Structure of Macroporous Carbon-Carbon Composite Obtained by Deposition of Pyrolytic Carbon on a Carbon Black Matrix

Macroporous carbon materials (macro-PCMs) were obtained using a matrix synthesis approach which consists in the deposition of pyrolytic carbon (PC) on a matrix of P803 carbon black (CB) during its high-temperature treatment in hydrocarbon medium. The microstructure, morphology, and porous structure of synthesized macro-PCMs were studied using a set of methods, such as transmission and scanning electron microscopy, X-ray diffraction, Raman spectroscopy, low-temperature nitrogen adsorption, mercury porosimetry, and helium pycnometry. It was shown that PC is deposited on the CB matrix surface both in the form of ordered graphene layers and as wedge-shaped particles. Two stages of the macro-PCM formation can be distinguished. At the first stage (α < 0.66 g of PC per g of CB), the most accessible macropores with sizes of >100 nm are predominantly filled with PC and then, at the second stage (α > 0.66 g of PC per g of CB), pores with sizes of <100 nm are also filled. A decrease in the specific pore volume V>100 from 0.48 to 0.26 cm3/gCB occurs with volumetric filling of large macropores (>100 nm) between aggregates, while the PC deposition at α > 0.66 g/g leads to a decrease in V<100 to 0.077 cm3/gCB and to an almost constant value for V>100.