Cuprous ionic liquid engineering combined with preorganized hydrogen-bond donors for enhanced carbon monoxide capture

Carbon monoxide (CO) is a toxic but valuable precursor for organic synthesis. Thus, CO capture is an important and sustainable process. Here, a strategy of cuprous ionic liquid engineering combined with preorganized hydrogen-bond donors (HBDs) was first developed to form a series of functional deep eutectic solvents (DESs) for enhanced CO capture via promoting cooperation, and the stepped sorption isotherms with a characteristic threshold “gate-opening” pressure were obtained. It was found that the enhanced absorption capacity (up to 220%) and enhanced working capacity (up to 310%) can be reached by DESs with preorganized HBDs. Quantum-chemical calculations and spectroscopic investigations revealed that cooperative interactions and preorganized benzenediols were the reason for equimolar capacities. Additionally, at least 17 absorption–desorption cycles with high CO capacity could be reached, indicating excellent reversibility. Thus, easy preparation, high Cu(I) efficiency, and high working capacity make these DESs an alternative way for CO capture.