Multilayer graphene in situ formed in carbonized waste paper with the synergism of nickel and sodium

Abstract

Multilayer graphene (MLG) is in situ formed in a matrix of amorphous carbon prepared from carbonized waste paper at 750 °C. The resulting samples are systematically characterized by morphology, spectroscopy, diffractometry, nitrogen adsorption–desorption and electrochemistry. The carbon structure with six layered graphene can be formed in a matrix of amorphous carbon at such a low temperature. The resulting sample displays a specific surface area of 862 m² g⁻¹, a meso-pore volume of 0.55 cm³ g⁻¹ and a capacitance of 214 F g⁻¹, which are correspondingly 2.16, 2.29 and 2.14 times higher than those of the sample prepared directly from carbonized waste paper. Although the sample displays the basic characteristics of amorphous carbon, MLG is mostly found to be formed around the regular nickel crystal face in the amorphous carbon matrix. It is also found that the formation of MLG can be affected by the coexistence of nickel crystals and sodium metal. The optimized porous structural characteristics, including the specific surface area, and the micro- and meso-pore volumes, result from the rearrangement of graphite microcrystallites, giving an improved capacitive performance.