CVD synthesis of solid, hollow, and nitrogen-doped hollow carbon spheres from polypropylene waste materials

Abstract

Plastic waste leaves a serious environmental footprint on the planet and it is imperative to reduce this. Consequently, recycling has been regarded as an important approach in providing one solution to this problem. In this study, we enhanced the value of polypropylene (PP) plastic waste by using it as a hydrocarbon source to synthesize a variety of spherical carbon nanomaterials. Here, a CVD method was used to decompose the PP initially into a hydrocarbon gas (propylene). Thereafter, PP was employed to synthesize solid carbon spheres (SCSs), hollow carbon spheres (HCSs), and nitrogen-doped hollow carbon spheres (NHCSs). The latter two were made using a silica template while the N-doping was achieved by the addition of melamine to PP. Yields obtained were between 12-20%. The SCSs (d = 800 nm to 1200 nm), HCSs (id = 985 nm; shell width = 35 nm), and NHCSs (id = ca. 1000 nm; shell width = 40 nm) were all characterized by TEM, SEM, TGA, laser Raman spectroscopy, and XPS.