In silico design, building and gas adsorption of nano-porous graphene scaffolds
In silico design, building and gas adsorption of nano-porous graphene scaffolds
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DOI：
10.1088/1361-6528/abbe57
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发表时间：
2021-01-22
期刊：
影响因子：
3.5
通讯作者：
Tozzini, Valentina
中科院分区：
文献类型：
--
作者：
Bellucci, Luca;Delfino, Francesco;Tozzini, Valentina
石墨烯基纳米多孔材料（GNM）对于需要大比表面积（SSA）的所有那些应用是潜在有用的，大比表面积（SSA）是二维石墨烯的典型，但在体维度中实现。这样的应用包括例如气体存储和分选、催化和电化学能量存储。虽然通过使用纳米-微米颗粒作为模板在微孔材料中实现了结构的合理控制，但是严格在纳米尺度下具有孔隙率的GNM的受控生产或甚至表征仍然存在问题。这些通常使用纳米薄片作为前体的分散体来生产，导致对最终结构的控制很少，这反过来反映了用于计算机模拟的结构模型构建中的问题。在这项工作中，我们描述了一种策略，建立这些材料的模型与预定的结构特性（SSA，密度，孔隙率），利用分子动力学模拟，蒙特卡罗方法和机器学习算法。我们的策略受到真实的合成过程的启发：从随机分布的薄片开始，我们在飞行中包括缺陷，穿孔，结构变形和边缘饱和，并且在结构细化之后，我们获得具有给定结构特征的逼真模型。我们发现之间的关系的结构特征和尺寸分布的起始鳞片悬浮液和最终的结构，这可以给更有效的合成路线的迹象。随后，我们给出了一个完整的表征模型与H-2吸附，从中我们提取的结构参数和重量密度之间的定量关系。我们的研究结果定量地阐明了表面和边缘相对量在确定H-2吸附中的作用，并提出了克服这些材料作为吸附剂的固有物理限制的策略。我们在软件工具中实现了模型构建和分析程序，可应要求免费提供。
Graphene-based nano-porous materials (GNM) are potentially useful for all those applications needing a large specific surface area (SSA), typical of the bidimensional graphene, yet realized in the bulk dimensionality. Such applications include for instance gas storage and sorting, catalysis and electrochemical energy storage. While a reasonable control of the structure is achieved in micro-porous materials by using nano-micro particles as templates, the controlled production or even characterization of GNMs with porosity strictly at the nano-scale still raises issues. These are usually produced using dispersion of nano-flakes as precursors resulting in little control on the final structure, which in turn reflects in problems in the structural model building for computer simulations. In this work, we describe a strategy to build models for these materials with predetermined structural properties (SSA, density, porosity), which exploits molecular dynamics simulations, Monte Carlo methods and machine learning algorithms. Our strategy is inspired by the real synthesis process: starting from randomly distributed flakes, we include defects, perforation, structure deformation and edge saturation on the fly, and, after structural refinement, we obtain realistic models, with given structural features. We find relationships between the structural characteristics and size distributions of the starting flake suspension and the final structure, which can give indications for more efficient synthesis routes. We subsequently give a full characterization of the models versus H-2 adsorption, from which we extract quantitative relationship between the structural parameters and the gravimetric density. Our results quantitatively clarify the role of surfaces and edges relative amount in determining the H-2 adsorption, and suggest strategies to overcome the inherent physical limitations of these materials as adsorbers. We implemented the model building and analysis procedures in software tools, freely available upon request.