Efficient tandem electroreduction of nitrate into ammonia through coupling Cu single atoms with adjacent Co₃O₄

The nitrate (NO₃⁻) electroreduction into ammonia (NH₃) represents a promising approach for sustainable NH₃ synthesis. However, the variation of adsorption configurations renders great difficulties in the simultaneous optimization of binding energy for the intermediates. Though the extensively reported Cu-based electrocatalysts benefit NO₃⁻ adsorption, one of the key issues lies in the accumulation of nitrite (NO₂⁻) due to its weak adsorption, resulting in the rapid deactivation of catalysts and sluggish kinetics of subsequent hydrogenation steps. Here we report a tandem electrocatalyst by combining Cu single atoms catalysts with adjacent Co₃O₄ nanosheets to boost the electroreduction of NO₃⁻ to NH₃. The obtained tandem catalyst exhibits a yield rate for NH₃ of 114.0 mg \({}_{{{{{{\rm{NH}}}}}}_3}\) ${}_{{\mathrm{NH}}_3}$ h⁻¹ cm⁻², which exceeds the previous values for the reported Cu-based catalysts. Mechanism investigations unveil that the combination of Co₃O₄ regulates the adsorption configuration of NO₂⁻ and strengthens the binding with NO₂⁻, thus accelerating the electroreduction of NO₃⁻ to NH₃.