Oxygen Vacancies of Cr-Doped CeO₂ Nanorods That Efficiently Enhance the Performance of Electrocatalytic N₂ Fixation to NH₃ under Ambient Conditions

Abstract

Producing ammonia (NH₃) by electrocatalytic N₂ fixation is a promising and environmentally friendly strategy, in comparison to the Haber-Bosch process with high consumption of energy and CO₂ emissions. Because of the extremely high bond energy, it is indispensable to explore valid catalysts to activate the triple bond. In this paper, Cr-doped CeO₂ nanorods are developed to serve as non-noble-metal electrocatalysts for an electrocatalytic N₂ reduction reaction. Introducing Cr into the catalyst leads to an increase of the oxygen vacancies. In a 0.1 M Na₂SO₄ solution, the Cr_0.1CeO₂ nanorods achieve a high Faradaic efficiency (3.84%) and a large NH₃ yield (16.82 μg h^-1 mg_cat.^-1) at -0.7 V versus reversible hydrogen electrode. The Cr_0.1CeO₂ nanorods also exhibit high stability during the reaction.