Simultaneous activation and N-doping of hydrothermal carbons by NaNH2: An effective approach to CO2 adsorbents

Synthesis of carbon materials with both large surface area and abundant heteroatoms is an important task in scientific research. Traditional approaches mostly proceed at extremely high temperature, and suffer from complex routes and/or expensive raw materials. NaNH2 has been recently found to be able to not only etch C atoms to create nanochannels, but also substitute O species to introduce N species. In this work, an effective approach to N-doped porous carbons was realized by treating hydrothermal carbons (HTCs) with sodium amide (NaNH2). The considerable amount of O species preserved in pristine HTCs enables the achievement in simultaneous activation and N-doping of HTCs by NaNH2 at relatively moderate temperature (400(similar to)600 degrees C). The porous and chemical structure of NaNH2-treated HTCs were characterized systematically. Although the pristine HTCs are almost non-porous and N-free, the specific surface areas and total N contents of prepared NaNH2-treated HTCs reach 190(similar to)2430 m(2)/g and 0.78(similar to)6.57 wt.% respectively. Furthermore, the CO2 capture performance of NaNH2-treated HTCs was also examined considering their highly porous and N-doped nature. Interestingly, NaNH2-treated HTCs exhibit high CO2 capacities, large CO2/N-2 selectivities, fast CO2 adsorption rate and excellent recyclability, endowing them with potential application as solid adsorbents for CO2 capture.