The origin of low workfunctions in OH terminated MXenes

Hassan A. Tahini, Xin Tan, Sean C. Smith*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

68 Citations (Scopus)

Abstract

The workfunction is an important parameter that governs several electronic phenomena occurring at the surfaces and interfaces of materials. Here, we study MXenes, which are two dimensional metal carbides and nitrides. The workfunction is strongly dependent on the terminating functional groups which induce surface dipoles and Fermi level shifts. Here, we establish a correlation between the workfunction and the adsorbate's 2p band centres. Focusing on the OH terminated MXenes which have intrinsically low workfunctions, we show that a rigid relation between the 2p band centres and workfunctions exists which resembles a volcano plot. This imposes a limit on the lowest possible workfunctions of ∼1.2 eV and sets an optimum value of the 2p band centres at which this low workfunction can occur which we determined to be ∼-5.45 eV relative to the Fermi level. We demonstrate that neither strain modulation nor doping can achieve workfunctions lower than this.

Original languageEnglish
Pages (from-to)7016-7020
Number of pages5
JournalNanoscale
Volume9
Issue number21
DOIs
Publication statusPublished - 7 Jun 2017
Externally publishedYes

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