Engineering local environment of ruthenium by defect-tuned SnO2 over carbon cloth for neutral-media N2 electroreduction

Abstract

Electrocatalytic N2 reduction reaction (NRR) is of great potential as a sustainable and alternative technique to the energy-intensive Haber-Bosch process for NH3 production. However, its practical applications are impeded by the low NH3 yield and Faradaic efficiency (FE) mainly due to the inert N≡N triple bond and the competing hydrogen evolution reaction (HER). Herein, ruthenium-doped defect-rich SnO2 nanoparticles on carbon cloth (Ru–SnO2/CC) are synthesized for efficient electrocatalytic NRR under ambient conditions. The catalysts exhibit an NH3 yield of 4.83 μg h−1 cm−2 with a FE of 17.01% at −0.2 V vs. reversible hydrogen electrode in 0.1 M Na2SO4. The integration of Ru species, SnO2 and oxygen vacancies leads a synergistic catalytic system, in which the semiconducting SnO2 particles not only stabilize the Ru active centers but also suppress the HER, while the oxygen vacancies in SnO2 lattice help to promote the N2 adsorption and enhance the activity of the Ru active centers. Overall, this synergy result in a unique local environment around the Ru active sites that favors the NRR process, which is further reinforced by the binder-free and facile electron transfer nature of CC, leading to the outstanding NRR catalytic activity and durability. These results outperform majority of the noble-metals-based electrocatalysts under similar conditions. This metal-doping tuned local environment manipulation may open up a promising avenue to the design and fabrication of efficient catalysts for N2 electroreduction.