标题： CO2在水合二氧化硅纳米孔中的吸附机制：从巨正则蒙特卡罗到经典和从头算分子动力学的见解 显示英文标题

标题： CO2 adsorption mechanisms in hydrated silica nanopores: Insights from grand canonical Monte Carlo to classical and ab initio molecular dynamics

摘要： 理解受限系统中的界面现象对于优化CO2捕获技术非常重要。在这里，我们通过结合巨正则蒙特卡罗（GCMC）、经典分子动力学（MD）和从头算分子动力学（AIMD）模拟的综合计算方法，对水合非晶二氧化硅纳米孔中的CO2吸附进行了全面研究。过量吸附等温线显示了显著的水合依赖性，随着水分含量从1%增加到15%，CO2的吸附量从7.6减少到2.6 mmol/g。吸附动力学分析表明存在一种独特的双峰过程，其特征是初始快速吸附随后是缓慢扩散限制的吸附，后者在较高水合水平下变得越来越占主导地位。经典MD模拟显示水合与CO2迁移率之间存在负相关关系，自扩散系数在整个研究的水合范围内均有所降低。密度剖面分析表明，CO2分布在水合诱导下从孔中心区域转变为靠近表面的区域，同时伴随着界面水网络的重排。值得注意的是，AIMD模拟捕捉到了之前未被认识到的化学过程，包括导致表面硅醇形成的质子转移机制，具有特征性的O-O距离为2.4-2.5{\AA }，以及通过水介导反应途径自发的CO2水合生成碳酸盐物种。这些发现表明，受限水在CO2捕获中既作为空间竞争者又作为反应介质，为碳捕获材料的设计提供了具有量子力学精度的分子层面的见解。 显示英文摘要

摘要： Understanding interfacial phenomena in confined systems is important for optimizing CO2 capture technologies. Here, we present a comprehensive investigation of CO2 adsorption in hydrated amorphous silica nanopores through an integrated computational approach combining grand canonical Monte Carlo (GCMC), classical molecular dynamics (MD), and ab initio molecular dynamics (AIMD) simulations. The excess adsorption isotherms reveal a marked hydration dependence, with CO2 uptake decreasing from 7.6 to 2.6 mmol/g as water content increases from 1 to 15 wt%. Analysis of adsorption kinetics demonstrates a distinctive bimodal process, characterized by rapid initial uptake followed by slower diffusion-limited adsorption, with the latter becoming increasingly dominant at higher hydration levels. Classical MD simulations reveal an inverse correlation between hydration and CO2 mobility, with self-diffusion coefficients decreasing across the studied hydration range. Density profile analysis indicates a hydration-induced transition in CO2 distribution from central pore regions to surface-proximate domains, accompanied by restructuring of interfacial water networks. Notably, AIMD simulations capture previously unrecognized chemical processes, including proton transfer mechanisms leading to surface silanol formation with characteristic O-O distances of 2.4-2.5 {\AA}, and spontaneous CO2 hydration yielding carbonate species through water-mediated reaction pathways. These findings demonstrate the dual role of confined water as both a spatial competitor and reaction medium for CO2 capture, providing molecular-level insights with quantum mechanical accuracy for design of carbon capture materials.