The transformation of acetylene black into onion-like hollow carbon nanoparticles at 1000 °C using an iron catalyst

Acetylene carbon blacks were heat treated at 1000 °C in the presence of ferric nitrate. The morphologies and structural features of original carbon blacks and the carbonized product were investigated using TEM, HRTEM, XRD and nitrogen sorption measurements. It was found that, with the increase of ferric nitrate loading from 4:1, 8:1, 12:1 to 16:1 (the weight ratio of ferric nitrate to acetylene carbon black), the yield of carbonized product decreased from 64.6%, 61.8%, 46.2% to 28.6%. Onion-like hollow carbon nanoparticles with diameter of 40 to 100 nm were generated, implying that the discontinuous short fragments of carbon black were reconstructed and transformed into turbostratic concentric graphitic layers by the iron-based catalytic graphitization. The mechanism was discussed briefly.