2CO2 and Janus Hf2COS MXene. The present study confirms that the breaking of the structural symmetry generated by the chemical substitution of the O surface layer by S ones, promotes the tuning of the electronic properties. Hf2CO2 behaves as a semiconductor and its band gap is reduced, increasing the concentration of S atoms. Indeed, Hf2COS is metallic. In short, the present study confirms that tailoring the surface termination of MXene emerges as a suitable strategy to change the properties of MXene. Additionally, such a change in surface termination affects both vibrational frequencies and the rigidity of the Hf2CO2 MXene.