Heterointerface‐Enhanced Active Hydrogen Generation in Ru/RuOx/CNTs for Nitrate Reduction to Ammonia at Low Overpotentials

Ru/RuOx/CNTs heterostructured materials are synthesized using an in situ method. The Ru─RuOx heterostructure facilitates active hydrogen dissociation, leading to excellent catalytic performance in nitrate reduction, with ammonia as the primary product at low overpotentials. The process achieves Faradaic efficiencies of ammonia exceeding 90% and a production rate of 1.16 mmol h-1 cm-2 within a potential range of 0.25-0 V (vs RHE). Differential electrochemical mass spectrometry (DEMS) confirms the pathway by which nitrate is reduced to ammonia. Electron Paramagnetic Resonance (EPR) is used to detect the presence of *H during the electrochemical NO3 -RR. Furthermore, the high bifunctional catalytic activity of this material is demonstrated in a nitrate-hydrazine reforming electrolysis cell, powered by a 2.0 V solar cell, which achieves an ammonia production rate of 0.82 mmol h-1 under natural sunlight. While the ammonia in the reforming electrolysis cell is precipitated and separated, yielding a total of 4.7 g of struvite, realizing the transformation of solar energy into fertilizer products. These findings provide valuable insights for the design of efficient heterostructured materials and electrocatalytic system for the conversion of nitrate.