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1. Improved Graphitization of Lignin by Templating Using Graphene Oxide Additives

   https://doi.org/10.1021/acsabm.4c01122  

   Ike, Sandra N; Vander_Wal, Randy L (December 2024, ACS Applied Bio Materials)

   Techniques to improve the graphitization of lignin, the second most abundant natural polymer, are in great demand as a viable means to obtain cost- effective and less energy-intensive graphite for various applications. In this work, we report the effects of two-dimensional nanomaterials, graphene oxide (GO) and its derivative, reduced graphene oxide (RGO), used as templating agents for the graphitization of alkali-derived lignin. The hypothesis is that during heat temperature treatment, the GO additives act as a template that allows the lignin matrix to align on its basal planes through π−π interactions. In addition, possible chemical bonding between the GO additives and lignin may extend the two planar frameworks. Results from X-ray diffraction and Raman spectroscopy showed improved graphitic quality in the lignin-GO and lignin-RGO samples compared to pure lignin at 2500 °C. Transmission electron microscopy images and selected area electron diffraction patterns also revealed ordered nanostructures and defined polycrystalline patterns in the lignin-GO and lignin-RGO samples. This work presents a method to synthesize graphitic-like materials using carbon-based templates with the advantage that there is no need for further purification of the final material as in the case of transition metal catalysts. 

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2. Distinguishing physical vs. chemical templating mechanisms for inducing graphitization in novolac matrix

   https://doi.org/10.1016/j.cartre.2025.100480  

   Ike, Sandra N; Wal, Randy Vander (April 2025, Carbon Trends)

   Meunier, V (Ed.)

   ur previous work investigated the templating ability of graphene oxide-derived additives to induce graphitization of the novolac matrix. The findings led to two working hypotheses: the additives act as templates that promote matrix aromatic alignment to their basal planes during carbonization (referred to here as physical templating) in addition to forming radical edge sites that bond to the decomposing matrix (referred to here as chemical templating). However, results mainly underscored the role of functional groups on the GO additives (chemical templating). The aim of this current work seeks to differentiate the contributions of the operative mechanisms on graphitization. To study this, 2D materials with minimal oxygen functionalization, graphene and hexagonal boron nitride (hBN) were used as templates to induce graphitization of novolac matrix. First, the optimum weight percent of the 2D materials was determined with the composite graphitic quality measured by X-ray diffraction and Raman spectroscopy. Results revealed that hBN did not induce graphitization of novolac and was attributed to the absence of a sp² framework in hBN, unable to provide the crucial π-π interactions with the aromatic rings of the matrix. In contrast, the graphene additives mirrored one another and showed improved graphitization of the novolac. From these results, it was surmised that both mechanisms are operative; while physical templating offers control over long-range order in the form of crystallite height, chemical templating contributes to carbon reorganization and lateral growth extent. 

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3. Upcycling Plastic Waste into Graphite Using Graphenic Additives for Energy Storage: Yield, Graphitic Quality, and Interaction Mechanisms via Experimentation and Molecular Dynamics

   https://doi.org/10.1021/acssuschemeng.3c07783  

   Gharpure, Akshay; Kowalik, Malgorzata; Vander Wal, Randy L.; van Duin, Adri C.T. (March 2024, ACS Sustainable Chemistry & Engineering)

   Subramaniam, B. Executive Editor (Ed.)

   This research presents pioneering work on transforming a variety of waste plastic into synthetic graphite of high quality and purity. Six recycled plastics in various forms were obtained – including reprocessed polypropylene, high-density polyethylene flakes, shredded polyethylene films, reprocessed polyethylene (all obtained from Pennsylvania Recycling Markets Center), polystyrene foams and polyethylene terephthalate bottles (both sourced from a local recycling bin). The waste plastics were carbonized in sealed tubing reactors. The study shows that this versatile process can be used on a mix of waste plastics in a variety of recycled forms to obtain a uniform graphitic carbon phase, hence addressing the challenges of separation and transportation faced by the plastic recycling industry. The conversion yield to elemental carbon for recycled plastics was improved by up to 250% by using graphene oxide (GO) additives. Five different grades of GO and graphene were used to gain insights into the interaction mechanisms between plastics and GO during pyrolysis. The effect of GO additives on carbonization was analyzed using thermogravimetric analysis / differential scanning calorimetry and ReaxFF-based reactive molecular dynamics simulations. The obtained cokes were graphitized at 2500 ℃ and the graphitic quality of the synthetic graphites was analyzed using X-ray diffraction, transmission electron microscopy, and Raman spectroscopy. The plastic waste-derived synthetic graphites exhibit remarkable graphitic quality with crystallite sizes comparable with a model graphitizable material – anthracene coke. The thin, flake-like morphology and nanostructure featuring well-stacked contiguous lamellae make these graphitic carbons highly promising candidates for energy storage applications. Based on our experiments and atomistic-scale simulations we propose interaction mechanisms between the plastic polymers and the graphenic additives that explain the chemical conversion pathways for GO-assisted waste plastic carbonization and graphitization. 

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4. TEMPLATING INDUCED GRAPHITIZATION BY GRAPHENE OXIDE DERIVED ADDITIVES: PHENOLIC RESINS, BIOMATERIALS AND ENERGY STORAGE APPLICATIONS

   Ike, Sandra N (May 2025, Penn State University)

   Interest in graphitizing hard carbons has peeked in recent years due to the applications of graphitic carbon in energy storage applications and the need to transition to greener energy and transportation. Hard carbons have initially been graphitized with the use of metal catalysts but a downside to this method is the occurrence of metal impurities in the resultant graphitic carbon which then makes it detrimental to applications. Moreover, the process of purification could also be costly. This dissertation aims to present a novel technique—templating using 2-dimensional (2D) nanomaterials—to graphitize model hard carbons. The scope of this dissertation answers the following: ❖ Does carbonization pressure affect the graphitization of soft and hard carbons? ❖ Are the characteristics/properties of 2D nanomaterials effective in templating and aiding graphitization of model hard carbons? ❖ What mechanisms are operative during templating graphitization and what are their contributions? ❖ How do the properties of the modified hard carbons influence their performance in energy storage applications? To address the aforementioned questions, in-depth studies, and novel processes were employed. The first part of this thesis explores the role of carbonization pressure in the graphitization of model soft and hard carbons. The model soft and hard carbons were subjected to carbonization under autogenic and atmospheric pressure conditions and their graphitic evolution at different high temperatures treatments was characterized. Next, the thesis explores the effect of 2D nanomaterials in the form of graphene oxide and its derivatives in inducing the graphitization of phenolic resin, novolac. Two mechanisms were identified (physical and chemical templating) as operative in aiding the graphitization of the novolac matrix. The thesis further explores the templating technique on the graphitization of a biomaterial, lignin, where methods were employed to improve the interactions between the lignin matrix and the graphene oxide additives. The results from the above-described work in the phenolic resin and biomaterial prompted the need for an in-depth understanding of the templating mechanisms and their contributing factor to graphitization. In this regard, the thesis then scrutinizes the predominant force and operative mechanism driving graphitization— physical templating versus chemical templating. Finally, the thesis assesses the influence of the properties of modified hard carbons in energy storage applications and provides strategies for performance improvement. Collectively, the important contribution of this thesis is centered on the development of 2D nanomaterial templating in inducing graphitization of hard carbons (which requires no purification process for the resultant graphitic carbon), understanding the templating mechanisms interplay in modifying and tailoring crystalline properties in hard carbons and lastly, highlighting the electrochemical performance of the modified hard carbons in energy storage applications. 

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5. INVESTIGATING STRESS TRANSFER AND FAILURE MECHANISMS IN GRAPHENE OXIDE-CELLULOSE NANOCRYSTALS FILMS

   https://doi.org/10.12783/asc36/35862  

   JAYATILAKA, GEHAN; MOHAMMADI, MOHAMMAD MOEIN; TEHRANI, MEHRAN (September 2021, PROCEEDINGS OF THE AMERICAN SOCIETY FOR COMPOSITES—THIRTY-SIXTH TECHNICAL CONFERENCE ON COMPOSITE MATERIALS)

   Graphene oxide (GO) films have great potential for aerospace, electronics, and renewable energy applications. GO sheets are low-cost and water-soluble and retain some of Graphene’s exceptional properties once reduced. GO or reduced GO (rGO) sheets within a film interact with each other via secondary bonds and cross-linkers. These interfacial interactions include non-covalent bonds such as hydrogen bonding, ionic bonding, and π-π stacking. Stress transfer and failure mechanisms in GO and rGO films, specifically how linkers affect them, are not well understood. The present study investigates the influence of inter-particle interactions and film structures, focusing on hydrogen bonds introduced via cellulose nanocrystals (CNC), on failure and stress-transfer of the GO and rGO films. To this end, GO films with CNC crosslinkers were made, followed by a chemical reduction. The few-micron thick films were characterized using tensile testing. All tested films exhibited a brittle failure and achieved tensile strengths and modulus in the ~40-85 MPa and ~3.5-9 GPa ranges, respectively. To reveal stress transfer mechanisms in each sample, tensile in-situ Raman spectroscopy testing was carried out. By monitoring the changes in bandwidth and position of Raman bands while stretching the film, useful information such as sheet slippage and cross-linker interactions were gathered. The addition of CNC enhanced modulus but degraded strength for both GO and rGO films. Interestingly, the Raman G-peak shift at failure, indicative of stress transfer to individual GO/rGO particles, is commensurate with the films’ strengths. Correlating these results with the structure and composition of different films reveals new understanding of stress transfer between GO/rGO particles, paving the way for the scalable manufacturing of strong and stiff GO-based films. 

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