Facile Synthesis\nof Uniform Metal Carbide Nanoparticles\nfrom Metal–Organic Frameworks by Laser Metallurgy

Abstract

We report the fast and efficient conversion of metal–organic\nframeworks (MOFs) to phase pure transition-metal carbide (TMC) nanoparticles\nwith uniform size using laser as the energy source, consuming only\n6 W power. Nanoparticles of HfC, ZrC, TiC, V₈C₇, α-MoC, Cr₃C₂, and FeC_<i>x</i> with homogeneous sizes (varied between 6 and 20 nm) were successfully\nproduced, among which HfC and ZrC nanoparticles were obtained, for\nthe first time, with sizes less than 10 nm and in the pure phase.\nThis method was operated directly in air, in stark contrast to traditional\nfurnace heating and laser spray methods, where a protective atmosphere\nis required. The use of MOFs allowed us to precisely tune the composition\nof TMC nanoparticles by dialing in the right type and desirable amounts\nof organic linkers. FeC_<i>x</i> nanoparticles\ndoped with various percentages of nitrogen atoms were synthesized\nfor the Fischer–Tropsch reaction without any pretreatment or\nactivation. Extremely high iron time of yield (FTY) values were observed,\n415 and 550 μmol g_Fe^–1 s^–1 (with addition of K), in a 40 h test without any decay in performance.\nA high olefin to paraffin ratio was achieved for C₂ to\nC₁₁ products, where the ratio for C₃ was higher\nthan 10.