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Electrochemical studies of rGO//MoO3–rGO a CV curves. b Galvanostatic charge/discharge studies (GCD). c Impedance plot. d Cyclic stability
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MoO3-reduced graphene oxide nanocomposite is synthesized in a facile, time-saving and environmental friendly microwave assisted synthesis route. The as-prepared samples, MoO3 and MoO3-reduced graphene oxide are characterized by XRD, Raman, XPS, SEM, and TEM. The characteristic studies have confirmed the formation of MoO3 and its composite matrix wi...
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Development of low-cost electrocatalyst for oxygen reduction reaction (ORR) is the main requirement for advanced chlor-alkali (ACA) cell. Herein, we report a simple and economical one-pot microwave assisted synthesis of nitrogen and phosphorus co-doped graphene (NPG) from graphene oxide in presence of ammonium dihydrogen phosphate. The optimized NP...
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... MoO 3 -carbon composite delivered high specific capacitance of 179 F/g at 50 mA/g with outstanding cycling performance over 1000 cycles. Joji et al. [20], reported that the MoO 3 -rGO was produced by a microwave synthesis process. The prepared composite shows the specific capacitance of 133.68 F/g at 3 A/g and an energy density and power density of 36.2 ...
Background: The fabrication of high-performance supercapacitor electrodes has been extensively investigated for future high power storage applications. Molybdenum trioxide (MoO3) was synthesized and the graphitic carbon nitride have been introduced with the MoO3 to enhance the electrochemical performance by synergistic effect. Methods: MoO3-gC3N4 Nanocomposite (NC) was synthesized by thermal treatment followed by sonication process and can be utilized as active material for the preparation of supercapacitor electrode. The solid-state hybrid supercapacitor device (SHSC) is fabricated with MoO3-gC3N4 NC as cathode, activated carbon as anode, and 1-ethyl-3-methylimidazolium tetrafluoroborate (EMIMBF4) ionic liquid as an ionogel electrolyte to perform the electrochemical studies. Significant findings: Cyclic voltammetry (CV) revealed that the synthesized composite delivers higher specific capacity of 520. 97 C/g at 10 mV/s. The electrochemical impedance spectroscopy (EIS) of MoO3-g-C3N4 NC reveals lower solution (Rs) and charge transfer resistance (Rct) of 0.05 and 3.14 Ω respectively. The fabricated MoO3-g-C3N4//AC SHSC delivers high energy density of 59.75 Wh/kg and a high-power density of 1125 W/kg. Furthermore, the SHSC exhibits superior cyclic stability of 86.1% even after 6000 consecutive charge-discharge cycles.
... W h Kg -1 . The nanocomposite overcomes the limitations of the hybrid effects of pseudocapacitive and EDLC performance of asymmetric supercapacitors [91]. ...
Electrochemical energy storage devices like supercapacitors and rechargeable batteries require an improvement in their performance at the commercial level. Among them, supercapacitors are beneficial in sustainable nanotechnologies for energy conversion and storage systems and have high power rates compared to batteries. High chemical and mechanical stability, huge electrical conductivity, and high specific surface area have been beneficial for selecting graphene as a supercapacitor electrode material. The excellent properties of transition metal oxides are accountable for the application in the field of energy storage. The synergistic effects of the composites of graphene derivatives with transition metal oxides will boost the performance of the devices. Recently, several studies have been done for developing supercapacitor electrodes with these nanocomposites. This review article presents an analysis of the performance of these nanocomposites with an overview of their specific capacitance, energy density, and cycling stability for supercapacitor electrode application. A brief introduction of the theory and experimental analysis of supercapacitors is also given.
... Very few reports are available on the synthesis of single crystal strip-like structure of orthorhombic MoO 3 sample [1,16]. There are various methods are available for the synthesis of single crystal a-MoO 3 like ultrasonicassisted [17] hydrothermal [18] spray pyrolysis [19] chemical co-precipitation [20], microwave technique [21], combustion route [22] etc. From these reported methods microwave and co-precipitation method combinly used for the synthesis of a-MoO 3 micro-strips hence called as microwave-assisted chemical co-precipitation method. Microwaves synthesis is rapid method due to its high power densities, fast efficient production which reduces production cost. ...
The orthorhombic MoO3 micro-strips sample was synthesized using microwave assisted chemical co-precipitation technique. Synchrotron X-ray Diffraction (SXRD) pattern and Rietveld Refinement was used to estimate structural parameter, crystallite size of sample. It reveals that the synthesized sample MoO3 crystallized as an orthorhombic phase. X-ray Absorption Spectroscopy (XAS) measurement, which comprises both X-ray Absorption Near Edge Structure (XANES) and Extended X-ray Absorption Fine Structure (EXAFS) techniques, have been carried out on Mo K-edge to probe the local structure of samples. Local structure is also confirmed from the SXRD and Raman spectra of sample. XAS measurement reveals that the first bond length of Mo-O and Mo-Mo is 1.69 and 3.42 Å in orthorhombic MoO3 respectively. Transmission electron microscopy and SAED patterns showed stripe-like structure and single-crystal formation of MoO3 respectively.
... The internal resistance (R s ) values of LaNiO 3 /g-C 3 N 4 @RGOH, LaNiO 3 /RGOH, and RGOH electrodes are 1.01 Ω, 1.23 Ω, and 1.48 Ω respectively, as well as it can be seen that LaNiO 3 /g-C 3 N 4 @RGOH has the lower charge transfer resistance (R ct ) value. The lower the charge-transfer resistance leads to an improvement in the electrochemical behavior of the composite material [55][56][57]. The cycling stability of the LaNiO 3 /g-C 3 N 4 @RGOH electrode exhibited 90.09% capacitance remaining after 2000 cycles (Fig. 5d). ...
Designing highly efficient, low-cost hybrid nanostructures with having favorable morphology and excellent conductivity is very promising for electrodes used in electrochemical storage devices. This study shows the synthesis of a new three-dimensional (3D) hybrid structure consisting of lanthanum nickel oxide (LaNiO3) perovskite, graphite carbon nitride (g-C3N4), and reduced graphene oxide hydrogel (RGOH) structures for the new hybrid supercapacitor (SC) application. The 3D hybrid structure, which is a new SC application, draws attention according to the specific capacitance (Cs) result for graphene-based hydrogel structure. For this purpose, while g-C3N4 is selected to plays an important role to increase the electrochemical activity of SC, the LaNiO3 perovskite structure is used to increase the discharge capacity of SC as well as to provide high discharge current and long cycle life. As a result of electrochemical studies, the superior capacitive performance of LaFeO3/g-C3N4@RGOH showed Cs and unique performance of 750.56 F g⁻¹ at a current density of 1 A g–1. The 3D structure is used as anode material for fabricating symmetric two-electrode supercapacitor systems. Moreover, the LaFeO3/g-C3N4@RGOH materials display magnificent cyclic stability of 82% for 5000 cycles at a current density of 10 A g − 1, which claims the new material progress in the energy field.
... The average crystallite size calculations by Debye-Scherrer's formula reveal a minimum crystallite size of 80.9 nm for AMPG2 than the other AMPGs [28]. The crystallite sizes of AMP, AMPG1, AMPG3 and AMPG4, respectively, are 89.0 nm, 97.7 nm, 84.5 nm and 97.6 nm [29,30]. ...
... The chemical states of the elements present in the AMPG2 sample are investigated by performing X-ray photoelectron spectroscopy (XPS). In Fig. 4a, the deconvoluted peak position at a binding energy (BE) of 284.2 eV is resolved for the sp 2 hybridized carbon atoms responsible for the nonoxygenated rings in the reduced graphene oxide (C-C and C=C groups) [28,41]. The combination of carbon-oxygen groups, namely epoxy (C-O)/hydroxyl (C-OH), is deconvoluted at a BE of 286.03 eV. ...
In the present study, as-synthesized pure ammonium manganese phosphate hydrate (AMP) is infused with rGOx variate (Xmg = 25, 50, 75, 100) and four different hybrid composites (AMPG1, AMPG2, AMPG3 and AMPG4) have been synthesized by facile microwave route. The XRD results show two prominent peaks, one at 2θ = 10.04° (010) and other at 2θ = 31.3° (200) in all AMPGs. The Debye–Scherrer’s calculations show minimum crystallite size only for AMPG2 (80.9 nm). The Raman study confirms the rGO presence in AMPG2. The XPS confirms the existence of Mn as Mn²⁺ in AMPG2. The SEM/HR-TEM shows a cluster of uniform rectangular flake slabs only for AMPG2. The CV reveals that pure AMP and AMPGs exhibit pseudocapacitance. The GCD shows higher specific capacitance of 705 F g⁻¹ at a current density of 1 A g⁻¹ for AMPG2. The AMPG2//rGO hybrid device at 3 M aqueous H2SO4 shows higher specific capacitance of 336 F g⁻¹ at 1 A g⁻¹ in the potential window 0–1.8 volts, and even after 5000 cycles, the device retained 80% of its specific capacitance. The reason may be due to mapping of optimal concentration of rGO (50 mg) with PO43-\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${\text{PO}}_{4}^{3 - }$$\end{document} and NH4+\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${\text{NH}}_{4}^{ + }$$\end{document} of AMP by forming strong coordination for better activation sites for ion mobility. The energy and power densities of AMPG2//rGO device are 151 Wh kg⁻¹ and 448 W kg⁻¹ at 1 A g⁻¹, which are reported for the first time for high-energy supercapacitor applications.
Graphic abstract
Transition metal phosphate based materials is being used for energy storage because of P–O covalent bond which facilitates more storage compared to other transition metals and this covalent bond enhanced the electrochemical performance for supercapacitor applications. Pure magnesium phosphate (Mg 3 (PO 4 ) 2 ) were synthesized via microwave synthesis as the composite varies with rGO (MgPO-XrGO) X =25,50,75,100mg . The prepared composite materials were examined employing XRD, Raman, FT-IR, SEM and XPS studies. Electrochemical studies (CV, EIS, GCD) of three electrode system for the prepared electrodes were performed using Biologic SP-150 with 2M (H 2 SO 4 ) as electrolyte. From the XRD results, triclinic structured MgPO was confirmed (JCPDS card #35–0329) and rGO has enhanced the crystallinity of MgPO composite. From Raman analyses, the well graphitization nature of rGO in composite MgPO was identified and from XPS analysis chemical composition of the elements was analyzed. The FT-IR fundamental modes of vibrations of PO 4 3 − ${\text{PO}}_{4}^{3-}$ ( γ 1 , γ 3 , γ 4 ) were obtained. The electrochemical analysis of the prepared material such as pure and composite materials showed better performance. The high specific capacitance was obtained for MgPO-50rGO because MgPO has high coordination with rGO. As Mg ²⁺ oxidation state has high chemical reactivity compared to other earth metals and other advantage is P–O covalent bond that enhanced the performance of the electrode. By facilitating these advantages, rGO is included as composite to develop the electrode to favor the practical applications. By using the optimum level rGO composite with MgPO 4 -50rGO a better new candidate was successfully developed for supercapacitor applications. The fabricated MgPO-50rGO//Activate carbon full cell set up exhibited the specific capacitance 61 Fg ⁻¹ at 1 Ag ⁻¹ , 21.7 Wh kg ⁻¹ energy density and 790.0 W kg ⁻¹ power densities and explored outstanding capacitive retention in 2 electrode full cell setup cyclic stability of 99.1 % over the 5000 cycles.
