Ti₂O₃ Nanoparticles with Ti³⁺ Sites toward Efficient NH₃ Electrosynthesis under Ambient Conditions

Electrocatalytic nitrogen reduction reaction (NRR) enabled by introducing Ti 3+ defect sites into TiO 2 through a doping strategy has recently attracted widespread attention. However, the amount of Ti 3+ ions is limited due to the low concentration of dopants. Herein, we propose Ti 2 O 3 nanoparticles as a pure Ti 3+ system that performs efficiently toward NH 3 electrosynthesis under ambient conditions. This work has suggested that Ti 3+ ions, as the main catalytically active sites, significantly increase the NRR activity. In an acidic electrolyte, Ti 2 O 3 achieves extraordinary performance with a high NH 3 yield and a Faradaic efficiency of 26.01 μg h –1 mg –1 cat. and 9.16%, respectively, which are superior to most titanium-based NRR catalysts recently reported. Significantly, it also demonstrates a stable NH 3 yield in five consecutive cycles. Theoretical calculations uncovered that the enhanced electrocatalytic activity of Ti 2 O 3 originated from Ti 3+ active sites and significantly lowered the overpotential of the potential-determining step.