Nitrogen/Oxygen Enriched Hierarchical Porous Carbons Derived from Waste Peanut Shells Boosting Performance of Supercapacitors

Abstract

conductivity, abundant morphology, large surface area, and tunable surface properties, porous carbons have been widely used as electrode materials for supercapacitors. [6-9] Various porous carbons have been fabricated from the green precursor of biomass, which exhibits outstanding performance in supercapacitors. Theoretically, the specific capacitance of a supercapacitor depends on the specific surface area of the carbonaceous electrode materials. The larger the surface area, the more the charge accumulated on the interface between the electrode and electrolyte distributions. [2,10,11] Up to now, massive works have been performed to activate the electrode materials to obtain a higher specific surface area. Unfortunately, most of them used some strong corrosive etchants, such as KOH, NaOH, HNO 3 , and H 3 BO 3. [12-25] Recently, Zinc chloride (ZnCl 2) has been widely used to activate the carbon materials to prepare electrode materials with larger specific surface area and proper pore size distribution for high-performance supercapacitors. [24,26-30] It can give higher carbon yield through a dehydrating process allowing more carbon to remain in the structure. [26,27] However, these traditional activation methods can improve the specific surface area of carbon materials at the cost of graphitization. [31] It is known that the electrical conductivity is vital to the electrochemical performance, especially for the rate capability in supercapacitors, which can be improved by increasing the graphitization degree of carbons. [32,33] Cobalt (Co) catalytic graphitization is an effective method to improve the graphitization of carbon materials. Jiang et al. used cobalt nitrate as the graphitization catalyst to synthesize partially graphitized ginkgo-based activated carbons showing a high performance of 178 F g −1 at a scan rate of 500 mV s −1. [32] Chang et al. reported a method of Co 2+ catalyzed graphitization and KOH activation, by which an interconnected nitrogen-doped hierarchical porous carbon with small mesopore size (2-4 nm) and high microporosity (86.8%) was synthesized from the biomass of Firmiana simplex fluff and exhibited an ultrahigh capacitance in supercapacitors. [34] It shows great advantages over the high-temperature treatment with high energy consumption and the related reduction of the surface area. Biomass is a kind of naturally abundant and costeffective precursors to prepare porous carbon materials for The high specific surface area and the fine electrical conductivity are the vital impacts, but they are always a pair of mutually counterbalancing factors in carbon-based supercapacitors. Herein, a facile strategy of the combined CoCl 2 catalytic graphitization and ZnCl 2 activation is applied to synthesize porous carbonaceous materials with enriched nitrogen and oxygen doping from a cheap and abundant biowaste of peanut shells. The as-produced carbon materials possess high surface area (1745-2257 m 2 g −1), naturally nitrogen/ oxygen co-doping, and hierarchical porous structure. These physicochemical p...

Supercapacitors in the Light of Solid Waste and Energy Management: A Review

“…The system acquired a maximum energy density of 42 W h kg −1 and a maximum power density of ≈15 000 W kg −1 with 1-butyl-3 methylimidazolium tetrafluoroborate-acetonitrile (BMIMBF 4 -AN) as the electrolyte. [61] Khan et al used tea waste to derive carbon for supercapacitor electrodes through the three simple steps of precarbonization, acid (1 m HCl solution) washing, and KOH activation. The carbon as obtained had a surface area of 1610 m 2 g −1 .…”

“…The system acquired a maximum energy density of 42 W h kg −1 and a maximum power density of ≈15 000 W kg −1 with 1‐butyl‐3 methylimidazolium tetrafluoroborate‐acetonitrile (BMIMBF 4 ‐AN) as the electrolyte. [ 61 ]…”

“…Therefore, of late, due emphasis has also been laid on the evolution of eco‐friendly supercapacitors. Benign materials retrieved from carbon‐rich agricultural and food biowaste, [ 9,52–75,105,115,116 ] industrial waste, [ 76–79 ] paper, [ 74,80,81 ] and cotton [ 82 ] have been used in their fabrication. Additionally, carbon acquired from discarded polymers [ 83–95 ] as well as valuable metals and metal composites recuperated from electronic waste including spent batteries [ 96–102 ] have been utilized in the preparation of supercapacitor electrodes.…”

Microporous N-Doped Carbon Obtained from Salt Melt Pyrolysis of Chitosan toward Supercapacitor and Oxygen Reduction Catalysts

“…However, the controlled synthesis of chitosan-based porous carbon materials has also been studied through template or activation methods. Specifically, the application of templates such as Zn salts [ 12 , 13 ] Na/K carbonate [ 8 , 9 ], silica [ 14 ], or boric acid [ 15 ]; and activators like KOH [ 16 , 17 ] have resulted in N-doped nanocarbon materials with highly microporous structures possessing gas sorption capability, and electrochemical or electrocatalytic activity [ 18 , 19 ].…”

Carbon Cloth Supported Nitrogen Doped Porous Carbon Wrapped Co Nanoparticles for Effective Overall Water Splitting

“…Facing the energy crisis and the detrimental impact of environmental pollution, it's urgent to develop sustainable and renewable clean hydrogen (H 2 ) energy through electrocatalytic water splitting to meet future demands. [1][2][3][4][5][6] Unfortunately, both hydrogen evolution and oxygen evolution reactions (HER and OER) involved in water splitting need to burden considerable overpotentials (η) due to the dynamically unfavorable activation. [7] Thus, highly active electrocatalysts are required in the water splitting process.…”