Band gap modification in doped MXene: Sc₂CF₂

Abstract

We report the modification of the band gap in the Sc2CF2 MXene monolayer through C atom substitution by Si, Ge, Sn, F, S, N, B, and B + N.

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.…”

“…Because delaminated MXene films, are relatively thin and show better electrochemical properties than the un-delaminated MXene flakes. [122] Moreover, some nonmetallic elements such as sulfur have a high theoretical capacity, so the capacity of the doped material is likely to increase. Therefore, to boost the electrical properties of LIBs with MXene as electrode materials, it is significant to study the surface of MXene and control the layer restacking of MXene.…”

“…[54] However, Eames et al found that the larger radius of Na + ions than Li + ions, still make MXenes to be inferior in electrochemical performance when used as an electrode material in sodium ion batteries. [122] S-doped Ti 3 C 2 T x shows excellent performance in sodium-sulfur batteries (138 mA h g −1 at 500 mA g −1 after 2000 cycles). Lithium-sulfur batteries Crumpled N-Ti 3 C 2 T x /S Annealing in melaine and melt-diffusion method 588 mA h g −1 (77%) at 0.2 C after 500 cycles [258] Ti 2 CT x /S Melt-diffusion method 723 mA h g −1 (66.3%) at 0.5 C after 650 cycles [228] Ti 3 C 2 T x /rGO/S Solution mixing and Solution mixing 878.4 mA h g −1 (77%) at 0.5 C after 300 cycles [143] Ti 3 C 2 T x /Meso-C/S Solvothermal, annealing, and melt-diffusion method 704.6 mA h g −1 (57.5%) at 0.5 C after 300 cycles [66] Ti 3 C 2 T x /CNT/S Solution mixing and melt-diffusion method ≈770 mA h g −1 (63%) at 0.2 C after 250 cycles [153] Ti 3 C 2 T x /glass fiber Filtration to form separator 721 mA h g −1 (87.9%) at 0.3 C after 100 cycles [229] Ti 3 C 2 T x /polypropylene Filtration to form separator 495 mA h g −1 (66.6%) at 1 C after 500 cycles [74] www.advmatinterfaces.de sodium-ion battery, the electrochemical performance was clearly improved.…”

“…[112] Apart from the properties mentioned above, MXenes show numerous attractive properties, such as adsorption, [111,113,114] ferromagnetism, [30,115] antibacterial activity, [116,117] thermoelectric property, [118] gas separation performance, [119] photothermalconversion capability, [120] etc. 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.…”

“…Doping by some nonmetallic elements reduces the band gap of MXene, which increases the conductivity. [122] Moreover, some nonmetallic elements such as sulfur have a high theoretical capacity, so the capacity of the doped material is likely to increase. Whereas, some metallic elements used to dope MXene have a greater impact on magnetic properties.…”