Cu/CuO/Graphdiyne Tandem Catalyst for Efficient Electrocatalytic Nitrate Reduction to Ammonia.

The electrocatalytic reduction reaction of nitrate (NO ) to ammonia (NH) is a feasible way to achieve artificial nitrogen cycle. However, the low yield rate and poor selectivity toward NH product is a technical challenge. Here a graphdiyne (GDY)-based tandem catalyst featuring Cu/CuO nanoparticles anchored to GDY support (termed Cu/CuO/GDY) for efficient electrocatalytic NO reduction is presented. A high NH yield rate of 25.4 mg h mg (25.4 mg h cm) with a Faradaic efficiency of 99.8% at an applied potential of -0.8 V versus RHE using the designed catalyst is achieved. These performance metrics outperform most reported NO to NH catalysts in the alkaline media. Electrochemical measurements and density functional theory reveal that the NO preferentially attacks Cu/CuO, and the GDY can effectively catalyze the reduction of NO to NH. This work highlights the efficacy of GDY as a new class of tandem catalysts for the artificial nitrogen cycle and provides powerful guidelines for the design of tandem electrocatalysts.