Facile synthesis of high-surface-area nanoporous carbon from biomass resources and its application in supercapacitors.

Yuechao Yao,Qi Zhang,Shao-Zhong Zeng,Xierong Zeng,Lin Huang,Jizhao Zou,Liang Yu,Peng Liu,Lijia Liu

doi:10.1039/c7ra12525a

Abstract

It is critical for nanoporous carbons to have a large surface area, and low cost and be readily available for challenging energy and environmental issues. The pursuit of all three characteristics, particularly large surface area, is a formidable challenge because traditional methods to produce porous carbon materials with a high surface area are complicated and expensive, frequently resulting in pollution (commonly from the activation process). Here we report a facile method to synthesize nanoporous carbon materials with a high surface area of up to 1234 m2 g−1 and an average pore diameter of 0.88 nm through a simple carbonization procedure with carefully selected carbon precursors (biomass material) and carbonization conditions. It is the high surface area that leads to a high capacitance (up to 213 F g−1 at 0.1 A g−1) and a stable cycle performance (6.6% loss over 12 000 cycles) as shown in a three-electrode cell. Furthermore, the high capacitance (107 F g−1 at 0.1 A g−1) can be obtained in a supercapacitor device. This facile approach may open a door for the preparation of high surface area porous carbons for energy storage.

Highlights

IntroductionMany strategies have been reported to obtain nanoporous carbon (NPC) with high speci c surface area (SSA), including carbonization of high SSAs metal–organic frameworks (MOFs),[20,21] physical chemical activation,[10,22,23,24,25,26] and nanocasting strategy with hard templates[27] (for example, nanoporous silica)
Supercapacitors have been used in energy storage devices and have been a hot research area, due to their long cycle life and high power density.[1,2,3] Supercapacitors can be divided into electrical double layer capacitors (EDLC) and Faraday capacitors
Field emission scanning electron microscopy (FESEM) images were captured by a Hitachi SU-70 FESEM instrument, and transmission electron microscopy (TEM) was conducted via a JEOL 2011 TEM facility

Summary

Introduction

Many strategies have been reported to obtain nanoporous carbon (NPC) with high SSAs, including carbonization of high SSAs metal–organic frameworks (MOFs),[20,21] physical chemical activation,[10,22,23,24,25,26] and nanocasting strategy with hard templates[27] (for example, nanoporous silica). NPC of high SSAs was obtained by above these methods, their processes of production were very complicated and costly. A series of high SSA NPC materials have been obtained from renewable biomass resources through pyrolysis. (a) Fabrication of conventional NPC by carbonization method This method usually includes process of pre-treatment or activation. A facile method of calcining renewable biomass resources to obtain high SSA NPC materials is highly desired. We reported a facile and cost-effective method to produce NPC materials with high SSA by carbonizing heart wood of Root of Multibract Raspberry (ROMR explanation, S1†). Compared to the other processes for pre-treatment or activation step (Scheme 1a), the high SSA (1234 m2 gÀ1) was obtained by the direct carbonization of precursor at 900 C in our process as shown in Scheme 1b. The results showed a high capacitance (up to 213 F gÀ1 at 0.1 A gÀ1) and a stable cycle performance (6.6% loss over 12 000 cycles) in a three-electrode cell

Materials characterization

Synthesis of NPC

The fabrication of supercapacitor electrode and electrochemical measurements

Results and discussion

Conclusion