In Situ Production ofNi Catalysts at the Tips ofCarbon Nanofibers and Application in Catalytic Ammonia Decomposition.

Ni-carbon nanofibers (Ni-CNFs) catalysts were synthesizedin situby the decomposition of carbon-containing gases (i.e., CH4, CO, and C2H4) over Ni/Al2O3catalyst and directly used to catalyze ammonia decomposition.The results showed that Ni nanoparticles were found to locate at thetips of CNFs when using CH4and CO as carbon sources, whilethey located at the roots of CNFs when using C2H4as a carbon source. For ammonia decomposition, Ni catalysts at thetips of CNFs showed higher activity, which could be due to the moreaccessible surfaces to the reactants. Interestingly, the Ni catalystat the tips of CNFs with CH4as a carbon source exhibitedhigher activity than that with CO as a carbon source, even thoughthe former catalyst had a larger average particle size. The possiblemechanism was given by combining characterization results with ourprevious simulation results. Finally, when using CH4asa carbon source, the effect of the Ni-CNFs catalysts with differentgrowth times on the activity was further studied. [ABSTRACT FROM AUTHOR]