Cu/Cu _x O/Graphdiyne Tandem Catalyst for Efficient Electrocatalytic Nitrate Reduction to Ammonia

Abstract The electrocatalytic reduction reaction of nitrate (NO ₃ ⁻ ) to ammonia (NH ₃ ) is a feasible way to achieve artificial nitrogen cycle. However, the low yield rate and poor selectivity toward NH ₃ product is a technical challenge. Here a graphdiyne (GDY)‐based tandem catalyst featuring Cu/Cu _x O nanoparticles anchored to GDY support (termed Cu/Cu _x O/GDY) for efficient electrocatalytic NO ₃ ⁻ reduction is presented. A high NH ₃ yield rate of 25.4 mg h ⁻¹ mg _cat. ⁻¹ (25.4 mg h ⁻¹ cm ⁻² ) 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 ₃ ⁻ to NH ₃ catalysts in the alkaline media. Electrochemical measurements and density functional theory reveal that the NO ₃ ⁻ preferentially attacks Cu/Cu _x O, and the GDY can effectively catalyze the reduction of NO ₂ ⁻ to NH ₃ . 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.