A carbon–nitrogen pathway in the ammonolysis of CO2-based polycarbonate networks

Carbonyl groups serve as key molecular junctions linking the carbon and nitrogen cycles in nature, mediating CO₂ assimilation and nitrogen incorporation into biomass. Translating this carbon–nitrogen coupling logic into synthetic systems offers a new framework for CO₂ utilization and sustainable material lifecycles. In this study, we establish a synthetic carbon–nitrogen pathway using CO₂-derived polymer systems. Cerium oxide (CeO₂) was employed as a catalyst to directly convert CO₂ into both cyclic monomers and cross-linkers, which were subsequently polymerized via ring-opening polymerization to form cross-linked polycarbonate networks. The resulting cross-linked polymer networks, which are soft and widely explored as functional and biodegradable materials, were efficiently decomposed in aqueous ammonia to yield a fertilizer-relevant mixture consisting of urea and regenerable molecular precursors. Importantly, these decomposition products were successfully reconverted into the original monomer and cross-linker using CO₂, thereby demonstrating a closed-loop chemical recycling system that integrates carbon capture and nitrogen utilization. This work provides a new strategy for converting CO₂ into soft, functional cross-linked polymer materials through the synthesis of monomers and cross-linkers, followed by their transformation into value-added nitrogen-containing products via polymer intermediates, highlighting a conceptually distinct approach to carbon–nitrogen cycle engineering in synthetic materials.