Electronic and magnetic properties in nitrogen-doped 2D titanium carbides (MXenes): Insight from first-principles calculations

First-principles computations were performed to investigate the electronic and magnetic properties of pristine and nitrogen (N)-doped Ti2C and Ti3C2 MXenes. The effects of the concentrations and the distributions of nitrogen were considered. Our results show that N doping can enhance the conductivity of Ti2C and Ti3C2 MXenes, which both present metallic character under different N concentration. The metallicity of N-doped Ti2C and Ti3C2 MXenes indicates potential in metal-ion batteries. Also, N doping leads to an antiferromagnetic (AFM)-ferromagnetic (FM) transition for Ti3C2. The critical concentration from AFM to FM configurations is between 25% and 50%. Importantly, the magnetic state of the N-doped Ti3C2 monolayers is related with the N distribution. However, Ti2C systems maintain an AFM state regardless of N concentrations or N distributions. Thus, based on the basic understanding of the N-doped Ti2C and Ti3C2 monolayer, we believe that our findings would provide theoretical support for the multifaceted application of the C-based MXenes.