Temperature effects on formation of carbon-based nanomaterials from kraft lignin

The formation of carbon-based nanomaterials was investigated through heating iron nitrate promoted kraft lignin at different temperatures up to 600 °C under argon gas at atmospheric pressure. High-resolution transmission electron microscopy and electron diffraction images showed that multi-layer turbostratic-structured graphene presented in samples heated at 600 °C. X-ray diffraction results indicated that iron oxides nanoparticles started their formation as an amorphous carbon matrix at 300 °C, and turned into α-Fe nanoparticles at 600 °C. It is believed that the formation of observed multi-layer graphene materials is based on the dissolution and precipitation mechanism of carbonaceous gases from lignin decomposition acting as carbon sources and α-Fe working as the catalyst.