The crystal plane effect of CoFe nanocrystals on Fischer–Tropsch synthesis

Abstract

Both CoFe nanowires and nanosheets with preferentially exposed distinguished crystal planes have been fabricated to investigate the crystal plane sensitivity in catalysis. CoFe nanowires and nanosheets are obtained by a stepwise topotactic transformation involving the hydrothermal treatment and thermal decomposition of the iron-doped cobalt carbonate hydroxide hydrate intermediate on an iron substrate, and subsequent reduction of cobalt iron oxides. The CoFe nanowires and nanosheets show different catalytic activities for Fischer–Tropsch synthesis. The CO conversion is 44% over nanowires and 13% over nanosheets at 300 °C, with the corresponding mass specific rates of CO consumption being 10.18 and 2.98 μmol g⁻¹ s⁻¹, respectively. The excellent performance of nanowires is ascribed to the large fraction of active (110) crystal planes. The TOF of the Co atom on {110} crystal planes is 8.2 × 10⁻² s⁻¹ at 300 °C, which is 2.6 times higher than that on {11} crystal planes.