Synthesis of Ordered Microporous Carbons containing Well-Dispersed Transition Metal Nanoparticles by Direct CVD from Acetylene Gas
Nano-structured carbons containing well-dispersed metal nanoparticles are promising candidates for hydrogen storage and fuel cell applications. Microporous carbons containing well-dispersed transition metal nanoparticles are synthesised in this work.
The following procedure was used to produce the carbons. Powdered zeolite NaY was impregnated with salts containing transition metal ions from metal group VIII, dried overnight. The resulting powder was degassed and loaded into a vertical quartz reactor. Chemical vapor deposition was conducted with acetylene gas (5.18±0.1% in nitrogen gas) for 4 hours at 600°C; further heat-treatment at 900°C was conducted for 3 hours. The inorganic support material was leached from the sample by immersing the composite in 48% hydrofluoric acid, washed with copious purified water and dried in a vacuum oven at 60°C for 24 hours.
TEM images show the produced carbons have templated structure and dispersed metal nanoparticles of sizes ranging from 2nm to 50nm. SEM images show the resulting carbons have well templated zeolite morphology. Nitrogen adsorption measurements show most of the produced carbons possess a high BET surface area and pore volume. DFT reports resolved from the nitrogen isotherm show most of the produced carbons have pore sizes at 7A indicating the replication of the supercage of zeolite Y. Also, pores of size less than 2nm are dominating the produced carbons, which leads to high surface area and micro-pore volume. X-ray diffraction and TGA results show metal loading rates range from 3% to 40%. These materials are promising candidates for fuel cell or hydrogen storage applications.