Synthesis and Characterization of a Nanoporous Carbon CMK-3 modified with Iron for Hydrogen Uptake

JULIANA M. JUÁREZ; MARCOS B. GÓMEZ COSTA; OSCAR A. ANUNZIATA

Estocolmo

Congreso; European Advanced Materials Congress; 2017

AMC

The aim of this work is to synthesize a nanostructured Carbon CMK-3 modified with Fe in order to increase its capacity in hydrogen storage. The approach that we have followed includes synthesis of nanostructures with the experimental study of its adsorption capacity and storage properties. Ordered mesoporous carbon CMK-3 was synthesized via a two-step impregnation of the SBA-15 silica nanopores with a solution of sucrose using an incipient wetness method. The sucrose?silica composite was heated at 1173 K for 4 h under nitrogen flow. The silica template was dissolved with 5 wt% hydrofluoric acid in order to remove the silica. The template-free carbon product thus obtained was filtered, washed with deionized water and ethanol, and dried. Fe-CMK-3 was prepared by wetness impregnation using FeCl3.6H2O as source of Fe. A solution of FeCl3.6H2O in ethanol was mixed to carbon solution at ambient temperature. The solution was placed in a rotary evaporator to remove excess of ethanol at about 333K and 60 rpm. Afterwards, the sample was dried at 373K for 18 h. and was thermally treated in a dynamic inert (N2) atmosphere. The percentage of Fe has been 2 wt% with respect to carbon in the final Fe-CMK-3 material. Porous carbon CMK-3 and the sample modified with Fe were characterized by XRD, FTIR, XPS, BET, TEM and SEM. These studies indicate that it was possible to obtain a CMK-3 replica successfully from SBA-15, using sucrose as a carbon precursor. The surface areas are 1320 m2/g and 1240 m2/g for CMK-3 and Fe-CMK-3, respectively. While the nanomaterial area is significantly smaller with the incorporation of the metal, CMK-3`s characteristic structure is maintained after the metal is within the host, in agreement with the XRD studies. Measurements of hydrogen adsorption at cryogenic temperatures and low pressures were performed. The nanoparticles of Fe incorporated onto the nanostructured carbon CMK-3 showed higher hydrogen uptake at low and high pressures than CMK-3,(4.5 wt% and 2.2 wt% respectively of H2 sorption at 10 bar and 77 K).