Self-assembly of polyhedral oligosilsesquioxane (POSS) into hierarchically ordered mesoporous carbons with uniform microporosity and nitrogen-doping for high performance supercapacitors

Polyhedral oligosilsesquioxanes (POSS), regarded as the smallest possible particles of silica, are used as carbon source and assembled into hierarchically porous carbon structures by a block copolymer-assisted method. The obtained carbon materials with high specific surface area of over 2000 m(2) g(-1) and large pore volume of over 1.19 cm(3) g(-1) possess both quite uniform micropores with the size of similar to 1 nm and highly ordered mesopores with the size of similar to 4 nm, owing to the molecular-scale templating effect of POSS siloxane cages as well as the good assembly compatibility between the block copolymers and the aminophenyl-functionalized POSS used. The mesopore arrangement can be two-dimensionally hexagonal (p6m) or body-centered cubic (Im (3) over barm) by simply adjusting different block copolymers. Nitrogen functionalities with a relatively high content (similar to 4 wt%) can spontaneously be incorporated into those carbon materials. Benifiting from the uniform microporosity and the nitrogen doping, the specific capacitance of the POSS-derived hierarchically porous carbons can reach similar to 160 F g(-1) in ionic liquid electrolyte and similar to 210 F g(-1) in 1 M H2SO4 aqueous electrolyte, when measured at a current density of 0.25 A g(-1) in a symmetrical two-electrode cell. More importantly, the highly ordered mesopores can facilitate ions fast transportion to the fine micropores to achieve the excellent power performance. The hierarchial carbon sample with a hexagonal mesostructure and a high mesoporosity displays the best rate capability with 94% and 97% of capacitance retention in ionic liquid and 1 M H2SO4, respectively, with the current density range from 0.25 to 10 A g(-1). By combining self-assembly strategy with rich POSS chemistry, we believe that many other hierarchical hybrid materials or carbon materials with unique electrochemical properties can be synthesized. (C) 2016 Elsevier Ltd. All rights reserved.