Carbon nanotube/carbon nanofiber growth from industrial by-product gases on low- and high-alloy steels

The growth of carbon nanotubes (CNTs) on sheet metal surfaces (including low- and high-alloyed steel and Ni-plated steel) has been explored using a mixture of CO, CO₂, and H₂ as the precursor feedstock in a thermal chemical vapor deposition process. The influence of various experimental parameters such as the reactor temperature, reaction time, and precursor composition on the yield, purity, and dimensions of the CNTs has been elucidated. Addition of CO₂ during CNT growth leads to higher carbon deposition rates, especially for low- and high-alloyed steel. The diameters of the obtained CNTs range from 12 to 300 nm at carbon deposition rates of ～0.3 mg cm^?2 min^?1. The CNTs are observed to be uniformly distributed and adhered firmly to the substrates. The experimental conditions for CNT growth on sheet metal surfaces are very similar to concentrations and temperatures of a typical effluent stream of the steel industry. This process thus holds potential to harness waste gases to fabricate CNT-based coatings that impart added functionality to sheet metals, while further reducing the carbon footprint of steel plants.