First-principles insights into ammonia decomposition on WC (0001) surface terminated by W and C

Abstract

In order to investigate the adsorption and dehydrogenation process of ammonia on WC (0001) surfaces terminated by W and C atoms, the density functional theory (DFT) was used along with periodic slab models. All possible adsorption configurations and energies of relevant intermediates on WC (0001) surfaces were identified. The results of the adsorption energy and transition states showed that the C-terminated WC surface was more favorable for hydrogen production by the decomposition of ammonia. Conversely, the WC surface terminated by W atoms was susceptible to be poisoned by the adsorbed N atoms, leading to the combinative desorption of N atoms as the rate-limiting step in the entire reaction. The unique differences between WC (0001) surfaces terminated by W and C atoms suggested that a structure-sensitive reaction was ammonia decomposition over the WC catalyst.