Progress in-situ synthesis of graphitic carbon nanoparticles with physical vapour deposition

Graphitic carbon nanoparticles are in high demand for sensing, health care, and manufacturing industries. Physical vapour deposition (PVD) methods are advantageous for in-situ synthesis of graphitic carbon particles due to their ability to produce large area distributions. However, the carbon particles can agglomerate, irrespective of the PVD method, and form coagulated structures while growing inside the vacuum chamber. The random shapes and sizes of these particles lead to non-uniform properties and characteristics, hence making them less attractive for numerous industrial applications, such as energy storage batteries and structural health monitoring. Therefore, the in-situ synthesis of isolated carbon particles produced in a single-step PVD process having control over size, shape, and large area distributions has remained inspiring for the past 30 years. This article gives an overview of characteristics, applications, industrial impact, and global revenue of graphite particles. A critical review on in-situ growth of graphitic carbon particles with different PVD methods is described with selected examples. A comprehensive summary compares the capability of different PVD techniques and corresponding carbon resources to produce graphitic particles with numerous sizes and shapes. Analysing the outputs of various PVD methods, a generalised four-stage model is explained to understand the in-situ growth of graphitic carbon particles, which start from seedings and grow as particles, clusters, and granular structures. It is concluded that the isolated carbon particles can be produced with specific size, shape, and distributions irrespective of the PVD method employed, by maintaining precise control over combinations of deposition system properties and process parameters.