EDA/PANI derived FeNxC with Fe-Nx active sites as room temperature hydrogen storage material

Abstract

FeNxC is explored as an efficient and cost-effective hydrogen storage material. Fe/Ethylenediamine (EDA) complex formed initially is protected by (Polyaniline) PANI polymer that gets converted to FeNxC through two-step pyrolysis process. In the first pyrolysis, (Iron sulfide) FeS particles are formed, which get converted to Fe3O4 nanoparticles in second pyrolysis. Fe-Nx active sites get exposed in micro/mesoporous carbon matrix after oxide removal through acid wash. Hydrogen adsorption studies are conducted at 25–100 °C temperature, 5–30 bar pressure. The maximum hydrogen storage capacity is observed as 2.83 wt% at 26 bar, 25 °C for the two-step calcined, acid-washed FeNxC-900–800 A, which possesses large surface area of 995 m2/g, pore volume of 0.711 cm3/g when compared to FeNxC-900–800 and FeNxC-900. The adsorption mechanism, spillover occurring at covalently bonded Fe-Nx active sites and subsequent migration, diffusion to get physisorbed within porous carbon surface, leads to the enhancement in the hydrogen adsorption.