High Surface Area Nanoporous Graphitic Carbon Materials Derived from Lapsi Seed with Enhanced Supercapacitance

Abstract

Nanoporous activated carbon materials derived from agro-wastes could be suitable low-cost electrode materials for high-rate performance electrochemical supercapacitors. Here we report high surface area nanoporous carbon materials derived from Lapsi seed agro-waste prepared by zinc chloride (ZnCl2) activation at 700 °C. Powder X-ray diffraction (pXRD) and Raman scattering confirmed the amorphous structure of the resulting carboniferous materials, which also incorporate oxygen-containing functional groups as confirmed by Fourier transform infrared (FTIR) spectroscopy. Scanning and transmission electron microscopy (SEM and TEM) analyses revealed the granular, nanoporous structures of the materials. High-resolution TEM (HR-TEM) confirmed a graphitic carbon structure containing interconnected mesopores. Surface areas and pore volumes of the materials were found, respectively, in the ranges from 931 to 2272 m2 g−1 and 0.998 to 2.845 cm3 g−1, and are thus superior to commercially available activated carbons. High surface areas, large pore volumes and interconnected mesopore structures of these Lapsi seed-derived nanoporous carbon materials lead to their excellent electrochemical supercapacitance performance in aqueous electrolyte (1 M H2SO4) with a maximum specific capacitance of 284 F g−1 at a current density of 1 A g−1. Furthermore, the electrodes showed high-rate capability sustaining 67.7% capacity retention even at high current density of 20 A g−1 with excellent cycle stability achieving 99% capacitance retention even after 10,000 charge–discharge cycles demonstrating the potential of Lapsi seed derived nanoporous carbons as suitable electrode materials in high-performance supercapacitor devices.

Nitrogen- and Oxygen-Containing Three-Dimensional Hierarchical Porous Graphitic Carbon for Advanced Supercapacitor

“…>C=NH + 2 e − + 2 H + ↔ >CH-NH2 (1) >C-NHOH + 2 e − + 2 H + ↔ >C-NH2 + H2O (2) >C=O + H + + e − ↔ >C-OH (carbonyl, basic) (3) >C=O + e − ↔ >C-O -(quinone, basic) O1s spectrum can be fitted into three peaks corresponding to quinone C=O (530.6 ± 0.3 eV), C-O-C (532.9 ± 0.3 eV), and O=C-OH groups (533.7 ± 0.3 eV). However, the high-resolution O 1s spectrum of HPC exhibits phenol C-OH (531.8 ± 0.3 eV), C-O-C, and O=C-OH groups (Figure 6e) [19].…”

“…>C-NHOH + 2 e − + 2 H + ↔ >C-NH2 + H2O (2) >C=O + H + + e − ↔ >C-OH (carbonyl, basic) (3) >C=O + e − ↔ >C-O -(quinone, basic) Compared with the HPC electrode, the HPGC electrode possesses a larger enclosed area at various scan rates, indicating a higher specific capacitance (Figure 8a,b). Figure 8c and d show the CV curves of two samples at scan rates from 5 to 100 mV s -1 in a voltage of −0.2-0.8V.…”

“…As a novel type of energy-storage device, supercapacitors have recently received considerable attention since they are essential components of high-rate electric devices in hybrid vehicles [1][2][3][4]. Activated carbons with a large specific surface area (SSA) over 2000 m 2 g −1 , one type of electrode materials for supercapacitors, have achieved commercial success in supercapacitor devices due to their low cost [5][6][7].…”

Activated Carbons and Their Evaluation in Electric Double Layer Capacitors

“…Apart from the HTT, the most important variable in the ZnCl 2 activation process that determines the porous structure of the resulting AC is the amount of the activating agent introduced into the precursor during impregnation. The influence of the impregnation ratio on porosity development during ZnCl 2 activation has been studied for a wide range of lignocellulosic materials [ 100 , 101 , 102 , 103 , 104 , 105 , 106 ]. For example, the relationships between the impregnation ratio (g Zn/g precursor), the volumes of micropores and mesopores and the yield of carbon obtained at 500 °C from peach stones are shown in Figure 17 .…”

Nanoporous Carbon Materials Derived from Washnut Seed with Enhanced Supercapacitance

“…ZnCl 2 contributes to creating a porous structure acting as a template; intercalated ZnCl 2 upon washing creates the void space in the carbon matrix. Recently, using various agricultural wastes or biomass such as rice husks [38], corncob [39,40], pistachio shell [41], pitch [42], bamboo [43], Batata leaves and stalks [44], Peanut dregs [45], Lapsi seed (Choerospondias axillaris) [46], etc. high surface area nanoporous carbons with large porosity, interconnected mesopores and uniform pore size distribution essentially required in supercapacitor applications have been produced.…”