The separation of CO₂ from N₂ remains a highly challenging task in postcombustion CO₂ capture processes, primarily due to the relatively low CO₂ content (3–15%) compared to that of N₂ (70%). This challenge is particularly prominent for carbon-based adsorbents that exhibit relatively low selectivity. In this study, we present a successfully implemented strategy to enhance the selectivity of composite aerogels made of reduced graphene oxide (rGO) and functionalized polymer particles. Considering that the CO₂/N₂ selectivity of the aerogels is affected on the one hand by the surface chemistry (offering more sites for CO₂ capture) and fine-tuned microporosity (offering molecular sieve effect), both of these parameters were affected in situ during the synthesis process. The resulting aerogels exhibit improved CO₂ adsorption capacity and a significant reduction in N₂ adsorption at a temperature of 25 °C and 1 atm, leading to a more than 10-fold increase in selectivity compared to the reference material. This achievement represents the highest selectivity reported thus far for carbon-based adsorbents. Detailed characterization of the aerogel surfaces has revealed an increase in the quantity of surface oxygen functional groups, as well as an augmentation in the fractions of micropores (<2 nm) and small mesopores (<5 nm) as a result of the modified synthesis methodology. Additionally, it was found that the surface morphology of the aerogels has undergone important changes. The reference materials feature a surface rich in curved wrinkles with an approximate diameter of 100 nm, resulting in a selectivity range of 50–100. In contrast, the novel aerogels exhibit a higher degree of oxidation, rendering them stiffer and less elastic, resembling crumpled paper morphology. This transformation, along with the improved functionalization and augmented microporosity in the altered aerogels, has rendered the aerogels almost completely N₂-phobic, with selectivity values ranging from 470 to 621. This finding provides experimental evidence for the theoretically predicted relationship between the elasticity of graphene-based adsorbents and their CO₂/N₂ selectivity performance. It introduces a new perspective on the issue of N₂-phobicity. The outstanding performance achieved, including a CO₂ adsorption capacity of nearly 2 mmol/g and the highest selectivity of 620, positions these composites as highly promising materials in the field of carbon capture and sequestration (CCS) postcombustion technology.

中文翻译：

---

类似于石墨烯/聚合物气凝胶形态，可提高燃烧后 CO2 捕获过程的 CO2/N2 选择性

_{在燃烧后CO 2捕集过程中，将CO 2}与N ₂分离仍然是一项极具挑战性的任务，这主要是因为与N _{2 (70%) 相比，CO 2}含量相对较低(3–15%) 。对于选择性相对较低的碳基吸附剂来说，这一挑战尤为突出。在这项研究中，我们提出了一种成功实施的策略，以提高由还原氧化石墨烯（rGO）和功能化聚合物颗粒制成的复合气凝胶的选择性。考虑到气凝胶的CO ₂ /N ₂选择性一方面受到表面化学（提供更多CO ₂捕获位点）和微调微孔性（提供分子筛效应）的影响，这两个参数都受到影响合成过程中原位。所得到的气凝胶在25℃和1atm的温度下表现出改进的CO ₂吸附能力和显着降低的N ₂吸附，导致与参考材料相比，选择性提高了10倍以上。这一成就代表了迄今为止报道的碳基吸附剂的最高选择性。气凝胶表面的详细表征表明，由于改进的合成方法，表面氧官能团数量增加，微孔（<2 nm）和小介孔（<5 nm）比例增加。此外，还发现气凝胶的表面形态发生了重要变化。参考材料的表面富含直径约为 100 nm 的弯曲皱纹，导致选择性范围为 50-100。相比之下，新型气凝胶表现出更高程度的氧化，使其更硬且弹性更小，类似于皱巴巴的纸形态。这种转变，连同改变的气凝胶中功能化的改进和微孔性的增强，使气凝胶几乎完全疏N ₂，选择性值范围为470至621。这一发现为理论上预测的弹性之间的关系提供了实验证据。石墨烯基吸附剂及其CO ₂ /N ₂选择性性能。它引入了对 N ₂恐惧问题的新视角。所实现的出色性能，包括近2 mmol/g的CO ₂吸附容量和620的最高选择性，使这些复合材料成为碳捕获和封存（CCS）燃烧后技术领域极具前景的材料。