Hierarchically Porous Carbon Nanosheets from Waste Coffee Grounds for Supercapacitors

Abstract

The nanostructure design of porous carbon-based electrode materials is key to improving the electrochemical performance of supercapacitors. In this study, hierarchically porous carbon nanosheets (HP-CNSs) were fabricated using waste coffee grounds by in situ carbonization and activation processes using KOH. Despite the simple synthesis process, the HP-CNSs had a high aspect ratio nanostructure (∼20 nm thickness to several micrometers in lateral size), a high specific surface area of 1945.7 m(2) g(-1), numerous heteroatoms, and good electrical transport properties, as well as hierarchically porous characteristics (0.5-10 nm in size). HP-CNS-based supercapacitors showed a specific energy of 35.4 Wh kg(-1) at 11250 W kg(-1) and of 23 Wh kg(-1) for a 3 s charge/discharge current rate corresponding to a specific power of 30000 W kg(-1). Additionally, the HP-CNS supercapacitors demonstrated good cyclic performance over 5000 cycles.

Biocharring of natural fibers of insect and plant origin: a green route for the production of ‘carbon-based charge storage nanomaterials’

“…6e-h. The C1 s spectrum revealed the presence of three types of carbon bonds: C-C/ C=C (284.6 eV) (C-) C-N (285.9 eV), C=C-N (286.5 eV), C=N/C=O (287.9 eV) and O-C=O (289.0 eV), respectively [9,19]. XPS narrow spectrum corresponding to nitrogen (N1 s) in four samples are shown in Fig.…”

“…Further, such biomass derived carbon has been composited with graphene/CNTs and used for constructing supercapacitors and batteries [5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][29][30][31][32][33][34][35][36][37][38][39][40]. Yet a classification of the chemical origin of these biomass is critical for understanding the electrochemical performance of the biocharred carbon.…”

“…Biocharring results in the production of carbon materials of myriad geometries and such geometry and quantity of heteroatom further influences the electrochemical performance. Different biomasses were reported as a precursor for the synthesis of charred carbon for usage in charge storage device [12][13][14][15][16][17][18][19]. Thus, the chemical nature of the biomass greatly influences the structure and the properties of biocharred carbon derived from them.…”

Waste coffee grounds-derived nanoporous carbon nanosheets for supercapacitors

“…3b). The D band at 1353 cm -1 signified a disordered (amorphous) carbon structure, whereas the G band at 1573 cm -1 was indicative of a hexagonal carbon structure [18]. The integral intensity ratios of the D to G bands, I D /I G , were approximately 1.6 and 2.6, for C-WCGs and NCNSs, respectively.…”

Morphologies and surface properties of cellulose-based activated carbon nanoplates

“…The physical and chemical properties of CNMs are highly dependent on their morphologies, components, and microstructural characteristics. Numerous attempts have been made to prepare and characterize 2D CNMs using diverse carbon precursors and synthesis processes [5][6][7][8]. Among the various processes for manufacturing CNMs, pyrolysis of polymeric material has the merits of large scale production, wide availability, and cost effectiveness [9].…”