Oxygen Vacancy-Enhanced Electrocatalytic Performances of TiO2 Nanosheets toward N2 Reduction Reaction

Electrocatalysts play vital roles in the enhancement of the catalytic performances of the reduction reaction from N-2 to NH3 at ambient conditions. This study reports oxygen vacancy-contained TiO2 nanosheets, which are explored as efficient electrocatalysts toward the N-2 reduction reaction (NRR). Oxygen vacancies are introduced and tuned by annealing the as-prepared TiO2 nanostructures under H-2/Ar atmosphere at different temperatures. The synergistic effect between the structural features and the morphological characteristics is the main reason for their high catalytic activities. Density functional theory calculations verify that the oxygen vacancies can greatly lower the energy barrier to activate the inert N(sic)N bonds for N-2 fixation. The 2D TiO2 nanosheets provide abundant active sites on their surface. The highest generation rate of NH3 is 2.83 times that of the as-prepared TiO2 nanostructures. The faradic efficiency is also increased. Furthermore, the oxygen vacancy-contained TiO2 electrocatalysts also show a high selectivity and high stability during cycling measurements. These findings provide not only an efficient electrocatalyst but also a new methodology to rational design of catalysts toward NRR under ambient conditions.