The thermal and electrical properties of the promising semiconductor MXene Hf2CO2

Abstract

With the growing interest in low dimensional materials, MXenes have also attracted considerable attention recently. In this work, the thermal and electrical properties of oxygen-functionalized M2CO2 (M = Ti, Zr, Hf) MXenes are investigated using first-principles calculations. Hf2CO2 is determined to exhibit a thermal conductivity better than MoS2 and phosphorene. The room-temperature thermal conductivity along the armchair direction is determined to be 86.25~131.2 Wm−1 K−1 with a flake length of 5~100 μm. The room temperature thermal expansion coefficient of Hf2CO2 is 6.094 × 10−6 K−1, which is lower than that of most metals. Moreover, Hf2CO2 is determined to be a semiconductor with a band gap of 1.657 eV and to have high and anisotropic carrier mobility. At room temperature, the Hf2CO2 hole mobility in the armchair direction (in the zigzag direction) is determined to be as high as 13.5 × 103 cm2V−1s−1 (17.6 × 103 cm2V−1s−1). Thus, broader utilization of Hf2CO2, such as the material for nanoelectronics, is likely. The corresponding thermal and electrical properties of Ti2CO2 and Zr2CO2 are also provided. Notably, Ti2CO2 presents relatively lower thermal conductivity but much higher carrier mobility than Hf2CO2. According to the present results, the design and application of MXene based devices are expected to be promising.

Electronic properties and applications of MXenes: a theoretical review

“…along the armchair (zigzag) flake length of 1-100µm [55]. Among Sc 2 CT 2 (T= F, O, OH), Sc 2 C(OH) 2 is predicted to be a candidate for thermoelectric application at elevated temperatures more than 300 K due to a relatively good Seebeck coefficient, high electrical conductivity, and very low lattice thermal conductivity [53].…”

“…Theoretically, many applications have been proposed for MXenes in electronic [39][40][41][42][43], magnetic [44][45][46][47][48], optical [49,50], thermoelectric [51][52][53][54][55][56], and sensing devices [57], as well as being new potential materials for catalytic and photocatalytic reactions [58][59][60][61][62][63], hydrogen storage media [64,65], and nanoscale superconductivity [66]. Some of MXenes are predicted to be topological insulators with large band gaps involving only d orbitals [67][68][69][70][71].…”

Enhanced thermal properties of poly(vinylidene fluoride) composites with ultrathin nanosheets of MXene

“…[18][19][20][21][22] Similar to graphene and BN, two dimensional MXenes have good physical properties, such as mechanical strength, electrical conductivity and thermal conductivity. [23][24][25][26][27][28] Some previous studies have reported the incorporation of MXenes (Ti 3 C 2 T x ) into different polymer matrices, such as ultrahigh-molecular polyethylene (UMWPE), polypyrrole (PPy), and polyvinyl alcohol (PVA).…”

MXene‐Based Composites: Synthesis and Applications in Rechargeable Batteries and Supercapacitors

“…[106] The thickness difference of Ti 3 C 2 T x flakes leads to different resistances and transmittances; therefore, their optoelectronic properties are interesting. Moreover, the performance of the MXenes can be improved by making peculiar morphologies (e.g., hollow MXenes [121] ), changing the local structure of MXenes (e.g., doping by other atoms [122,123] ), modifying surfaces (e.g., heat treatment [38] ), increasing the MXene layer spacing (e.g., inserting cations or organic molecules [48,124] ), etc. [107,108] It is well known that titanium hydroxide and/or titania show good photocatalytic activities.…”

“…[52,53] Moreover, MXenes have demonstrated massive storage power with intercalated polyvalent cations, for instance, Ca 2+ ions, [54] Mg 2+ ions, [55,56] and Al 3+ ions. [38] The composites prepared by combining MXenes with different types of materials (e.g., stable carbon materials [57,58] ) are worth digging into to potentially improve their performances. [38] The composites prepared by combining MXenes with different types of materials (e.g., stable carbon materials [57,58] ) are worth digging into to potentially improve their performances.…”