COLLABORATIVE RESEARCH: Nano-Engineered MOF-Graphene Materials: New Perspectives for Reactive Adsorption and Catalysis

1133112/1133066 Bandosz/Gibbin活性碳具有较高的比表面积(通常为1,000-2,000 m2g-1)，是一种强大的物理吸附剂，但除高温外几乎没有催化活性。金属有机骨架(MOF)材料通常是有效的催化剂，但作为吸附剂的效果较差。最近，在概念验证中，我们成功地合成了GO/MOF纳米复合材料，并表明它通过表面反应和吸附相结合的方式非常有效地去除气体中的有毒气体(氨、硫化氢)。纳米复合材料去除有毒气体的能力远远超过MOF或氧化石墨单独的能力，对氨的初步结果表明，这些纳米复合材料的吸附容量比传统活性碳增加了300%或更多。本项目将对这种石墨烯/MOF和GO/MOF(统称为G/MOF)纳米复合材料进行联合实验和理论研究，目的是确定它们的形成机理、原子结构、孔结构以及催化和吸附性能，实际目标是设计出具有最佳吸附和催化性能的材料来去除有毒气体。作为以石墨素为基础的组件，将使用石墨、氧化石墨和剥离石墨。合成之后将进行表征。然后将研究NH3和H_2S单独以及与甲烷混合后与纳米复合材料的相互作用。这些体系的选择是基于吸附物的性质和化学性质的差异、在环境条件下对反应吸附的需求以及基于石墨烯的纳米复合材料的潜在检测能力。对于后者，可以利用电导率的变化。选择用于研究的MOF将包括具有潜在活性的铜、铬和铁中心的水稳定材料，如铜-BT或MIL-100。在实验计划的同时，将利用分子模拟(蒙特卡罗、混合反蒙特卡罗和分子动力学)和(从头算)密度泛函理论进行双尺度理论研究，以确定材料的原子结构、反应机理、反应吸附容量和吸附热的细节。这些理论结果将有助于将实验计划引向有希望的材料和条件。这项研究将对一类新型毒气脱除用G/MOF纳米复合材料的合成条件、原子结构和孔形态以及分离性能之间的关系提供基本的理解。这些新材料可能会在其他分离和传感设备中得到应用。广泛的表面表征和理论方法的应用将使我们更好地理解吸附剂和催化剂的表面化学。这项研究直接关系到开发新的战略，以设计有效的材料，通过反应吸附在环境条件下去除空气中的有毒气体。另一个重要的技术方面是这些材料作为气体传感器应用的可能性。如果在石墨层间插入小分子气体，电导率有望发生变化，这一现象可用于检测低浓度范围内的有毒气体。一项初步的氨在GO/MOF纳米复合材料上的探索性研究表明，其吸附容量大约是传统活性碳的三倍。因此，拟议的研究具有潜在的变革性。该项目将涉及来自市中心一所以科学为导向的高中的两名研究生、两名本科生和一名高中生。纽约州立大学是一个少数族裔服务机构，该项目将为代表不足群体的成员提供进行研究并获得博士学位的可能性。北卡罗来纳大学S数学与科学研究联盟(RAMS)暑期项目也将提供从代表不足人群中招收学生的机会。学生的整个教育体验将建立在研究和教育的融合上。

1133112/1133066Bandosz/GibbinsActivated carbons possess high surface area (typically 1,000-2,000 m2g-1) and are powerful physical adsorbents, but have little catalytic activity except at high temperatures. Metal-organic framework (MOF) materials are generally effective catalysts, but are less effective as adsorbents. Recently, in a proof of concept, we have succeeded in synthesizing a GO/MOF nanocomposite material, and shown that it is very effective in removing toxic gases (ammonia, hydrogen sulfide) from gas streams through a combination of surface reaction and adsorption. The capacity of the nanocomposites to remove toxic gases significantly exceeds that of either the MOF or graphite oxide alone, and preliminary results for ammonia suggest that these nanocomposites can achieve a 300% or more increase in adsorption capacity over conventional activated carbons. This project will be a joint experimental-theoretical study of such graphene/MOF and GO/MOF (collectively, G/MOF) nanocomposites, with the aim of determining their formation mechanism, atomic structure, pore structure and catalytic and adsorption properties, with the practical goal of designing materials with optimal adsorption and catalytic properties for the removal of toxic gases. As grapheme-based components graphite, graphite oxide and exfoliated graphite will be used. Syntheses will be followed by characterization. The interactions of NH3 and H2S, separately and mixed with methane, with the nanocomposites will then be investigated. These systems are chosen based on the properties and differences in the chemical nature of the adsorbates, the need for reactive adsorption under ambient conditions, and the potential detection capabilities of graphene-based nanocomposites. For the latter the changes in electrical conductivity can be employed. MOFs chosen for the study will include water stable materials with potentially active Cu, Cr and Fe sites, such as Cu-BT or MIL-100. In parallel with the experimental program, dual scale theoretical studies using molecular simulation (Monte Carlo, Hybrid Reverse Monte Carlo and Molecular Dynamics) and (ab initio) density functional theory will be carried out to determine details of the atomic structure of the materials, the reaction mechanism, reactive adsorption capacity and heats of adsorption. These theoretical results will help direct the experimental program towards promising materials and conditions. This research project will provide fundamental understanding of the relation between synthesis conditions, atomic structure and pore morphology, and separations performance for a new class of G/MOF nanocomposites that are designed for toxic gas removal. These novel materials may find application in other separations and in sensing devices. The broad spectrum of surface characterization and theoretical methods applied will lead to a better understanding of the surface chemistry of adsorbents and catalysts in general. The research is directly relevant to developing new strategies to design effective materials for removal of toxic gases from air at ambient conditions through reactive adsorption. Another important technical aspect is the possibility of applications of these materials as gas sensors. If small molecule gases are intercalated within the graphite interlayer space the electrical conductivity is expected to change, and this phenomenon can be used to detect toxic gases at low concentration range. A preliminary exploratory study of ammonia on a GO/MOF nanocomposite showed an approximately threefold increase in adsorption capacity over conventional activated carbons. Thus, the proposed research is potentially transformative. The project will involve two graduate students, two undergraduate researchers and one high school student from an inner city science-oriented high school. CCNY is a minority serving institution, and the project would provide the possibility for a member of an under-represented group to perform research and to earn the Ph.D. NCSU?s AGEP/Opt-Ed and ORNL?s Research Alliance in Math and Science (RAMS) summer program will also provide opportunities to recruit students from under-represented populations. The whole education experience of the students will be based on the integration of research and education.