Rapid synthesis of carbon nanoparticles with an optimized combination of specific surface area and crystallinity by a plasma-assisted single-step process

Plasma-assisted synthesis of carbon encapsulated magnetic nanoparticles with controlled sizes correlated to smooth variation of magnetic properties

“…This is yet another reason why more oxygen reactivity was seen in samples synthesized at lower pressure, which we know from our previous experiments produces inferior graphitization of the material. We had demonstrated before that inter atomic distances (d 002 ) of carbon layers as measured by XRD may be used as a fine index to quantify the extent of graphitization of the synthesized materials [29]. XRD of the low pressure synthesized samples in this present experiment shows two different carbon peaks close to each other ( Figure 3, inset (d)), [29].…”

“…We had demonstrated before that inter atomic distances (d 002 ) of carbon layers as measured by XRD may be used as a fine index to quantify the extent of graphitization of the synthesized materials [29]. XRD of the low pressure synthesized samples in this present experiment shows two different carbon peaks close to each other ( Figure 3, inset (d)), [29]. This ensured that the present product, even at 20 mbar pressure, was well-graphitized, whereas in conventional plasma assisted ϭϮ systems, the material often turns out to be highly amorphous even at few hundred millibar pressure [32].…”

“…In Figure 10(c), BJH adsorption dV/dD pore volume is plotted against pore diameter for the samples, which shows that the low pressure samples with higher specific surface area has higher volume contributed by the mesopores. Mesopores in carbon supports usually lead to higher specific surface area, enhanced diffusion of chemical species and preferential adsorption of large molecules [29].…”

“…We have developed a thermal plasma assisted experimental nanoparticle reactor configuration for synthesis of different high temperature nanomaterials, where precursors embedded in the jet undergo uniform, rapid cooling while expanding into a low pressure sample collection chamber, which ensures narrow size distribution of the product particles [25][26][27][28][29]. A unique feature of this experimental reactor is that the plasma production zone remains isolated from the particle nucleation/growth zone through a supersonic nozzle, allowing variation of pressure in the sample collection chamber over a wide range down to the few mbar level, which may be used as an efficient control knob for tuning the average particle size and size distribution [27][28][29].…”

“…A unique feature of this experimental reactor is that the plasma production zone remains isolated from the particle nucleation/growth zone through a supersonic nozzle, allowing variation of pressure in the sample collection chamber over a wide range down to the few mbar level, which may be used as an efficient control knob for tuning the average particle size and size distribution [27][28][29]. The present experiment aims at synthesizing carbon stabilized iron nanostructures by this plasma expansion technique and thus combine the conventional advantages of thermal plasmas with better size control as likely to be offered by this particular technique.…”