Non-destructive and controllable catalyst deposition of in situ growing carbon nanotubes onto the carbon fibre fabric

To in situ grow carbon nanotubes (CNTs) on the surface of carbon fibre fabric (CFF) with suitable diameter and uniform distribution, controllable catalyst deposition is the key process. A controllable and non-destructive pre-treatment, that is, electrochemical oxidation pre-treatment, was explored to facilitate uniform `seeding` nano-sized catalyst particles on the surface of CFF without causing damage to carbon fibres. Main factors, such as voltage, concentration of electrolyte, electrolytic time, catalyst type and concentration of the catalyst precursor, were investigated. X-ray photoelectron spectroscopy tests indicated that voltage, concentration of electrolyte and duration of electrochemical treatment determined the distribution density of catalyst nanoparticles by controlling the concentration of the functional groups, while the diameter of catalyst particles was decided by the concentration of Fe(NO₃)₃ and CO(NH₂)₂. Besides, the diameter of catalyst particles could be modulated by adding Al(NO₃)₃ in the solution of the catalyst precursor. At the same time, to avoid cementite produced during the calcination and reduction process, the temperature should be controlled below 773 K. Scanning electron microscopy observations indicated that well-dispersed in situ grown CNTs could be obtained after CFF had been chemical oxidised at the voltage of 10 V for 10 s with 0.02 M NH₄HCO₃ as electrolyte and followed by catalyst deposition.