Magnetron sputtering tuned π back-donation sites over metal oxides for enhanced electrocatalytic nitrogen reduction

As an environmentally-benign and sustainable option for NH3 synthesis, the electrochemical nitrogen reduction reaction (NRR) is expected to replace the traditional Haber-Bosch process. Transition metals with empty d-orbitals achieve NRR activity via a pi back-donation process. However, the problem in overcoming hydrogen evolution reaction (HER) competition makes the exploration of transition metal-based catalysts with relatively inferior HER activity worthwhile. The challenges lie in designing a rational structure for efficient NRR. Herein, Ni3+ and oxygen vacancies were synergistically integrated on NiO@TiO2 by magnetron sputtering, which provide this transition-metal oxide-based (TMO-based) material with pi back-donation behavior. Accordingly, NiO@TiO2 exhibited NH3 yield (similar to 10.75 mu g h(-1) cm(cat.)(-2)) and faradaic efficiency (similar to 9.83%), which are nearly 10-fold higher relative to those of TiO2 in neutral media. This work provides an efficient strategy for engineering pi back-donation sites, and holds great potential in exploring new TMO-based electrocatalysts.

Automated summary

This work presents a strategy for efficient NRR through integrating Ni3+ and oxygen vacancies on NiO@TiO2 via magnetron sputtering. The resulting material exhibits excellent pi back-donation behavior and shows high NH3 yield and faradaic efficiency in neutral media, indicating great potential for TMO-based electrocatalysts.