Title:	Hybrid funtional calculations of termination species in novel MXene nanosheets
DNr:	SNIC 2020/5-166
Project Type:	SNIC Medium Compute
Principal Investigator:	Martin Magnuson <martin.magnuson@liu.se>
Affiliation:	Linköpings universitet
Duration:	2020-04-01 – 2021-04-01
Classification:	10304 20501 20702
Homepage:	https://www.martinmagnuson.com/
Keywords:

Abstract

In the quest for new 2D materials outperforming graphene, research on other more advanced 2D materials has greatly intensified. The purpose of this proposal is to clarify what key factors of surface and interface bonding affect electronic transport properties of a new class of two-dimensional (2D) transition-metal carbides and nitrides called MXene. These semiconducting stacked Mn+1Xn (M is a transition metal and X is either carbon or nitrogen) nanosheets are emerging materials with large technological impact for applications in Li-ion batteries, super-capacitors, fuel and solar cells as well as in 2D-based electronics and transistors. The ultimate objective is to be able to tune and optimize the semiconducting and electronic transport properties of MXenes by investigating the influence of the functional -O, -OH, -OH2 and -F termination groups Tx, and intercalated ions (Li, Na and K) at the interfaces between stacked Mn+1Xn nanosheets. In particular, we investigate how the stacked Mn+1Xn layers in MXene should optimally be terminated to optimize different applications. In this project, relaxations and SCF calculations using VASP, WIEN2k and OCEAN DFT codes are made for the novel 2D MXene materials with different types of termination groups. The calculations are compared to existing experimental data produced in fruitful collaboration with Post. Doc. Joseph Halim, who defended his thesis at IFM at the end of 2018. Presently, we are working on several publications and need more time to finish the calculations. The first DFT results were published in the paper "Chemical Bonding in Carbide MXene Nanosheets" by Martin Magnuson, Joseph Halim and Lars-Åke Näslund; J. Elec. Spec. 224, 27-32 (2018). DOI: https://doi.org/10.1016/j.elspec.2017.09.006 For 2020, we have obtained several new beamtimes for XAS, XPS, XES to measure MXenes and other materials at MAX IV in Lund. Therefore, it is important to be able to directly compare the measurements with calculated results. My new PhD student Gabriel Nzulu also produces experimental data from MAX IV that needs to be supported by these type of DFT calculations.