Hierarchically structured carbon replica of hybrid layered double hydroxide

Abstract

A hierarchically structured carbon replica with a tri-modal distribution of porosity was prepared by pyrolysis of a three-dimensionally ordered macroporous (3-DOM) organic–inorganic hybrid layered double hydroxide (LDH). By an original inverse opal method involving LDH platelet regeneration, macroporous Mg₂Al–vinyl benzene sulfonate (VBS) was synthesized and subsequently submitted to a moderate thermal treatment to induce the VBS in situpolymerization. Successive steps of carbonization and demineralization were conducted to yield to a carbon replica. A thermal treatment under inert atmosphere ensures the carbonization of the organic part and the simultaneous decomposition of the LDH into oxide and mixed oxide particles. The latter acts as a porogen agent during the acid-leaching step, which induces the removal of the inorganic part. The samples upon carbonization and the capacitive properties of the resulting carbon replica were thoroughly characterized using powder X-ray diffraction (PXRD), Fourier-transform infra-red (FTIR) and ¹³C nuclear magnetic resonance (NMR) spectroscopy, field-emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM) and Brunauer–Emmet–Teller (BET) analysis of the nitrogen adsorption isotherm. 3-DOM carbon replicas exhibit poor capacitive behaviour in aqueous electrolyte, explained by a high ionic resistivity present in the porosity. Even though this electrical disruptive effect can be explained on the basis of the macroporosity of the disconnected carbon 3-DOM, this allows us to envisage other applications for this approach in order to obtain tri-modal carbon-based materials.