Surface Oxygen Species Modulation of Cu2O/Cu Foam for Enhanced Nitrate-to-Ammonia Conversion

The electrochemical reduction of nitrate for ammonia production is recognized as a viable method to support a sustainable artificial nitrogen cycle. Extensive research has been focused on enhancing the performance and selectivity of electrocatalysts for NO 3 - RR (nitrate reduction reaction). In this study, we show that modifying the surface oxygen species via thermal treatment and dispersant addition is an effective way to improve the NO 3 - RR performance of Cu 2 O/CF. Using advanced spectroscopic methods, we show that thermal treatment and dispersant addition can greatly boost the generation of oxygen vacancies and hydroxyl groups on the surface of Cu 2 O/CF. Electrocatalytic reaction rate experiment, in-situ FT-IR, DEMS analyses and DFT calculations further suggest that oxygen vacancies on the Cu 2 O/CF surface promote the adsorption and conversion of nitrate and its intermediate, nitrite. Meanwhile, hydroxyl groups promoted the selective hydrogenation of NO to NH 3 . Our findings highlight the essential role of surface oxygen species in NO 3 - RR and provide a foundation for designing advanced electrocatalysts through surface engineering approaches.