Hydrogen as the key factor controlling the efficiency of carbon nanofibers synthesis from ethylene

[Display omitted] •Hydrogen-assisted CCVD of ethylene over a bulk Ni-Cu alloy was studied.•The highest carbon yield was achieved in the hydrogen content range of 40–70 vol%•As found, the hydrogen supply is required throughout the process.•The presence of hydrogen prevents deactivation of the catalytic particles.•Both the structural and textural characteristics of CNFs are affected by hydrogen. Carbon nanofibers with specified textural characteristics, obtained via catalytic chemical vapor deposition of various hydrocarbons, attract growing interest from both scientists and industrialists. In the present work, the optimal hydrogen content in terms of the carbon accumulation rate, process selectivity, and productivity of the Ni-Cu catalyst was found to be in the range of 40–70 vol%. As was revealed by the X-ray diffraction analysis, the catalytic particles are represented by a solid Ni-Cu solution based on the fcc lattice of Ni, and their composition does not depend on the hydrogen concentration. As found, the introduction of an optimal hydrogen amount into the initial reaction mixture decreases AD/AG (from 2.59 to 2.43) and increases both specific surface area (from 127 to 165 m2/g) and total pore volume (from 0.15 to 0.26 cm3/g). Thus, the effect of hydrogen on the decomposition of ethylene over self-dispersing catalysts is studied for the first time.