Solar-driven direct coupling of atmospheric CO2 with ammonia for urea synthesis
Zhiyong Zhang, Qing Huang, Yangen Xie, Boyang Zhang, Qi Zhao, Xingmiao Huang, Na Yang, Hongwei Ji, Chuncheng Chen, Hua Sheng, Jincai Zhao
Abstract
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. Current CO2 utilization relies on high-purity CO2, requiring energy-intensive capture and purification. This study developed a solar-powered heterojunction catalytic system that directly converts atmospheric CO2 with ammonia into urea.