Functional Group Effects on the Photoelectronic Properties of MXene (Sc2CT2, T = O, F, OH) and Their Possible Photocatalytic Activities

Kuangwei Xiong,Guang Yang,Xin Xu,Haijun Zhang,Zhongfei Liu,Shaowei Jin,Peihong Wang

doi:10.1038/s41598-017-15233-8

Kuangwei Xiong, Guang Yang + Show 5 more

Open Access

https://doi.org/10.1038/s41598-017-15233-8

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Abstract

In view of the diverse functional groups left on the MXene during the etching process, we computationally investigated the effects of surface-group types on the structural, electronic and optical properties of Sc2CT2 (T = -O, -OH, -F) MXenes. For all geometries of the Sc2CT2 MXenes, the geometry I of Sc2CT2, which has the functional groups locating above the opposite-side Sc atoms, are lowest-energy structure. Accordingly, the energetically favorable Sc2CF2-I, Sc2CO2-I and Sc2C(OH)2-I were selected for further evaluation of the photocatalytic activities. We found that the Sc2CO2-I is metallic, while Sc2CF2-I and Sc2C(OH)2 are semiconductors with visible-light absorptions and promising carrier mobilities. Compared with the Sc2C(OH)2-I, the Sc2CF2-I has not only more suitable band gap (1.91 eV), but also the higher redox capability of photo-activated carriers, which should have better photocatalytic performance.

Highlights

During the etching process, “A” atoms were removed and functional groups (-O, -OH, or -F) were left on the surface of MXene to passivate the outer-layer metal atoms
Among the variously functionalized MXenes, only M2CO2 (M = Ti, Zr, Hf) with geometry I, which have the functional group located above the opposite-side metal atoms, have appropriate band gaps (0.92 ∼ 1.75 eV) for photocatalytic applications
We firstly check the relative stabilities of the optimized MXenes with different geometries

Summary

Introduction

“A” atoms were removed and functional groups (-O, -OH, or -F) were left on the surface of MXene to passivate the outer-layer metal atoms. The suitable band gaps of surface functionalized MXenes strongly indicate their visible-light absorption and possible photocatalytic applications. Among the variously functionalized MXenes, only M2CO2 (M = Ti, Zr, Hf) with geometry I, which have the functional group located above the opposite-side metal atoms, have appropriate band gaps (0.92 ∼ 1.75 eV) for photocatalytic applications. The effects of surface group on the electronic and optical properties of Sc2CT2 (T = -O, -OH, -F) MXenes and the possibilities of their photoelectronic applications are yet to be addressed. The computational results suggest that Sc2CF2-I with -F group locating at the opposite position of outer metal atoms have appropriate band gaps of 1.91 eV, visible-light absorption and strong redox capability of photo-induced excitons. Based on our calculation results, the fluorinated Sc2C MXene could be a promising candidate for high-performance photocatalysts

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