Morphology Tuning for Hard Carbon Nanomaterials by Manipulation of PTCDA Volatilization in the Chemical Vapor Deposition Process

A facile and low-cost synthesis method for carbon nanomaterials using an organic molecule perylene tetracarboxylic dianhydride (PTCDA) as a precursor is presented. The resulting products exhibit a combination of floccular and fibrous morphologies, along with a low-crystallinity graphitic nanostructure characteristic of hard carbon. The synthesis is carried out by using a low-pressure chemical vapor deposition (CVD) system, during which the pressure changes in the CVD chamber are continuously monitored. These pressure variations provide critical insights into the material transformations at specific temperatures. A range of characterization techniques are employed to elucidate the structural and chemical changes occurring at temperatures corresponding to the pressure shifts. It is demonstrated that the disruption of PTCDA crystallinity promoted by amorphous PTCDA volatilization at relatively low temperatures (≤450 °C) is important for the formation of floccular and fibrous nanomaterials with an enlarged specific surface area reaching 359 m² g^-1 and hierarchical porous structures. Consequently, controlling the volatilization and crystallinity of PTCDA is essential to tuning the structures of the produced nanomaterials. This study presents a novel template-free approach for the controllable synthesis of hard carbon materials, demonstrating that the investigation of the material formation process and mechanism is significant for optimizing the preparation of hard carbon materials with diverse morphologies and nanostructures.