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Superior Thermoelectric Performance of Ordered Double Transition Metal MXenes: Cr<sub>2</sub>TiC<sub>2</sub>T<sub>2</sub> (T = −OH or −F)

Ziang JingSchool of Electrical Engineering, State Key Laboratory of Electrical Insulation and Power Equipment, Xi’an Jiaotong University, Xi’an 710049, ChinaHangyu WangSchool of Electrical Engineering, State Key Laboratory of Electrical Insulation and Power Equipment, Xi’an Jiaotong University, Xi’an 710049, ChinaXianghui FengSchool of Electrical Engineering, State Key Laboratory of Electrical Insulation and Power Equipment, Xi’an Jiaotong University, Xi’an 710049, ChinaBing XiaoSchool of Electrical Engineering, State Key Laboratory of Electrical Insulation and Power Equipment, Xi’an Jiaotong University, Xi’an 710049, ChinaYingchun DingCollege of Optoelectronics Engineering, Chengdu University of Information Technology, Chengdu 610225, ChinaKai WuSchool of Electrical Engineering, State Key Laboratory of Electrical Insulation and Power Equipment, Xi’an Jiaotong University, Xi’an 710049, ChinaYonghong ChengSchool of Electrical Engineering, State Key Laboratory of Electrical Insulation and Power Equipment, Xi’an Jiaotong University, Xi’an 710049, China
2019en
ABI

Abstract

Using SCAN-rVV10+U, we show Cr2TiC2 and Cr2TiC2T2 (T = −F and −OH) MXenes are moderate band gap semiconductors mostly in the antiferromagnetic state. All investigated MXene structures show large Seebeck coefficients (>400 μV/K), especially Cr2TiC2 (>800 μV/K) and Cr2TiC2F2 (>700 μV/K). The hole relaxation time of p-type Cr2TiC2(OH)2 is found to be ∼8 ps, ensuring its superior electron transport properties in comparison to other investigated MXenes. It is also discovered that the surface functionalization could decrease the phonon thermal conduction and that Cr2TiC2(OH)2 has the smallest lattice thermal conductivity (∼6.5 W/m·K) and the largest electron thermal conduction (>50 W/m·K with n = 1019 cm–3). We predict the ZT value of p-type Cr2TiC2(OH)2 can reach 3.0 at 600 K with the maximum thermoelectric conversion efficiency of 20%. Overall, the thermoelectric property of Cr-based ordered double transition metal MXenes is far superior to that of any known two-dimensional structures in the MXene family.

Identifiers

DOI
10.1021/acs.jpclett.9b01827

Citations and references

Cited by 20 references
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