Electrochemical ammonia oxidation reaction on defect-rich TiO nanofibers: Experimental and theoretical studies

Ammonia is a promising platform molecule for the future renewable energy infrastructure owing to its high hydrogen content and carbon-free nature. The development of inexpensive and efficient catalysts for ammonia electro-oxidation reaction (AOR) is essential to ammonia-based economy. In this paper, a self-supporting AOR catalyst of ultra-elongated defective TiO nanofibers grown on Ti foil (TiO/Ti foil) is designed. By the comparisons of electrochemical measurement results, the efficient AOR activity of TiO/Ti foil has been presented in alkaline ammonia solution when the voltage is higher than 0.4 V. Density functional theory (DFT) calculations illustrate that the surface oxygen vacancies in TiO play a vital role in facilitating AOR activity by reducing the energy barrier in the rate-determining ∗HNNH 2 formation step and also promoting N 2 desorption. These results demonstrate that defective TiO is a promising low-cost and stable catalyst for AOR, which is a potential electrode for efficient H 2 production by ammonia electrolysis and direct ammonia fuel cells. TiO nanofibers grown on Ti foil are used as the catalyst for ammonia electro-oxidation reaction. Oxygen vacancies on the surface of TiO crystal can facilitate catalytic activity, and promote N 2 desorption, and enhance electrochemical stability. • Ultra-elongated defective TiO nanofibers grown on Ti foil was synthesized. • The composites was used as the catalyst for ammonia electro-oxidation reaction. • Better electrochemical stability than Pt was revealed in alkaline ammonia solution. • DFT calculations illustrate the reaction pathway and the effect of oxygen vacancies.