Method of synthesizing porous composite including single atom metal catalysts and nitrogen atoms in hierarchical carbon material from carbon dioxide containing gas
The present invention relates to a method of producing a porous composite comprising single-atom metal catalysts and nitrogen atoms by using a hierarchical carbon material from a carbon dioxide-containing gas. According to the present invention, a composite material is produced by producing a porous carbon material using nanosized templates and carbon dioxide, producing carbon nanotubes from the composite material through a self-templating process, and adding single-atom catalysts to the carbon nanofibers. In addition, it is possible to produce a composite having significantly improved porous characteristics and electrochemical properties by nitrogen atom doping using a nitrogen precursor. The produced composite may be easily applied to a high-energy storage device such as a lithium-sulfur battery.
1 . A method of preparing an amorphous hierarchical porous carbon material having micropores (<2 nm) and mesopores (2 to 50 nm), comprising
continuous heat-treating a mixture of a reducing agent and nanotemplates in an inert gas and a carbon dioxide-containing gas at a temperature of 500 to 1,000° C. to obtain a solid product; and
adding a nitrogen precursor to the obtained solid product, followed by heat treatment,
wherein the heat treatment is treated with ammonia gas generated by bubbling an aqueous ammonia solution so that a percentage of nitrogen atoms in the solid product increases from 1-2 at % to 4-7 at %, and a content of nitrogen atoms in the solid product increases from 0.5-2.0 wt % to 3.0-6.0 wt %.
2 . The method of preparing an amorphous hierarchical porous carbon material of claim 1 , wherein the reducing agent is at least one selected from the group consisting of magnesium (Mg), magnesium hydride (MgH 2 ), sodium borohydride (NaBH 4 ), potassium borohydride (KBH 4 ), calcium borohydride ((Ca(BH 4 ) 2 ), strontium borohydride (Sr(BH 4 ) 2 ), magnesium borohydride (Mg(BH 4 ) 2 ) and lithium borohydride (LiBH 4 ).
3 . The method of preparing an amorphous hierarchical porous carbon material of claim 1 , wherein the nanotemplates are an alkali metal, alkaline earth metal or transition metal oxide or carbonate.
4 . The method of preparing an amorphous hierarchical porous carbon material of claim 1 , wherein the bubbling an aqueous ammonia solution is performed with an inert carrier gas at a temperature of 500 to 1,000° C.