Ru-doped, oxygen-vacancy-containing CeO2 nanorods toward N2 electroreduction

Abstract

Electrochemical N₂ reduction (N₂RR) in aqueous solutions under ambient conditions is extremely challenging; thus, a rational design of electrocatalytic centers is required to effectively adsorb and activate N₂. Herein, we report Ru cluster-doped, oxygen vacancy-rich CeO₂ (Ru/CeO₂-V_O) nanorods as an efficient N₂ reduction electrocatalyst. The high-density oxygen vacancies inside CeO₂ are beneficial for the adsorption of N₂, and the unsaturated, low-valence Ru nanoclusters provide active sites for N₂ activation and subsequent electron transfer for N₂ reduction. The Ru/CeO₂-V_O catalyst exhibits a high ammonia production rate of 9.87 × 10⁻⁸ mmol s⁻¹ cm⁻² and a partial current density of 32 μA cm⁻² at −0.25 V versus reversible hydrogen electrode in 0.05 M H₂SO₄ solution, corresponding to a faradaic efficiency of 11.7%. Our work suggests that the synergistic effects between Ru nanoclusters and oxygen vacancies in CeO₂ for efficient N₂ fixation.