An analysis of microstructural variations in carbon black modified by oxidation or ultrasound

The microstructure and electronic structure of modified carbon black (CB) were investigated by Raman spectroscopy, transmission electron microscopy, electron energy loss spectroscopy and ultraviolet spectroscopy. The modified CB samples include oxidised CB and ultrasound-treated CB under different modification conditions. Typical parameters, such as graphene layer size, the ratio of sp2/sp3-hybridised carbon atoms, energy gap (Eg), and π–π∗ band position, provide information on the microstructure and electronic structure, and these parameters also allow discrimination between different modified CB samples to achieve a desired structure. Oxidation conditions could be carefully chosen to prevent excessive corrosion and form an ordered structure. However, ultrasound has a reverse effect; the graphite layers of the CB samples were exfoliated, and a disordered microstructure was visible. The results indicate that increasing sp2-island size in CB samples decreases the optical gap and increases ultraviolet absorption.