Solar-driven direct coupling of atmospheric CO2 with ammonia for urea synthesis

Current CO2 utilization depends on high-purity CO2, necessitating energy-intensive capture and purification from air. Herein, we present a practical system that selectively converts atmospheric CO2 with ammonia into urea using solar energy as the sole input. This system is enabled by a heterostructure composed of an indium–porphyrin metal–organic framework and UiO-66-NH2, which harness ambient O2 to promote rather than suppress CO2 reduction. As a result, it achieves a CO production rate of 272.1 μmol·g−1·h−1 directly from air, which is competitive compared to the systems that rely on high-purity CO2. Moreover, coupling atmospheric CO2 reduction with ammonia oxidation enables direct air-to-urea conversion with high selectivity. A scaled-up prototype operating under natural sunlight and open-air conditions achieves a urea production rate of 32.4 μmol·g−1·h−1. This work integrates atmospheric CO2 capture, solar-driven conversion, and product collection within a single, scalable platform, offering a practical route for carbon utilization under real-world conditions.