The electrocatalytic nitrate conversion of ammonia at ambient conditions provides not only a solution for restoring the imbalance in the global nitrogen cycle but also a sustainable alternative for the Haber-Bosch process. However, large-scale and efficient application of electrocatalytic denitrification has been limited by the lack of active catalysts with a high selectivity of nitrate reduction to N2. In this work, we present a one-step solution processed synthetic strategy at low temperature to prepare carbon-nanobelts-supported uniform Cu and Pd nanoclusters. It is found that Cu catalyzed the formation of carbon nanobelts. The prepared samples were used for the green synthesis of ammonia from nitrate by electrocatalysis. For the nitrate reduction reaction (NO3RR), Cu-Pd/C nanobelts show higher activity than Cu/C nanobelts, achieving a high yield of ammonia of 220.8 μg mgcat-1 h-1 with a Faradaic efficiency (FE) of 62.3% at -0.4 V vs RHE (reversible hydrogen electrode), while for the nitrite reduction reaction (NO2RR), a high FE of 95% at -0.2 V vs RHE can be obtained for Cu/C nanobelts with the yield of ammonia increased with the negative shift of the applied potentials. Theoretical calculations demonstrated that Pd and Cu are responsible for hydrogen evolution reaction (HER) and NO3RR, respectively.
Keywords: Cu nanoparticle; Pd nanocluster; ammonia production; carbon nanobelt; nitrate electroreduction.