Tuning the size and shape of Fe nanoparticles on carbon nanofibers for catalytic ammonia decomposition

[Display omitted] ▶ Fe catalysts were prepared by catalytic CVD growth of CNFs. ▶ Well faceted Fe nanoparticles were obtained on top of the CNFs. ▶ They are highly active and stable for ammonia decomposition to hydrogen. ▶ The activity of Fe particles on platelet CNFs is better than on fishbone CNFs. Fe nanoparticles on the top of carbon nanofibers (CNFs) were synthesized by catalytic CVD on a purpose as catalysts for ammonia decomposition. The size and shape of Fe particles on the top of CNFs depended on the Fe particle reconstruction and CNF morphology. On a mica support Fe catalyst, platelet structure of CNFs was obtained with small, uniform, and unwrapped Fe particles on the top. HRTEM illustrated that the Fe particle surface is covered by a few graphene layers, which redissolves into the Fe particle and does not prevent the access of NH3 to active surface sites at reaction conditions. The catalyst is highly active and stable because the Fe particles are highly dispersed and physically isolated by CNFs, and the surfaces are largely exposed to the reactants.