Composites Part B 183 (2020) 107655

Available online 6 December 20191359-8368/© 2019 Elsevier Ltd. All rights reserved.

Synthesis of NiOx@NPC composite for high-performance supercapacitor via waste PET plastic-derived Ni-MOF

Abdullah M. Al-Enizi a,*, Mohd Ubaidullah a, Jahangeer Ahmed a, Tansir Ahamad a, Tokeer Ahmad b, Shoyebmohamad F. Shaikh a, Mu. Naushad a

a Department of Chemistry, College of Science, King Saud University, Riyadh, 11451, Saudi Arabia b Nanochemistry Lab, Department of Chemistry, Jamia Millia Islamia, New Delhi, 110025, India

A R T I C L E I N F O

Keywords: Waste PET plastic Metal organic frameworks Mesoporous Nanocomposites High surface area Highly efficient supercapacitor

A B S T R A C T

Metal–organic frameworks (MOFs) have come up as potential advance materials for energy applications owing to high surface area and tuneable porosity. The poor electrical conductivity and stability of MOFs restrict their vital use in supercapacitor applications. Herein, a smart approach was employed to synthesize NiOx nanoparticles decorated with nitrogenous porous carbon (NiOx@NPC nanocomposite) via PET-derived MOFs. The nitrogenous porous carbon not merely enhanced the electrical conductivity and stability but as well improved the charge relocation operation for the better performance of supercapacitor devices. The as-prepared NiOx@NPC com-posite demonstrated high specific surface area of 1523 m2/g for the first time. In a three-electrode setup the as synthesized NiOx@NPC composite electrode demonstrated an excellent specific capacitance of 581.30 F/g at a scan rate of 5 mV/s. Moreover, the fabricated symmetric supercapacitor (2E system) device demonstrated a specific capacitance of 291 F/g at a scan rate of 5 mV/s using 6 M KOH electrolyte. The excellent cyclic stability of the NiOx@NPC composite was obtained after running 5000 segments of CV at a sweep rate of 50 mV/s. Thus, the obtained results show that NiOx@NPC composites certify and support the novelty of the materials for next- generation energy applications.

1. Introduction

Nitrogen doped carbon materials with excellent porosity, high sur-face area and good electrical conductivity have attracted significant scientific interest owing to their excellent physical/chemical charac-teristics and various functionalities [1–4]. The energy storage means for instance electrochemical supercapacitors require excellent electrical conductivity, large surface area/porosity, and electro-chemical stability [5–7]. Evidently, the functioning of energy storage devices mainly based on the interaction of ions and transportation of electrons within the material [8,9]. For instance, an ideal, carbon material-based electro-chemical supercapacitor needs high electrical conductivity for electron transportation [10–12]. Moreover, high surface area and suitable pore architecture play an important role [13–17] in ensuring an effective adsorption/desorption and rapid accession of electrolyte ions to the surface of a material [18,19]. Presently, traditional porous carbon ob-tained from firewood [20], coal [21], fruit peel [21], biomass [22], sugar cane bagasse [20], coffee beans [23], coconut shell [23], and rice

husk [24] has attracted tremendous attention because of its high surface area [24]. However, its large pore tortuosity generates poor connectivity of the pores that prohibits the easy transportation of electrolyte ions [25, 26].

In recent environmental issues, the excessive use (food packaging, X- ray films, audio and video tapes, and soft drinks) of disposable poly (ethylene terephthalate) (PET) bottles has received great concern due to their non-biodegradability nature [27]. From global statistics, the overall consumption of PET amounts to 50–60 Mt a year and continues to increase [28]. Hence, recycling of PET not merely serve as a partial solution to the environmental issues but also provides the raw materials for energy storage applications [29]. Sinha et al. reported that recycled plastic derived product that can result of 50–60% energy savings as compared to produce from virgin resin [30]. This would achieve veri-table elimination of waste while creating useful materials such as MOFs.

MOFs are a novel class porous crystalline materials composed of metal ions and organic linkers [31,32] on account of having tailorable physical and chemical properties, for instance; high specific surface

* Corresponding author. E-mail address: amenizi@ksu.edu.sa (A.M. Al-Enizi).

Contents lists available at ScienceDirect

Composites Part B

journal homepage: www.elsevier.com/locate/compositesb

https://doi.org/10.1016/j.compositesb.2019.107655 Received 29 July 2019; Received in revised form 27 October 2019; Accepted 28 November 2019

Composites Part B 183 (2020) 107655

2

area, excellent pores architecture, and versatile functionalities [33,34]. MOFs fascinated immense consideration in energy storage applications [35]. Recently, numerous research attempts have been directed toward developing new MOFs structures by replacing with different metal species to effectively enhance their surface area [36], porosity [36], and electrical conductivity [37]. Meanwhile, MOF itself serves as an excel-lent carbon precursor due to its high carbon content [37]. MOFs origi-nated carbons are made by elevated temperature carbonization, i.e., porous MOFs with considerable pore volume and controllable pore size [38].

Though, the capacity of MOFs, as a recent category of functional materials, has not been sufficiently investigated to resolve the hurdles in energy sector due to MOFs are typically poor electrical conductors [39]. Moreover, considerable attempts have been attained to enhance the conductivity of MOFs-based electrodes [40]. Jiao et al. described Ni-MOF and revealed the fast electron transfer rate due to conjugated π bonding, which demonstrated a high super capacitive efficiency of 55.8 Wh/kg, and 7000 W/kg [41]. Banerjee et al. reported Ni-MOF/rGO composites and accomplished a good capacitive performance of 758 F/g, with an energy density of 37.8 Wh/kg, and power density of 227 W/kg [42]. Nitrogen-doped porous carbon obtained from Ni-MOF was reported by Zhao et al., which showed a brilliant electrochemical results with 2002.6 F/g at 1 A/g, and great cycling stability (91.5% of retention at 10 A/g current density after 5 thousand cycles), as promising super-capacitor materials [43].

In this work, nickel oxide nanoparticles were incorporated in N- doped porous carbon (NiOx@NPC) composite prepared using a cost effective and simple solvothermal route. Furthermore, the as- synthesized NiOx@NPC composite, derived from the carbonization of porous Ni-MOF, showed notably high specific surface area (1523 m2/g) and meso pores (13 nm and 11 nm) after applying Barrett Joyner Halenda (BJH) and Dubinin-Astakhov (DA) studies. Through the syn-ergistic effect between meso pores, the NiOx@NPC composite showed remarkably high ion approachable surface and small ion diffusion resistance. The NiOx@NPC composite showed an excellent specific capacitance of 581.30 F/g at 5 mV/s in 3Esystem. In addition, NiOx@NPC composite was used to fabricate symmetric supercapacitor (2E system) that demonstrated a specific capacitance of 290.65 F/g@ 5 mV/s in 6 M KOH electrolyte, which suggested the potential application of NiOx@NPC composite in supercapacitors.

2. Experimental

2.1. Chemicals

AR quality chemicals and solvents were utilized except additional purification. Zinc nitrate hexa-hydrate (98%, Zn(NO3)2⋅6H2O), nickel nitrate hexa-hydrate (99.9%, Ni(NO₃)₂⋅6H₂O), and potassium hydroxide (�85%) were purchased from the Sigma Aldrich. N–N-diethyl form-amide (DEF) (Alfa Aesar, 99%) and Triethylenediamine (98%) were purchased from Alfa Aesar Co., Inc., and PET-derived benzene-1,4- dicarboxylic acid (BDC) was used.

2.2. Depolymerisation of waste PET bottles

Waste PET bottles were utilized to produce BDC. For this purpose, waste PET bottles were collected and washed using distilled water, and then cut into small pieces. Briefly, 1 g of PET pieces was kept in a Teflon high-pressure reactor with 20 and 30 mL of ethylene glycol and distilled water respectively. This was then treated at 180 �C for 4 h. Thereafter, the mixture was get cooled at a temperature of 27 �C. Furthermore, this precipitate was transferred to a centrifuge tube. The resulting product was taken out and dried at 100 �C for 20 h. The white precipitate i.e., BDC was utilized as a starting material for the production of MOFs. Herein, we reported the Fourier-transform infrared (FT–IR) spectra of our PET plastic-derived BDC to confirm the formation of BDC (Fig. S1y).

2.3. One-pot synthesis of Ni-MOF by using PET plastic derived BDC

In a simple synthesis procedure, 10 mM of Ni(NO3)2⋅6H2O was dis-solved in 70 mL of DEF in a flask, and 4 mM of BDC was dissolved in 70 ml of DEF in another beaker. After mixing both solutions, 1.4 mM of triethylenediamine was added to this reaction mixture with constant stirring. This reaction mixture was heated at 100 �C for 24 h under auto- genous high-pressure in a Teflon reactor. Crystals of Ni-MOF were ob-tained and collected via centrifugation at 7000 rpm for 20 min. Light green crystals of Ni-MOF were washed twice with DEF, followed by evacuation at 80 �C under vacuum (<10� 7 bar). The as-synthesized crystals of Ni-MOF were carbonized under a constant flow of nitrogen at 750 �C for 5 hh @ heating and cooling rate of 2� per minute. The resultant greenish black mass of Ni-MOF was referred to as NiOx@NPC composite (NPC: nitrogen-doped porous carbon) (Scheme 1).

Scheme 1. Schematic illustration of the preparation process.

A.M. Al-Enizi et al.

Composites Part B 183 (2020) 107655

3

2.4. Characterization techniques

The texture and surface morphologies of NiOx@NPC composite were characterized through field emission scanning electron microscopy (JEOL, FE-SEMJSM-7600F). The high resolution transmission electron microscopy (FEI Technai G2 20, HR-TEM) was employed to estimate the shape and size. The carbon and nitrogen contents present in NiOx@NPC were analysed via CHN (Agilent 730), whereas inductively coupled plasma-optical emission spectrometry (Varian VISTA-MPX, ICP-OES) was performed to estimate the percentage of metal content. For ICP measurement, the standard solutions of 1, 2, 5, 10, 20, 30 ppm, 40, and 50 ppm were prepared. Crystallinity of NiOx@NPC composite was characterized using the Rigaku-Ultima-IV X-ray machine (λ ¼ 0.1542 Å). The diffraction pattern was recorded in two-theta range of 20�–70�. The thermo-gravimetric analysis (TGA) using SDT Q600 (TA instrument, USA) was performed to understand the thermal behaviour of NiOx@NPC composite The Fourier transform-infrared spectra (FT-IR) of NiOx@NPC composite was analysed in 400–4000 cm� 1 on IT Affinity-1, Shimadzu, using potassium bromide power pellet. XPS analysis was carried out by using X-ray photoelectron spectroscopy (XPS) (Thermo Scientific ESCA LAB 250 Xi, USA). Brunauer-Emmett-Teller (BET) sur-face area, pore size, and pore volume were examined via a Micromeritics ASAP-2020 Autosorb gas sorption analyzer in liquid Nitrogen at � 196.15 �C. The supercapacitor performance of NiOx@NPC composite electrode was performed with 3and 2-electrode systems. The super-capacitor electrode was fabricated using Ni-foam (1 cm2) as a current collector in 6 M KOH electrolyte. The cyclic voltammetry (CV), galva-nostatic charge/discharge (GCD), and electrochemical impedance spectroscopic (EIS) analysis was examined at 27 �C on the CHI-660E electrochemical workstation.

3. Results and discussion

3.1. Electron microscopic studies

The FE–SEM demonstrated the well-defined crystalline pristine cubic structures of the prepared Ni-MOF before carbonization, (Fig. 1a). After carbonization (i.e., NiOx@NPC composite), the pristine cubical struc-ture is not retained and converts into a plate-like agglomerated morphology, as shown in Fig. 1b. FE-SEM micrographs of the NiOx@NPC composite reveal that the small nanoparticles of NiOx are

incorporated hierarchically in porous carbon matrix. Such morphology facilitates to passage the interior surface of the material, which promotes an easy infiltration and charge transportation of electrolyte ions with minimum diffusion lengths [44,45]. To gather more insight regarding the crystal growth, HR-TEM was performed. The HR-TEM micrographs of NiOx@NPC composite are exhibited in Fig. 1c and 1d. The NiOx nanoparticles incorporated uniformly into the carbon matrix, rendering a good connect and enhancing the electrical conductivity of the material [46]. In a typical HR-TEM image, two different kinds of lattice fringes were found, as shown in Fig. 1c. 0.280 nm lattice spacing corroborates to the (002) plane of the face-centred cubic of Ni2O3, and 0.241 nm lattice spacing coincide with (111) plane of the cubic NiO phase. The respective selected area electron diffraction (SAED) pattern of NiOx@NPC com-posite demonstrated the diffraction rings that were directed toward the crystal faces from inward to outward direction. Fig. 1d shows the SAED patterns that are indexed to (002), (111), (200), (004), (020), and (220) planes, and corroborates well with the X-ray diffraction (XRD) data. From the CHN results, we found that approximately 34.55% of carbon and 5.80% of nitrogen were present in the NiOx@NPC composite. The good amount of nitrogen present in the carbon matrix can foster the electrical conductivity on grounds of the formation of a large number of defects. ICP-OES analysis was performed to check Ni percentage in NiOx@NPC composite and was found to be 25.35%, as shown in Table 1.

3.2. Structural interpretation

The powder x-ray diffraction pattern of NiOx@NPC composite revealed the formation of mixed phases containing the cubic shape of NiO (JCPDS No. 47–1049), face-centred cubic phase of Ni2O3, and cubic phase of Ni, as shown in Fig. 2a [47]. The intense diffraction patterns of NiOx@NPC composite confirmed the highly crystalline nature of the synthesized material. The distinct peaks of NiO at 2θ of 35.50�, 41.85�, 51.10�, and 60.60� clearly indicated various diffraction planes of [111, [200], [004], and [220]. Rest of the peaks observed at two-theta of 30.64�, 56.15�, and 68.25�, correspond to [002], [202], and [004] plane of Ni2O3crystal. One small peak was at 2θ of 45.70� belonged to Ni [111] plane. The formation of carbon matrix was confirmed by the prominent carbon peak (002) at 2θ of 21.60�. However, zero impurity phase was detected, which confirmed the high purity of NiOx@NPC composite. Fig. 2b illustrates the TGA analysis of NiOx@NPC composite, two curves of weight loss were observed. The first curve shows the weight destruction of 2.3% that occurred at the temperature of up to 260 �C, ascribing the loss of physically adsorbed moisture, and solvents from the pores of NiOx@NPC composite. While at 430 �C, the weight loss of 56.2% was observed because of the decomposition of the carbon matrix. In Fig. 2c, the FTIR spectra of NiOx@NPC composite exhibits bands at 1623 cm� 1 and 1402 cm� 1, corresponding to the stretching of C–C and C––O functional groups [48]. The broad IR-band about 3212 cm� 1 can be attributed to the stretching vibrations of –OH due to the absorbed water during pellet preparation [49–51]. The bands at 1176 cm� 1 and 1020 cm� 1 are correspond to the stretching vibration of C–O and C–N [49]. The absorption band at low intensity region confirmed the for-mation of NiOx. The XRD and FT-IR results confirmed the formation of NiOx@NPC composite.

3.3. XPS analysis

The XPS measurements determined the surface elemental composi-tion of NiOx@NPC composite as shows in Fig. 3a-d and indicated the existence of Carbon, Nitrogen, Oxygen, and Nickel. Fig. 3a demonstrated

Fig. 1. FE-SEM micrographs of (a) Ni-MOF (b) Ni-MOF, and after carboniza-tion, (c) HR-TEM of NiOx@NPC composite, and (d) SAED pattern of NiOx@NPC composite.

Table 1

Weight Percentage (%)

Compound C H N O Ni NiOx@NPC 34.55 2.01 5.80 32.12 25.35

A.M. Al-Enizi et al.

Composites Part B 183 (2020) 107655

4

the survey spectrum of binding energy of NiOx@NPC composite. The high resolution spectrum of C1s can be fitted to five peaks marked at 288.59, 287.19, 286.13, 284.93 and 283.67eV can be assigned to the

C––O, O–C––O, C–N or C––N, and C–C or C––C respectively [43]. Graphitization of carbon was confirmed by the prominent peak marked at 283.67 eV (C–C/C––C) [43]. The wide spectrum of N1s of NiOx@NPC

Fig. 2. (a) Powder X-ray diffraction pattern, (b) TGA, and (c) FTIR spectra of NiOx@NPC composite. The symbols denoted in X-ray diffraction pattern are Ni ¼ *, Ni2O3 ¼ #

Fig. 3. (a) XPS survey spectra NiOx@NPC composite, (b) high-resolution C 1s spectrum (c) high-resolution N 1s spectrum (d) high resolution Ni 2p spectrum.

A.M. Al-Enizi et al.

Composites Part B 183 (2020) 107655

5

composite shown in Fig. 3c, which can be fitted with three N peaks labelled at 399.70, 399.18 and 397.09 eV respectively. The de-convolution of the Ni2p peak in NiOx@NPC composite demonstrated in Fig. 3d. Two high resolution peaks at a binding energy of 875.84 and 858.60 eV matched to Ni 2p1/2 and Ni 2p3/2, respectively. The O1s peak marked at a binding energy of 531.93 eV which confirmed the presence of oxygen in the NiOx@NPC composite.

Fig. 4. Brunauer–Emmett–Teller surface area and pore size distribution of NiOx@NPC composite: (a) BET plot, (b) N2 adsorption–desorption isotherms, (c) BJH pore size distribution, and (d) DA pore size distribution.

Table 2

Compound SBET

m2g� 1 BJH Pore Size Distribution (nm)

DA Pore Size Distribution (nm)

Pore Volume cm3/g

NiOx@NPC 1523 13 11 1.134

Fig. 5. Electrochemical performance of NiOx@NPC composite in three-electrode system (a) CV at different scan rates ranging from 5 mV/s to 200 mV/s (b) Specific capacitance graph calculated from CV at different sweep rates, (c) GCD curves evaluated at different current densities ranging from 1 A g� 1 to 12 A g� 1, (d) Nyquist plots at frequency range of 0.01 Hz–100 kHz in 6 M KOH electrolyte.

A.M. Al-Enizi et al.

Composites Part B 183 (2020) 107655

6

3.4. Surface area and porosity

Specific surface area and pore architecture of the materials perform an essential function in various energy storage applications [52]. Spe-cific surface area and porosity of NiOx@NPC composite were deter-mined via the N2 adsorption and desorption analysis. The straight line depicted in Fig. 4a demonstrates the multipoint BET plot in the relative pressure (P/P0) range of 0.05–0.35. The Nitrogen adsorption desorption isotherm of NiOx@NPC composite matched with type IV isotherms followed by H3 hysteresis is an evident of the capillary condensation in meso pores [53–55]. The monolayer and multilayer adsorption was confirmed by the behaviour of N2 adsorption–desorption isotherm (Fig. 4b) [56]. Moreover, in the middle part of the isotherm, the low slop region attributed to the multilayer adsorption [57]. For the first time, notably high specific surface area of ~1523 m2/g was obtained for NiOx@NPC composite. Such a large surface area could be by virtue the unique porous architecture of Ni-MOF, which turned into plate-like morphology after carbonization, as depicted in FE-SEM (Fig. 1b). The mesoporous nature of NiOx@NPC composite was confirmed by the BJH (Fig. 4c) and DA (Fig. 4d) pore size analysis, which was found to be 13 nm and 11 nm, respectively. Large surface area and mesoporosity of NiOx@NPC composite suggested more active sites available on the composite surface. Table 2 comprises the specific surface area, pore size (BJH/DA), and pore volume of NiOx@NPC composite.

3.5. Electrochemical performance

The working electrode of NiOx@NPC composite was prepared using an active material and poly vinylidene difluoride in the mass ratio of 95:5 with small amount of N-methyl 2-pyrrolidinone solution. This produced viscous slurry that was painted on a Ni-foam (1 � 1 cm) and de humidified under vacuum at 100 �C for 10 h. CV and GCD analysis was performed in 6 M KOH electrolyte to estimate the electrochemical per-formance of NiOx@NPC composite in three and two-electrode systems. The cyclic voltammetry of NiOx@NPC composite electrode conducted with 3-electrode setup at different scan rates in � 0.5 V to 0.5 V potential range as shown in Fig. 5a. The value of specific capacitance calculated by CV analysis for NiOx@NPC composite (Fig. 5b) decreased steadily from 581 to 342 F/g as the scan rate enhanced form 5–200 mV/s. Moreover, the performance of the material was also investigated by performing galvanostatic charge-discharge (GCD) experiments at sepa-rate current densities, as revealed in Fig. 5c. EIS was also performed to check the corresponding Nyquist plots as shown in Fig. 5d. Nyquist plot mainly comprise of a small semicircle ensued by a straight. The small semicircle revealed the small value (~2 Ω) of charge transfer resistance (Rct). The results indicated that NiOx@NPC exhibited superior elec-trochemical performance [58]. The symmetrical and linear nature of GCD curves demonstrated a high columbic efficiency [59] of NiOx@NPC composite. Table 3 illustrates the specific capacitance of NiOx@NPC composite estimated by CV and GCD at different sweep rates and current densities. The symmetrical super capacitive behaviour of the material was checked via the two-electrode setup in 6 M KOH electrolyte. Fig. 6a

Table 3

Specific Capacitance (F g� 1)

Compound Sweep Rate (mV s� 1) Current Density (A g� 1)

5 10 25 50 100 200 1 3 5 9 12 NiOx@NPC 581 531 472 452 397 342 534 498 480 432 312

Fig. 6. Electrochemical performance of NiOx@NPC composite in two electrode system (a) CV at different scan rates ranging from 5 mV/s to 200 mV/s (b) Specific capacitance graph calculated from CV at different scan rates, (c) GCD curves evaluated at different current densities ranging from 1 A g� 1 to 12 A g� 1, of (d) 5000 segments of cyclic stability at 50 mV/s in 6 M KOH electrolyte.

A.M. Al-Enizi et al.

Composites Part B 183 (2020) 107655

7

and b demonstrate the CV curves and specific capacitance scanned from 5 to 200 mV/s sweep rates, with the splendid values of specific capac-itance ranging from 291 to 171 F/g. The cyclic stability of the material perform a significant role in energy storage devices [60]. The long-term electrochemical cyclic stability of NiOx@NPC composite was tested after running 5000 segments of CV at scan rate of 50 mV/s, as revealed in Fig. 6d.

Moreover, a conductive network was formed between mesoporous carbon and metal oxide (NiOx) nanoparticles, and the pores in the car-bon matrix worked as a store tank for electrolyte ions [61]. The rapid transport of ions and stable supply of electrolyte ions can be ensured by these reservoirs [62]. The mesoporosity and high surface area of NiOx@NPC composite indicates that the materials can be utilized as a competent electrode material for energy storage applications [63].

4. Conclusions

In summary, a novel NiOx@NPC composite was synthesized from PET plastic-derived Ni-MOF with an exceptionally high surface area and porosity via simple and cost-effective hydrothermal route. The as- prepared NiOx@NPC composite exhibits higher specific capacitance (581 F/g) in 6 M KOH electrolyte at 5 mV/s scan rate with 3-electrode system. This excellent specific capacitance might be due to the high value of specific surface area (1523 m2/g) and mesoporosity (~12 nm) shown by the materials. The excellent cyclic stability of the NiOx@NPC composite was confirmed after running 5000 segments of CV at scan rate of 50 mV/s.

Declaration of competing interest

There are no conflicts to declare.

Acknowledgements

The authors acknowledge funding from the Research and Develop-ment (R&D) Program (Research Pooling Initiative), Ministry of Educa-tion, Riyadh, Saudi Arabia, (RPI-KSU).

Appendix A. Supplementary data

Supplementary data related to this article can be found at https://do i.org/10.1016/j.compositesb.2019.107655.

References

[1] Wang F, Zhu L, Pan Y, Li Z, Yang P, Song M, et al. From ZIF nanoparticles to hierarchically porous carbon: toward very high surface area and high-performance supercapacitor electrode materials. Inorg Chem Front 2019;6:32–9. https://doi. org/10.1039/C8QI00832A.

[2] Ma Z, Kyotani T, Liu Z, Terasaki O, Tomita A. Very high surface area microporous carbon with a three-dimensional nano-array structure: synthesis and its molecular structure. Chem Mater 2001;13:4413–5. https://doi.org/10.1021/cm010730l.

[3] Zuo L, Chen S, Wu J, Wang L, Hou H, Song Y. Facile synthesis of three-dimensional porous carbon with high surface area by calcining metal–organic framework for lithium-ion batteries anode materials. RSC Adv 2014;4:61604–10. https://doi.org/ 10.1039/C4RA10575C.

[4] To JWF, Chen Z, Yao H, He J, Kim K, Chou H-H, et al. Ultrahigh surface area three- dimensional porous graphitic carbon from conjugated polymeric molecular framework. ACS Cent Sci 2015;1:68–76. https://doi.org/10.1021/ acscentsci.5b00149.

[5] Naoi K, Naoi W, Aoyagi S, Miyamoto J, Kamino T. New generation “nanohybrid supercapacitor”. Acc Chem Res 2013;46:1075–83. https://doi.org/10.1021/ ar200308h.

[6] Conder J, Fic K, Ghimbeu CM. 10 - supercapacitors (electrochemical capacitors). In: Jeguirim M, Limousy L, editors. Char carbon mater. Deriv. From biomass. Elsevier; 2019. p. 383–427. https://doi.org/10.1016/B978-0-12-814893-8.00010- 9.

[7] Pandit B, Bommineedi LK, Sankapal BR. Electrochemical engineering approach of high performance solid-state flexible supercapacitor device based on chemically synthesized VS2 nanoregime structure. J Energy Chem 2019;31:79–88. https://doi. org/10.1016/j.jechem.2018.05.011.

[8] Wang Y, Fu X, Zheng M, Zhong W-H, Cao G. Strategies for building robust traffic networks in advanced energy storage devices: a focus on composite electrodes. Adv Mater 2019;31:1804204. https://doi.org/10.1002/adma.201804204.

[9] Helms BA, Seferos DS. Virtual issue: designing polymers for use in electrochemical energy storage devices. Macromolecules 2019;52:1349–53. https://doi.org/ 10.1021/acs.macromol.9b00035.

[10] Kaempgen M, Chan CK, Ma J, Cui Y, Gruner G. Printable thin film supercapacitors using single-walled carbon nanotubes. Nano Lett 2009;9:1872–6. https://doi.org/ 10.1021/nl8038579.

[11] Zhai Y, Dou Y, Zhao D, Fulvio PF, Mayes RT, Dai S. Carbon materials for chemical capacitive energy storage. Adv Mater 2011;23:4828–50. https://doi.org/10.1002/ adma.201100984.

[12] Hu N, Zhang L, Yang C, Zhao J, Yang Z, Wei H, et al. Three-dimensional skeleton networks of graphene wrapped polyaniline nanofibers: an excellent structure for high-performance flexible solid-state supercapacitors. Sci Rep 2016;6:19777.

[13] Naushad M. Surfactant assisted nano-composite cation exchanger: development, characterization and applications for the removal of toxic Pb2þ from aqueous medium. Chem Eng J 2014;235:100–8. https://doi.org/10.1016/J. CEJ.2013.09.013.

[14] Naushad M, Sharma G, Alothman ZA. Photodegradation of toxic dye using Gum Arabic-crosslinked-poly(acrylamide)/Ni(OH)2/FeOOH nanocomposites hydrogel. J Clean Prod 2019;241:118263. https://doi.org/10.1016/j.jclepro.2019.118263.

[15] Liu Z, Yuan X, Zhang S, Wang J, Huang Q, Yu N, et al. Three-dimensional ordered porous electrode materials for electrochemical energy storage. NPG Asia Mater 2019;11:12. https://doi.org/10.1038/s41427-019-0112-3.

[16] Chaplin BP. The prospect of electrochemical technologies advancing worldwide water treatment. Acc Chem Res 2019;52:596–604. https://doi.org/10.1021/acs. accounts.8b00611.

[17] Abouelamaiem DI, Mostazo-L�opez MJ, He G, Patel D, Neville TP, Parkin IP, et al. New insights into the electrochemical behaviour of porous carbon electrodes for supercapacitors. J Energy Storage 2018;19:337–47. https://doi.org/10.1016/j. est.2018.08.014.

[18] Cheng J, Xu Q, Wang X, Li Z, Wu F, Shao J, et al. Ultrahigh-surface-area nitrogen- doped hierarchically porous carbon materials derived from chitosan and betaine hydrochloride sustainable precursors for high-performance supercapacitors. Sustain Energy Fuels 2019;3:1215–24. https://doi.org/10.1039/C9SE00072K.

[19] Pham DT, Sambandam B, Kim S, Jo J, Kim S, Park S, et al. Dandelion-shaped manganese sulfide in ether-based electrolyte for enhanced performance sodium-ion batteries. Commun Chem 2018;1:83. https://doi.org/10.1038/s42004-018-0084- 1.

[20] Girgis B S, Khalil L B, Tawfik T AM. Activated carbon from sugarcane bagasse carbonization in the presence of inorganic acids. J Chem Technol Biotechnol 1994; 61:87–92. https://doi.org/10.1002/jctb.280610113.

[21] Tong F, Jia W, Pan Y, Guo J, Ding L, Chen J, et al. A green approach to prepare hierarchical porous carbon nanofibers from coal for high-performance supercapacitors. RSC Adv 2019;9:6184–92. https://doi.org/10.1039/ C8RA08949C.

[22] Zhao H, Cheng Y, Lv H, Ji G, Du Y. A novel hierarchically porous magnetic carbon derived from biomass for strong lightweight microwave absorption. Carbon N Y 2019;142:245–53. https://doi.org/10.1016/j.carbon.2018.10.027.

[23] Yun YS, Park MH, Hong SJ, Lee ME, Park YW, Jin H-J. Hierarchically porous carbon nanosheets from waste coffee grounds for supercapacitors. ACS Appl Mater Interfaces 2015;7:3684–90. https://doi.org/10.1021/am5081919.

[24] Teo EYL, Muniandy L, Ng E-P, Adam F, Mohamed AR, Jose R, et al. High surface area activated carbon from rice husk as a high performance supercapacitor electrode. Electrochim Acta 2016;192:110–9. https://doi.org/10.1016/j. electacta.2016.01.140.

[25] Dutta S, Bhaumik A, Wu KC-W. Hierarchically porous carbon derived from polymers and biomass: effect of interconnected pores on energy applications. Energy Environ Sci 2014;7:3574–92. https://doi.org/10.1039/C4EE01075B.

[26] Sattayarut V, Chanthad C, Khemthong P, Kuboon S, Wanchaem T, Phonyiem M, et al. Preparation and electrochemical performance of nitrogen-enriched activated carbon derived from silkworm pupae waste. RSC Adv 2019;9:9878–86. https://doi. org/10.1039/C9RA01090D.

[27] The cost of plastic packaging. C&EN Glob Enterp 2016;94:32–7. https://doi.org/ 10.1021/cen-09441-cover.

[28] Volanti M, Cespi D, Passarini F, Neri E, Cavani F, Mizsey P, et al. Terephthalic acid from renewable sources: early-stage sustainability analysis of a bio-PET precursor. Green Chem 2019;21:885–96. https://doi.org/10.1039/C8GC03666G.

[29] Pongr�acz E. The environmental impacts of packaging. Environ Conscious Mater Chem Process 2007:237–78. https://doi.org/10.1002/9780470168219.ch9. John Wiley & Sons, Ltd.

[30] Sinha V, Patel MR, Patel JV. Pet waste management by chemical recycling: a review. J Polym Environ 2010;18:8–25. https://doi.org/10.1007/s10924-008- 0106-7.

[31] Lee J, Lim D-W, Dekura S, Kitagawa H, Choe W. Mop � MOF: collaborative combination of metal–organic polyhedra and metal–organic framework for proton conductivity. ACS Appl Mater Interfaces 2019;11:12639–46. https://doi.org/ 10.1021/acsami.9b01026.

[32] Yao M, Zhao X, Jin L, Zhao F, Zhang J, Dong J, et al. High energy density asymmetric supercapacitors based on MOF-derived nanoporous carbon/manganese dioxide hybrids. Chem Eng J 2017;322:582–9. https://doi.org/10.1016/j. cej.2017.04.075.

[33] McKinstry C, Cathcart RJ, Cussen EJ, Fletcher AJ, Patwardhan SV, Sefcik J. Scalable continuous solvothermal synthesis of metal organic framework (MOF-5)

A.M. Al-Enizi et al.

Composites Part B 183 (2020) 107655

8

crystals. Chem Eng J 2016;285:718–25. https://doi.org/10.1016/j. cej.2015.10.023.

[34] Li H, Eddaoudi M, O’Keeffe M, Yaghi OM. Design and synthesis of an exceptionally stable and highly porous metal-organic framework. Nature 1999;402:276.

[35] Wei X, Li Y, Peng H, Gao D, Ou Y, Yang Y, et al. A novel functional material of Co3O4/Fe2O3 nanocubes derived from a MOF precursor for high-performance electrochemical energy storage and conversion application. Chem Eng J 2019;355: 336–40. https://doi.org/10.1016/j.cej.2018.08.009.

[36] McGuire CV, Forgan RS. The surface chemistry of metal–organic frameworks. Chem Commun 2015;51:5199–217. https://doi.org/10.1039/C4CC04458D.

[37] Sun W, Tao X, Du P, Wang Y. Carbon-coated mixed-metal sulfide hierarchical structure: MOF-derived synthesis and lithium-storage performances. Chem Eng J 2019;366:622–30. https://doi.org/10.1016/j.cej.2019.01.178.

[38] Liu B, Shioyama H, Jiang H, Zhang X, Xu Q. Metal-organic framework (MOF) as a template for syntheses of nanoporous carbons as electrode materials for supercapacitor. Carbon N Y 2010;48:456–63. https://doi.org/10.1016/j. carbon.2009.09.061.

[39] Vaughan O. A conductive guest. Nat Nanotechnol 2014. https://doi.org/10.1038/ nnano.2014.18.

[40] Bhardwaj SK, Bhardwaj N, Kaur R, Mehta J, Sharma AL, Kim K-H, et al. An overview of different strategies to introduce conductivity in metal–organic frameworks and miscellaneous applications thereof. J Mater Chem 2018;6: 14992–5009. https://doi.org/10.1039/C8TA04220A.

[41] Jiao Y, Pei J, Yan C, Chen D, Hu Y, Chen G. Layered nickel metal-organic framework for high performance alkaline battery-supercapacitor hybrid devices. J Mater Chem 2016;4:13344–51. https://doi.org/10.1039/c6ta05384j.

[42] Banerjee PC, Lobo DE, Middag R, Ng WK, Shaibani ME, Majumder M. Electrochemical capacitance of Ni-doped metal organic framework and reduced graphene oxide composites: more than the sum of its parts. ACS Appl Mater Interfaces 2015;7:3655–64. https://doi.org/10.1021/am508119c.

[43] Yang H-X, Zhao D-L, Meng W-J, Zhao M, Duan Y-J, Han X-Y, et al. Nickel nanoparticles incorporated into N-doped porous carbon derived from N-containing nickel-MOF for high-performance supercapacitors. J Alloy Comp 2019;782: 905–14. https://doi.org/10.1016/j.jallcom.2018.12.259.

[44] Kim M, Oh I, Kim J. Effects of different electrolytes on the electrochemical and dynamic behavior of electric double layer capacitors based on a porous silicon carbide electrode. Phys Chem Chem Phys 2015;17:16367–74. https://doi.org/ 10.1039/C5CP01728A.

[45] Wu Z, Li L, Yan J, Zhang X. Materials design and system construction for conventional and new-concept supercapacitors. Adv Sci 2017;4:1600382. https:// doi.org/10.1002/advs.201600382.

[46] Kumar R, Kumari S, Dhakate SR. Nickel nanoparticles embedded in carbon foam for improving electromagnetic shielding effectiveness. Appl Nanosci 2015;5: 553–61. https://doi.org/10.1007/s13204-014-0349-7.

[47] Srivastava DN, C Srivastava P. Realizing NiO nanocrystals from a simple chemical method. Bull Mater Sci 2010;33:653–6. https://doi.org/10.1007/s12034-011- 0142-0.

[48] Hussain M, Rahman M, Asiri AM. Ultrasensitive and selective 4-aminophenol chemical sensor development based on nickel oxide nanoparticles decorated carbon nanotube nanocomposites for green environment. J Environ Sci 2017;53. https://doi.org/10.1016/j.jes.2016.03.028.

[49] Kottegoda IRM, Idris NH, Lu L, Wang J-Z, Liu H-K. Synthesis and characterization of graphene–nickel oxide nanostructures for fast charge–discharge application.

Electrochim Acta 2011;56:5815–22. https://doi.org/10.1016/j. electacta.2011.03.143.

[50] Naushad M, Ahamad T, Sharma G, Al-Muhtaseb AH, Albadarin AB, Alam MM, et al. Synthesis and characterization of a new starch/SnO2 nanocomposite for efficient adsorption of toxic Hg2þ metal ion. Chem Eng J 2016;300:306–16. https://doi. org/10.1016/j.cej.2016.04.084.

[51] Naushad M, Ahamad T, AlOthman ZA, Al-Muhtaseb AH. Green and eco-friendly nanocomposite for the removal of toxic Hg(II) metal ion from aqueous environment: adsorption kinetics & isotherm modelling. J Mol Liq 2019. https:// doi.org/10.1016/j.molliq.2019.01.090.

[52] Li D, Chang G, Zong L, Xue P, Wang Y, Xia Y, et al. From double-helix structured seaweed to S-doped carbon aerogel with ultra-high surface area for energy storage. Energy Storage Mater 2019;17:22–30. https://doi.org/10.1016/j. ensm.2018.08.004.

[53] Ojha DP, Song JH, Kim HJ. Facile synthesis of graphitic carbon-nitride supported antimony-doped tin oxide nanocomposite and its application for the adsorption of volatile organic compounds. J Environ Sci 2019;79:35–42. https://doi.org/ 10.1016/j.jes.2018.10.008.

[54] Mironyuk I, Tatarchuk T, Naushad M, Vasylyeva H, Mykytyn I. Highly efficient adsorption of strontium ions by carbonated mesoporous TiO2. J Mol Liq 2019. https://doi.org/10.1016/j.molliq.2019.04.111.

[55] Mironyuk IF, Gun’ko VM, Vasylyeva HV, Goncharuk OV, Tatarchuk TR, Mandzyuk VI, et al. Effects of enhanced clusterization of water at a surface of partially silylated nanosilica on adsorption of cations and anions from aqueous media. Microporous Mesoporous Mater 2019;277:95–104. https://doi.org/ 10.1016/j.micromeso.2018.10.016.

[56] Brunauer S, Emmett PH, Teller E. Adsorption of gases in multimolecular layers. J Am Chem Soc 1938;60:309–19. https://doi.org/10.1021/ja01269a023.

[57] Echeverría JC, Morera MT, Mazkiar�an C, Garrido JJ. Characterization of the porous structure of soils: adsorption of nitrogen (77 K) and carbon dioxide (273 K), and mercury porosimetry. Eur J Soil Sci 1999;50:497–503. https://doi.org/10.1046/ j.1365-2389.1999.00261.x.

[58] Ma L, Xu L, Zhou X, Xu X, Zhang L. Synthesis of a hierarchical MoSe2/C hybrid with enhanced electrochemical performance for supercapacitors. RSC Adv 2016;6: 91621–8. https://doi.org/10.1039/C6RA16157J.

[59] Singh AK, Mandal K. Engineering of high performance supercapacitor electrode based on Fe-Ni/Fe2O3-NiO core/shell hybrid nanostructures. J Appl Phys 2015; 117:105101. https://doi.org/10.1063/1.4913218.

[60] Mensah-Darkwa K, Zequine C, Kahol PK, Gupta RK. Supercapacitor energy storage device using biowastes: a sustainable approach to green energy. Sustainability 2019;11. https://doi.org/10.3390/su11020414.

[61] Song S, Ma F, Wu G, Ma D, Geng W, Wan J. Facile self-templating large scale preparation of biomass-derived 3D hierarchical porous carbon for advanced supercapacitors. J Mater Chem 2015;3:18154–62. https://doi.org/10.1039/ C5TA04721H.

[62] Sun G, Ma L, Ran J, Shen X, Tong H. Incorporation of homogeneous Co3O4 into a nitrogen-doped carbon aerogel via a facile in situ synthesis method: implications for high performance asymmetric supercapacitors. J Mater Chem 2016;4:9542–54. https://doi.org/10.1039/C6TA03884K.

[63] Ray A, Roy A, Saha S, Das S. Transition metal oxide-based nano-materials for energy storage application. In: Sato T, editor. Sci. Technol. Adv. Appl. Supercapacitors. Rijeka: IntechOpen; 2019. https://doi.org/10.5772/ intechopen.80298.

A.M. Al-Enizi et al.