Synthesis of highly porous N-doped hollow carbon nanospheres with a combined soft template-chemical activation method for CO2 capture

Abstract

In the present study, N-doped hollow carbon nanospheres (NHCNs) were synthesized with a combined soft template-chemical activation method. Spherical hollow hydrochar was prepared from glucose with the assistance of dual soft templates, and was then chemically activated with KHCO3 and urea to produce the NHCNs. Effects of urea addition and activation temperature on the NHCNs’ physicochemical properties were revealed. The NHCNs were endowed with rich N-doping and developed porosity. The sample activated at 800 °C (NHCN2800) showed an impressive specific surface area of 3234 m2/g. The proposed method could also be extended to the synthesis of N, S co-doped hollow carbon nanospheres. We then investigated CO2 adsorption performances of the NHCNs. At 25 °C and 1 bar, the best CO2 uptake of the NHCNs was 4.36 mmol/g; at 20 bar, it increased to a record high level of 23.62 mmol/g. Correlations between textural characteristics/N-doping and CO2 adsorption at 1/20 bar were analyzed and discussed. The current study indicated that the obtained NHCNs had great potential for applications in both pre- and post-combustion CO2 capture.