Two-dimensional titanium carbonitrides and their hydroxylated derivatives: Structural, electronic properties and stability of MXenes Ti3C2−xNx(OH)2 from DFTB calculations

The structural, electronic properties and stability of the new MXene compounds—two-dimensional pristine carbonitrides Ti3C2−xNx and their hydroxylated derivatives Ti3C2−xNx(OH)2 are studied by means of DFTB calculations. The genesis of the properties is discussed in the sequence: binary MXenes Ti3C2 (Ti3N2)→hydroxylated forms Ti3C2(OH)2 (Ti3N2(OH)2)→pristine MXene Ti3C2−xNx→hydroxylated Ti3C2−xNx(OH)2. All examined materials are metallic-like. The most favorable type of OH-covering is presented by the occupation of the hollow sites between three neighboring carbon (nitrogen) atoms. Two-dimensional MXene carbonitrides with random distribution of C and N atoms are found to be thermodynamically more favorable.