Negative emission technologies, including direct air capture (DAC) of carbon dioxide, are now considered essential for mitigating climate change, but existing DAC processes tend to have excessively high energy requirements, mostly associated with sorbent regeneration. Here, we demonstrate a promising approach to DAC that combines atmospheric CO₂ absorption by an aqueous oligopeptide (e.g., glycylglycine) with bicarbonate crystallization by a simple guanidine compound (e.g., glyoxal-bis-iminoguanidine). In this phase-changing system, the peptide and the guanidine compounds work in synergy, and the cyclic CO₂ capacity can be maximized by matching the pK_a values of the two components. Compared with glycine, the simpler amino acid congener, the cyclic CO₂ capacity of the glycylglycine peptide combined with glyoxal-bis-iminoguanidine is twice as high (0.16 mol/mol). The resulting DAC process has a significantly lower regeneration energy compared with state-of-the-art solvent-based DAC technologies.

如今，负排放技术（包括二氧化碳的直接空气捕获（DAC））被认为对缓解气候变化至关重要，但是现有的DAC工艺往往对能量的需求过高，主要与吸附剂的再生有关。在这里，我们展示了一种有前途的DAC方法，该方法将低聚肽水溶液（例如，甘氨酰甘氨酸）对大气的CO ₂吸收与简单的胍化合物（例如，乙二醛-双-亚氨基胍）的碳酸氢盐结晶结合在一起。在该相变系统中，肽和胍化合物协同作用，并且通过匹配p K _a可以使环状CO ₂容量最大化。这两个组件的值。与更简单的氨基酸同源物甘氨酸相比，甘氨酰甘氨酸肽与乙二醛-双-亚氨基胍结合使用时的环状CO ₂容量要高两倍（0.16 mol / mol）。与最先进的基于溶剂的DAC技术相比，最​​终的DAC工艺具有更低的再生能量。