Nano-CaCO ₃ as template for preparation of disordered large mesoporous carbon with hierarchical porosities

A series of large mesoporous carbons (LMC, 20–50 nm) with hierarchical porosities has been prepared using commercially available CaCO3 nanoparticles as a template, formaldehyde (PF) resin as carbon precursor, and HCl solution for removing the template. During the carbonization process, the CaCO3 template decomposes releasing CO2 which serves as an activating agent to active the carbon materials producing micropores and mesopores as well as enlarging pore sizes. This effect can be named as the “CO2 inner-activation effect”, which is proved by comparing the carbon yield, N2 adsorption/desorption isotherms, pore-size distribution and textual parameters of carbon materials carbonized at two critical temperatures, namely, 900 °C (higher than the pyrolysis temperature of CaCO3) and 650 °C (lower than the pyrolysis temperature of CaCO3). Our results show that the LMC samples prepared at different ratios of CaCO3 to PF have BET surface areas ranging from 503 to 1215 m2 g−1, and pore volumes ranging from 1.8 to 9.0 cm3 g−1. This one-step carbonization method with a CO2 inner-activation effect provides a novel route to prepare large mesoporous carbons and hierarchical porous carbon materials.