In Situ Dynamic Reconstruction Asymmetric P─Co─O/OH Sites for Sustainable Gram-Level Electrocatalytic Ammonia Production.

Abstract

The electrochemical conversion of nitrite/nitrate (NO_x ^-) to ammonia (NH₃) offers a sustainable route for NH₃ production, particularly coupled with efficient air plasma. However, balancing catalyst activity/stability for gram-level NH₃ production remains major challenges. In this study, we report a low-crystallinity phosphorus-doped cobalt electrode (P─Co/NF) for efficient and stable NH₃ synthesis via NO₂ ^- reduction, achieving an impressive NH₃ yield rate of 414.51 mg h^-1 cm^-2 and outstanding long-term stability of 1000 h. Comprehensive characterizations and theoretical calculations reveal that the dynamically evolved P─Co/Co(OH)₂ heterostructure with asymmetric P─Co─O/OH active sites simultaneously optimizes NO₂ ^- activation and water dissociation. The synergistic interplay between P─Co and Co(OH)₂ layer facilitates sufficient *H supply and moderate intermediate adsorption, thereby suppressing H₂ evolution. To enable direct air-to-NH₃ conversion, a complete system is established by integrating electrocatalysis with microwave plasma and intermittent solar power, achieving an average NH₃ yield of 1.19 g per day with Faradaic efficiency >90%. When scaled up to a 100 cm² flow cell, the system delivers an NH₃ production rate of 4.97 g h^-1. This work provides a paradigm for designing dynamic asymmetric sites that overcome activity-stability tradeoff under industrial-level current density, paving the way toward the decentralized and sustainable NH₃ production.