Nitrogen doping has proved to be a convenient modification strategy to improve the electrochemical performance of two-dimensional MXene materials, and a large number of candidate materials for energy storage applications have been reported. However, its underlying mechanism, especially the site of nitrogen dopants and its effect on the electrochemical performance of MXene materials, remains largely to be explored.

Achievements

Recently, Central South University of ZhengMing Sun Professor in the top international journal Advanced Functional Materials published entitled " Nitrogen-Doped Ti 3 C 2  MXene: Electrochemical Mechanism Investigation and the Analysis " paper. In this paper, through theoretical simulation and experimental characterization, the  nitrogen doping mechanism in Ti 3 C 2 T x MXene is fully revealed . Three possible sites were found in Ti 3 C 2 T x to bind nitrogen dopants: lattice substitution (carbon), functional substitution (-OH) and surface adsorption (-O). The electrochemical test results show that the three nitrogen dopings are beneficial to increase the specific capacitance of Ti 3 C 2 T x electrode, and successfully distinguish the influencing factors. This work reveals Ti 3 C 2 T xThe nitrogen doping mechanism in the paper provides theoretical guidance for adjusting the electrochemical performance of MXene materials for energy storage applications.

Figure  1 Schematic diagram of  N- doped MXene .

Figure  2  calculates the electron density and vibration density .

Picture  3 N- doped MXene morphology .

Picture  4 N- doped MXene structure .

Picture  5 Electrochemical performance of N- doped MXene.

Table  1 The  mechanism and potential influencing factors of nitrogen doping on the total capacitance of MXene materials.

in conclusion

Discloses of Ti . 3 C 2 T X   MXene three possible combinations nitrogen doping substance site : carbon atoms LS and -OH functional groups FS and a -O end associated SA , respectively, can be formed -1.31 eV , - 4.71 eV and -2.87 eV . The electrochemical test of the prepared MXene electrode shows that the total capacitance can be divided into two parts : the diffusion control part is mainly related to the redox reaction of the bulk element, which mainly depends on the oxidation state of Ti element in Ti 3 C 2 T x  MXene These are strongly influenced by layer spacing, surface absorption and functional groups.

Original link:

https://onlinelibrary.wiley.com/doi/full/10.1002/adfm.202000852

Source: MXene Academic 

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