First-principles prediction of two-dimensional MXene (V2C, Ti2C, and Mo2C) as the catalyst for ammonia decomposition

The geometric structure, electronic structure and dehydrogenation mechanism of NH3 adsorbed on three MXene (V2C, Ti2C, and Mo2C) surfaces were studied by combining density functional theory with periodic plate model. The calculation results of adsorption energy showed that the order of adsorption energy of NHx(x = 0–3) was Mo2C < V2C < Ti2C. The results of the transition states showed that the desorption of nitrogen atoms was the rate-limiting step of the whole reaction. The surface of V2C was more conducive to the decomposition of ammonia gas for hydrogen production, while the surface of Ti2C and Mo2C was susceptible to the adsorption poisoning of N atoms. The results of electron structure study showed that the strong interaction between d orbitals of transition metal atoms near Fermi level and molecular orbitals of ammonia made ammonia molecules activated in different degrees, showing high adsorption performance and catalytic activity.