Electrocatalytic reduction of NO to NH3 in ionic liquids by P-doped TiO2 nanotubes

Designing advanced and cost-effective electro-catalytic system for nitric oxide (NO) reduction reaction (NORR) is vital for sustainable NH3 production and NO removal, yet it is a challenging task. Herein, it is shown that phosphorus (P)-doped titania (TiO2) nanotubes can be adopted as highly efficient catalyst for NORR. The catalyst demonstrates impressive performance in ionic liquid (IL)-based electrolyte with a remarkable high Faradaic efficiency of 89% and NH3 yield rate of 425 mu gmiddoth(-1)middotmg(cat.)(-1), being close to the best-reported results. Noteworthy, the obtained performance metrics are significantly larger than those for N-2 reduction reaction. It also shows good durability with negligible activity decay even after 10 cycles. Theoretical simulations reveal that the introduction of P dopants tunes the electronic structure of Ti active sites, thereby enhancing the NO adsorption and facilitating the desorption of *NH3. Moreover, the utilization of IL further suppresses the competitive hydrogen evolution reaction. This study highlights the advantage of the catalyst-electrolyte engineering strategy for producing NH3 at a high efficiency and rate.