Upcycling Plastic Waste into Graphitic Carbon - Identifying the Roles of Oxygen Content and sp2 Extent in Graphene Forms: Complementary Tests with LDPE and PET

这项拟议的研究旨在将消费塑料垃圾转化为高价值的石墨碳，用于电动汽车和可再生能源储存。目前，石油和煤是锂离子电池用石墨炭的前体。这些来源是不可再生的，需要大量的能源投入来进行处理。这项研究计划将检验这样一种假设，即塑料垃圾是石墨烯的高质量原料，因为与天然石墨相比，塑料垃圾的纯度和均匀性更高。将废塑料回收成高价值的石墨碳将改善回收经济，增加回收基础设施投资，增加回收劳动力，同时减少温室气体排放，提高公众的回收意识。这种向上循环的方法回收了塑料材料的具体能量成本，同时将碳作为固体捕获。作为一种新的“资源”，塑料垃圾将取代石油和煤炭作为原料，取代天然石墨的开采。回收塑料垃圾可以改变塑料回收经济，从而减少塑料污染，有助于可持续发展，并为循环碳经济增添一条新的道路。外联工作包括：a)通过为从事科学和工程研究的妇女提供暑期实习，增加多样性；b)通过为期一周的科学夏令营宣传K-12科学、技术、教育和教育；以及c)课后活动，以及d)通过YouTube视频向公众传播。这项拟议的研究旨在将消费塑料垃圾转化为高价值的石墨碳，用于电动汽车和可再生能源储存。低密度和高密度聚乙烯(LDPE、HDPE)和聚对苯二甲酸乙二酯(PET)为从各种废塑料原料中制备石墨炭带来了挑战：高脂肪(氢)含量(LDPE)和高氧含量(PET)。假设氧化石墨烯(GO)上的氧基团可以替代稳定过程来促进碳化反应，而2D石墨烯片层则促进石墨化过程中芳香族团簇的有序发展。热重分析(TGA)将被用作稳定化效果的衡量标准。拉曼光谱将量化石墨烯在碳化温度范围内的横向间距La以及非晶态和分子含量，以跟踪碳化过程。偏振光显微镜(PLM)将可视化前石墨化区域，通过图像分析量化将在这个项目中开发。广角X射线散射将测量石墨化前(晶前)阶段的芳香结构域生长。在出现石墨化结构后，将使用标准X射线衍射(XRD)来确定晶格参数d002、La、Lc和石墨化指数g。将进行一系列实验，以共同表征石墨化程度与GO氧含量、石墨烯(GR)sp2面积和周长，以验证反应力场(ReaxFF)分子动力学模拟。透射电子显微镜(TEM)和选区电子衍射(SAED)将在纳米尺度上提供石墨化质量和微观均匀度的局部测量。电导率将通过使用兰德尔电路模型的阻抗光谱分析来评估微晶的连接性。GO稳定器的一个潜在含义是石墨化速度将增加，从而实现能源节约和二氧化碳减少。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

The proposed study seeks to upcycle consumer plastic waste into high value graphitic carbons for electric vehicles and renewable energy storage. Presently, petroleum and coal are the precursors for graphitic carbons used in Li-ion batteries. These sources are non-renewable and require substantial energy input for their processing. This research program will test the hypothesis that plastic waste constitutes a high-quality feedstock for graphene given its higher purity and uniformity compared to natural graphite. Upcycling waste plastic into high-value graphitic carbons will lead to improved recycling economics, increased recycling infrastructure investment, and growth of the recycling workforce while reducing greenhouse gas emissions and raising public awareness for recycling. This upcycling approach recovers the embodied energy cost of the plastic materials while trapping the carbon as a solid. As a new “resource,” plastic waste would eliminate petroleum and coal as feedstocks and displace mining for natural graphite. Upcycling plastic waste could transform the plastics recycling economy and thereby reduce plastic pollution, contributing to sustainability and adding a new path to a circular carbon economy. Outreach efforts include a) increasing diversity by summer internships for women in science and engineering research, b) promoting K-12 STEM through one-week science camps; and c) after-school events along with d) public dissemination via YouTube videos. The proposed study seeks to upcycle consumer plastic waste into high value graphitic carbons for electric vehicles and renewable energy storage. Low- and high-density polyethylene (LDPE, HDPE) and polyethylene terephthalate (PET) bracket the challenges of forming graphitic carbons from varied waste plastic feedstocks: high aliphatic (hydrogen) content (LDPE) and high oxygen content (PET). It is hypothesized that oxygen groups on graphene oxide (GO) can act as a substitute for the stabilization process required to promote carbonization over cracking reactions, while the 2D graphene sheet promotes ordered development of aromatic clusters during graphitization. Thermo-gravimetric analysis (TGA) will be used as a measure of stabilization effectiveness. Raman spectroscopy will quantify graphene lateral spacing La across the carbonization temperature range along with amorphous and molecular content to track carbonization progress. Polarized light microscopy (PLM) will visualize pre-graphitic domains, quantified by image analysis to be developed in this project. Wide angle X-ray scattering will gauge aromatic domain growth at pre-graphitic (pre-crystalline) stages. Upon emergence of graphitic structure, standard X-ray diffraction (XRD) will be used to determine crystal lattice parameters d002, La, Lc and graphitization index g. A sequence of experiments will be conducted to collectively characterize the level of graphitization with GO oxygen content and graphene (GR) sp2 area and peripheral length, to validate reactive force field (ReaxFF) molecular dynamics simulations. Transmission electron microscopy (TEM) and selected area electron diffraction (SAED) will provide localized measures of graphitic quality and microscopic uniformity at the nanoscale. Electrical conductivity will assess crystallite connectedness via impedance spectroscopy using a Randall circuit model. A potential implication of the GO stabilizer is that the rate of graphitization will increase, thereby realizing energy savings and CO2 reduction.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.