Investigation of the parameters of carbon nanotube growth on zirconium diboride supported Ni catalyst via CVD

Carbon nanotubes (CNTs) were synthesized on zirconium diboride (ZrB2) through CVD using a Ni catalyst. The influences of the synthesis temperature, time and catalyst amount on the quality and quantity of grown CNTs were studied. The catalyst content determined the temperature at which the CNTs began to grow. When the Ni catalyst content was low, the temperature at which the CNTs began to grow should be higher, and was 1050 degrees C for 5 wt% Ni content, but was 950 degrees C for 15 wt% Ni content. Meanwhile, agglomeration of metal atoms was observed if the synthesis temperature was increased until reaching the upper limit temperature for CNT synthesis, which was 1100 degrees C for 5 wt% and 10 wt% Ni content, but was 1000 degrees C for 15 wt% Ni content. Increased Ni catalyst content also led to higher catalytic activity as long as the Ni catalyst content did not exceed 15 wt%. Meanwhile, prolonged synthesis time extended the reaction time for the decomposition of C2H2, but resulted in the agglomeration of carbon atoms when the synthesis time was 150 min. The results showed that the uniform distribution of CNTs can be obtained in ZrB2 powder and there was no reaction between ZrB2 and Ni catalyst. The suitable synthesis conditions for obtained uniform size of CNTs grown with a higher degree of graphitization on ZrB2 that identified in this work were: Ni catalyst content of 10 wt%, synthesis temperature of 1050 degrees C, and synthesis time of 120 min.