Efficient tandem electroreduction of nitrate into ammonia through coupling Cu single atoms with adjacent Co 3 O 4 .

The nitrate (NO 3 - ) electroreduction into ammonia (NH 3 ) represents a promising approach for sustainable NH 3 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 NO 3 - adsorption, one of the key issues lies in the accumulation of nitrite (NO 2 - ) 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 Co 3 O 4 nanosheets to boost the electroreduction of NO 3 - to NH 3 . The obtained tandem catalyst exhibits a yield rate for NH 3 of 114.0 mg NH 3 h -1 cm -2 , which exceeds the previous values for the reported Cu-based catalysts. Mechanism investigations unveil that the combination of Co 3 O 4 regulates the adsorption configuration of NO 2 - and strengthens the binding with NO 2 - , thus accelerating the electroreduction of NO 3 - to NH 3 .