Recycling Waste Rubber Into Single-Walled Carbon Nanotubes: Narrow Chirality Distribution and Hydrogen Byproduct

Abstract

Waste rubber products pose a significant threat to the Earth's ecological environment due to their non-biodegradability and long-term persistence. In this study, we present a method for converting various rubber products into single-walled carbon nanotubes (SWNTs) and hydrogen (H₂) gas via a two-stage chemical vapor deposition (CVD) system. The core of this method is a porous magnesium oxide-supported cobalt catalyst (Co/MgO) prepared via a simple impregnation method, exhibiting high metal dispersion and superior performance. In the pyrolysis stage, thermal decomposition of the rubbers generates various hydrocarbons and carbon oxides. Subsequently, in the catalysis stage, these carbon-containing substances serve as the carbon source for the synthesis of SWNTs on the Co/MgO catalyst, concurrently releasing H₂. Remarkably, under optimal reaction temperatures, the synthesized SWNTs demonstrate a narrow chirality distribution with a (8, 4) SWNT proportion of 20.1%. Moreover, this approach is also applicable to convert real waste tires, which proposes a new avenue to recycling them into high-value carbon nanomaterials and H₂, thus shedding light on mitigating the environmental challenges associated with waste rubber disposal.