Human breath as a carbon dioxide source for organic synthesis.

The capture and utilization of low-concentration CO2 as a C1 feedstock for organic synthesis have emerged as important research areas. Although atmospheric CO2 is an ideal carbon source for sustainable organic transformations, its extremely low concentration (0.04%) presents a significant challenge to the development of efficient CO2 conversion processes. In this context, we turned our attention to human breath as an alternative CO2 source, which contains approximately 4% CO2. The capture and utilization of CO2 from human breath is also expected to play an important role in sustaining life in space, where readily available carbon sources are scarce and exhaled CO2 represents a valuable renewable carbon resource for life-support systems. Herein, we demonstrate that human breath can serve as a practical and readily available CO2 source for the efficient synthesis of urea compounds. Furthermore, the prepared urea compounds proved to be effective co-catalysts for the CO2 fixation with epoxides under pure CO2.