LAUSR

Amine‐scrubbing‐based chemical absorption is an effective and industrialized technology for CO2 capture, but the challenge lies in developing efficient and energy‐saving absorbents. Here we present a rationally designed amine absorbent, N‐(2‐hydroxypropyl)‐N‐ethylethylenediamine (HPEEDA), featuring simultaneous functionalized ethyl and hydroxypropyl groups on a tertiary amine. Experimental results demonstrate that HPEEDA exhibits high efficiency in both CO2 absorption and desorption, while offering great energy‐saving advantages during regeneration. The structure–activity relationship between HPEEDA and CO2 capture is revealed through the systematic examination of the disassembled HPEEDA blends. Quantitative experiments and theoretical calculations elucidate the CO2 capture mechanism of HPEEDA, highlighting the critical role of intermolecular proton transfer in promoting CO2 capture. This rationally designed amine absorbent that breaks the CO2 absorption–desorption trade‐off is expected to advance underway efforts toward large‐scale CO2 capture.