Development of graphitic and non-graphitic carbons using different grade biopitch sources

Abstract

The growing demand for bio-renewable alternatives to fossil fuels in the production of sustainable carbon materials, aimed at reducing environmental impact, is crucial for advancing a greener future. This research explores an innovative approach for producing biopitches from bio-oils, which are subsequently utilized as a sustainable precursor for developing advanced graphitic carbons (GC) and non-graphitic carbons (NGC) through carbonization and graphitization processes. The study emphasizes the impact of the chemical composition of bio-oils and biopitches, including heteroatom structures, aromatic/aliphatic ratio, and oxygen content with oxygen-bearing functional groups, on the production of GC and NGC. The research also examines their structural parameters at various heating temperatures using characterization techniques such as X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), and Raman spectroscopy. XRD analysis revealed that GC samples have lower interplanar spacing (d₀₀₂) and larger crystallite size than NGC, while Raman shows more short-range order and defects in NGC. Furthermore, HRTEM images and fringe analysis demonstrated differences in lamellae structures, tortuosity, and fringe length. These observations, unveiling differences in crystallite size and degree of graphitization between GC and NGC, underscore the influence of temperature on structural order and defect annealing, which is crucial for optimizing material properties.