Zhao Meng, Huang Liang, Gao Yanshan, Wang Ziling, Zhu Xuancan, Wang Qiang, O'Hare Dermot
College of Environmental Science and Engineering, Beijing Forestry University, Beijing, 100083, China.
State Key Laboratory of Efficient Production of Forest Resources, Beijing Forestry University, Beijing, 100083, China.
Adv Sci (Weinh). 2025 Jun 30:e07756. doi: 10.1002/advs.202507756.
Emerging as a critical technology for atmospheric carbon dioxide (CO) removal, the mass deployment of direct air capture (DAC) demands breakthrough innovations in efficient and stable adsorbent materials that simultaneously achieve high capacity, oxidative durability, and low cost. Herein, a hydroxyl-rich MgAl layered double hydroxide (LDH) support is developed via aqueous miscible organic solvent treatment, circumventing energy-intensive calcination while engineering mesopores for efficient polyethyleneimine (PEI) loading. The optimized 60 wt.% PEI modified MgAl-CO AMO-LDH achieves a CO uptake of 3.92 mmol g under simulated wet air at 25 °C and retains 90.8% capacity over 20 cycles. Crucially, the abundant surface hydroxyls of uncalcined LDH, validated by H Nuclear Magnetic Resonance and in situ X-ray Photoelectron Spectroscopy, form hydrogen bonds with PEI, suppressing oxidative degradation. After 3 h at 120 °C in simulated air, PEI-LDH retains a CO capacity of 1.06 mmol g, significantly outperforming PEI/mixed metal oxide and conventional silica-based adsorbents. In situ Diffuse Reflectance Infrared Fourier Transform Spectroscopy further reveals that hydroxyl-mediated amine anchoring minimizes water co-adsorption. This work establishes a dual strategy of hydroxyl preservation and mesopore engineering to design cost-effective DAC adsorbents, achieving both high capacity and exceptional stability under realistic operating conditions.
作为一种用于去除大气中二氧化碳（CO₂）的关键技术，直接空气捕获（DAC）的大规模部署需要在高效稳定的吸附材料方面取得突破性创新，这些材料要同时具备高容量、氧化耐久性和低成本。在此，通过与水混溶的有机溶剂处理开发了一种富含羟基的MgAl层状双氢氧化物（LDH）载体，避免了能源密集型的煅烧过程，同时设计了中孔以实现高效的聚乙烯亚胺（PEI）负载。优化后的60 wt.% PEI改性MgAl-CO AMO-LDH在25°C的模拟湿空气中实现了3.92 mmol g⁻¹的CO₂吸收量，并在20个循环中保持了90.8%的容量。至关重要的是，通过¹H核磁共振和原位X射线光电子能谱验证，未煅烧的LDH丰富的表面羟基与PEI形成氢键，抑制了氧化降解。在120°C的模拟空气中放置3小时后，PEI-LDH的CO₂容量保持在1.06 mmol g⁻¹，明显优于PEI/混合金属氧化物和传统的二氧化硅基吸附剂。原位漫反射红外傅里叶变换光谱进一步表明，羟基介导的胺锚固作用使水的共吸附最小化。这项工作建立了羟基保留和中孔工程的双重策略，以设计具有成本效益的DAC吸附剂，在实际操作条件下实现了高容量和卓越的稳定性。
