Controlled Synthesis of Ordered Mesoporous Carbon-Cobalt Oxide Nanocomposites with Large Mesopores and Graphitic Walls

Abstract

Ordered mesoporous carbon (OMC)-metal oxide composites have attracted great interest due to their combination of high surface area, uniform pores, good conductivity of mesoporous carbon, and excellent photo-, electro- and chemical sensing properties of metal oxides. Herein, OMC-metal oxide composites with large mesopores and monodispersed CoO_<i>x</i> nanoparticles were synthesized via a controllable multicomponent cooperative coassembly of ultrahigh-molecular-weight poly­(ethylene oxide)-<i>block</i>-polystyrene (PEO-<i>b</i>-PS) copolymers, resol (soluble phenoic resin carbon precursor), and cobalt nitrate (cobalt oxide precursor). The obtained nanocomposites possess a face-centered cubic (fcc) mesoporous structure, large pore size (13.4–16.0 nm), high surface area (394–483 m²/g), large pore volume (0.41–0.48 cm³/g), and uniform CoO_<i>x</i> nanoparticles with tunable diameters (6.4–16.7 nm). The long chain length of amphiphilic PEO-<i>b</i>-PS template molecules contributes to large mesopores and thick pore walls that allow a controllable nucleation of metal oxides and the formation of CoO_<i>x</i> nanoparticles that are partially embedded and stabilized in the graphitic carbon walls and semiexposed in the mesopore channels, avoiding pore blockage and facilitating the mass transportation of guest molecules. The <i>in situ</i> loaded highly dispersed CoO_<i>x</i> nanoparticles promote the graphitization of carbon frameworks during the pyrolysis procedure at relative lower temperatures (∼700 °C). Due to the strong synergistic effect between the graphitic OMC with large pores and uniform active p-type CoO_<i>x</i> nanoparticles, the obtained mesoporous nanocomposite exhibit superior performance in hydrogen sensing