Ultra-small carbon nanospheres (< 50 nm) of uniform tunable sizes by a convenient catalytic emulsion polymerization strategy: superior supercapacitive and sorption performances

Abstract

Porous carbon nanospheres have received enormous attention for various applications. Though there are several elegant strategies existing for the synthesis of relatively large carbon nanospheres (> ca. 100 nm), the synthesis of carbon nanospheres with well-defined tunable ultra-small sizes (< 50 nm) has often been challenging while such ultra-small nanospheres are much more valuable. A novel, convenient, and scalable catalytic emulsion polymerization technique is demonstrated in this paper for highly efficient synthesis of ultra-small carbon nanospheres with uniform tunable sizes in the range of 11–38 nm. In this strategy, a simple change of the emulsion polymerization recipe renders a convenient yet efficient tuning of the size of the carbon nanospheres. In particular, activated carbon nanospheres (A-CNS21 of average size of 21 nm) obtained by carbonization in the presence of KOH as the chemical activation agent is featured with very high surface area (2,360 m2/g) and the desired hierarchical macro-/meso-/micropore structures resulting from nanosphere packing/aggregation. A-CNS21 is demonstrated to have superior high-rate supercapacitive performances and outstanding sorption capacities towards volatile organic compounds (VOCs), H2, and CO2, which are comparable to or even better than the best results reported to date in these applications. To the best of our knowledge, this is the first synthesis of ultrasmall carbon nanospheres with uniform tunable sizes and superior performances for these applications by the emulsion polymerization strategy.