Ultra-low-cost route to mesocellular siliceous foam from steel slag and mesocellular carbon foam as catalyst support in fuel cell

Abstract

A large- and uniform-pore-sized mesocellular siliceous foam with a high surface area is successfully synthesized, using blast-furnace slag as an ultra-low-cost silica source, under neutral pH conditions. A high-purity silica source can be easily prepared from blast-furnace slag by extraction using an acid leaching process, followed by dissolution in NaOH solution. The mesocellular siliceous foam is synthesized by the interaction of these silicate precursors with P123 ((EO) 20(PO) 70(EO) 20) block copolymers in the presence of trimethylbenzene (TMB) used as a pore expander, followed by calcination at 550 °C in air. The resulting mesocellular siliceous foam denoted as MSU-F–SP has ∼30 nm sized large pores and high BET surface area of 554 m 2 g −1. The structure of MSU-F–SP is very similar to MSU-F silica synthesized from sodium silicate mixtures in the presence of P123 and TMB. Mesocellular carbon foam is easily synthesized through the direct carbonization of a tri-block copolymer in the as-synthesized mesostructured materials after acid-catalyzed polymerization using sulfuric acid. The sulfuric acid is used as a dehydration catalyst and the amount of sulfuric acid is controlled to optimize the pore structure. The mesocellular carbon foam synthesized using 0.16 mL of sulfuric acid per gram of composite material has the most uniform pore structures. A mesocellular carbon foam with high surface area and large mesopores allows good dispersion of Pt nanoparticles, leading to a higher methanol electro-oxidation activity in fuel cells compared to that of Pt nanoparticles on Vulcan XC-72.