High-Efficiency Ammonia Electrosynthesis on Anatase TiO_2- Nanobelt Arrays with Oxygen Vacancies by Selective...

Electrocatalytic reduction of nitrite to NH₃ provides a new route for the treatment of nitrite in wastewater, as well as an attractive alternative to NH₃ synthesis. Here, we report that an oxygen vacancy-rich TiO_2- nanoarray with different crystal structures self-supported on the Ti plate can be prepared by hydrothermal synthesis and by subsequently annealing it in an Ar/H₂ atmosphere. Anatase TiO_2- (A-TiO_2-) can be a superb catalyst for the efficient conversion of NO₂^- to NH₃; a high NH₃ yield of 12,230.1 ± 406.9 μg h^-1 cm^-2 along with a Faradaic efficiency of 91.1 ± 5.5% can be achieved in a 0.1 M NaOH solution containing 0.1 M NaNO₂ at -0.8 V, which also exhibits preferable durability with almost no decay of catalytic performances after cycling tests and long-term electrolysis. Furthermore, a Zn-NO₂^- battery with such A-TiO_2- as a cathode delivers a power density of 2.38 mW cm^-2 as well as a NH₃ yield of 885 μg h^-1 cm^-2.