Investigating synergistic effect of controlling hierarchical pore structure and chemical modification on CO2 adsorption kinetics of reduced graphene oxide aerogel

IF 7.1 3区 材料科学 Q1 GREEN & SUSTAINABLE SCIENCE & TECHNOLOGY
Elahe Safaei , Zahra Talebi , Vahid Ghafarinia
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Abstract

The hierarchical pore structure of amine-functionalized reduced graphene oxide aerogels (rGOAs) plays a vital role in CO₂ adsorption. Herein, the self-assembly of rGOAs was investigated by adjusting graphene oxide concentration and reduction time of hydrothermal, and the effect of the hierarchical pore structure on adsorption capacity, kinetics, and rate-limiting models were discussed. The highest CO₂ adsorption (2.7 mmol/g) was achieved under hydrothermal synthesis conditions of 2 mg/mL graphene oxide concentration over 10 h. This high adsorption is attributed to the enhancement in meso and micro surface areas, as indicated by BET results (169 and 152 m2/g, respectively), the presence of adequate macropores (FE-SEM results), the presence of heteroatoms (N and O) according to XPS, FTIR, and EDX results, and a high NH/NT (-NH- spectral area/total amine spectral areas) ratio of 0.35. Additionally, the highest structural defect (1.17) was observed in RAMAN results. The Elovich model demonstrates good agreement with experimental data, indicating heterogeneous CO₂ adsorption. The high Sm/ST (micro surface area/micro + meso surface area) ratio (47%) and adequate macropores in the sample prepared with 2 mg/mL graphene oxide and 10 h, led to enhanced CO₂ physisorption. The high surface area increased the accessibility of active sites for chemisorption. The presence of macropores in this sample accelerates the mass transfer of CO₂ molecules, and the initial adsorption rate of the Elovich model (α = 0.032) is the highest. High graphene oxide concentration increased the surface barrier diffusion value due to decreased macropores. Intra-particle diffusion was identified as the rate-limiting kinetic model for CO₂ diffusion.

Abstract Image

研究控制分级孔结构和化学修饰对还原氧化石墨烯气凝胶CO2吸附动力学的协同效应
胺官能化还原氧化石墨烯气凝胶(rGOAs)的层次化孔结构在CO₂吸附中起着至关重要的作用。本文通过调整氧化石墨烯浓度和水热还原时间来研究氧化石墨烯的自组装,并讨论了分级孔结构对吸附容量、动力学和限速模型的影响。在2 mg/mL氧化石墨烯浓度的水热合成条件下,在10 h内获得了最高的CO₂吸附性(2.7 mmol/g)。这种高吸附性归因于介观和微观表面积的增强,如BET结果(分别为169和152 m2/g), FE-SEM结果显示存在足够的大孔,XPS, FTIR和EDX结果显示存在杂原子(N和O)。NH/NT (-NH-光谱面积/总胺光谱面积)之比高达0.35。此外,在RAMAN结果中观察到最高的结构缺陷(1.17)。Elovich模型与实验数据吻合较好,表明CO₂吸附不均匀。当氧化石墨烯浓度为2 mg/mL时,经过10 h处理后,样品的Sm/ST(微表面积/微+中表面积)比达到47%,且有足够的大孔,导致CO₂的物理吸附增强。高表面积增加了化学吸附活性位点的可及性。大孔的存在加速了CO₂分子的传质,Elovich模型(α = 0.032)的初始吸附速率最高。高氧化石墨烯浓度增加了表面势垒扩散值,减少了大孔隙。粒子内扩散被确定为CO₂扩散的限速动力学模型。
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来源期刊
CiteScore
5.80
自引率
6.40%
发文量
174
审稿时长
32 days
期刊介绍: Materials Today Sustainability is a multi-disciplinary journal covering all aspects of sustainability through materials science. With a rapidly increasing population with growing demands, materials science has emerged as a critical discipline toward protecting of the environment and ensuring the long term survival of future generations.
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