Nitrogen-Doped Ti3C2 MXene: Mechanism Investigation and Electrochemical Analysis

Nitrogen doping has been proven to be a facile modification strategy to improve the electrochemical performance of 2D MXenes, a group of promising candidates for energy storage applications. However, the underlying mechanisms, especially the positions of nitrogen dopants, and its effect on the electrical properties of MXenes, are still largely unexplored. Herein, a comprehensive study is carried out to disclose the nitrogen doping mechanism in Ti3C2 MXene, by employing theoretical simulation and experimental characterization. Three possible sites are found in Ti3C2Tx (T = F, OH, and O) to accommodate the nitrogen dopants: lattice substitution (for carbon), function substitution (for -OH), and surface absorption (on -O). Moreover, electrochemical test results confirm that all the three kinds of nitrogen dopants are favorable for improving the specific capacitance of the Ti3C2 electrode, and the underlying factors are successfully distinguished. By revealing the nitrogen doping mechanisms in Ti3C2 MXene, this work provides theoretical guidelines for modulating the electrochemical properties of MXene materials for energy storage applications.