Electrochemical Performance For Supercapacitors Research Articles

Fabrication and characterization of Sb2O3-MoS2 nanocomposites for high performance supercapacitor applications.

Binary nanocomposite-based electrodes have been studied extensively in recent times owing to their multiple oxidation states, excellent physico-chemical features, and combined morphology, which are suitable for increasing the electrochemical performance of supercapacitors. The present work deals with Sb2O3-MoS2 NCs electrode for supercapacitor applications. The XRD, Raman, SEM, EDX, HRTEM, SAED and XPS characterizations have been studied to analyze the phase formation, vibrational modes, morphology, elemental composition and binding energies of the prepared Sb2O3-MoS2 NCs electrode material, as well as their electrochemical measurements such as CV, GCD, and EIS have been analyzed. The developed Sb2O3-MoS2 NCs electrode provides a high specific capacitance of 454.3 F/g at the current density of 1 A/g. Further, the hybrid supercapacitor device has been constructed which shows 104.04 F/g of specific capacitance at 2 A/g and manifests a good energy density of 24.42 Wh/kg at a power density of 1299.89 W/kg. Additionally, the hybrid device Sb2O3-MoS2//AC exhibits a good capacitive retention of 90.6% and a coulombic efficiency of 100.45% at 10 A/g over 8000 cycles.

Integrated construction improving electrochemical performance of loadable supercapacitors based on porous cement-based solid electrolytes

Emerging integrated loadable supercapacitors (ILSs) are prominent candidates for zero-energy buildings with both load-bearing/energy storage capacity. However, the development of solid electrolytes with good mechanical and electrochemical performance remains a major challenge in realizing an integrated electro-mechanical system. Herein, the porous cement-based solid electrolytes (PCSEs) with the combined characteristics of high ionic conductivity and certain compressive strength are successfully developed by a facile “killing two birds with one stone” chemical foaming strategy using potassium iodide (KI) as the reaction modifier, and hydrogen peroxide (H2O2) and Portland cement as the foaming agent and substrate, respectively. The KI is introduced to balance the paradoxical relationship between ionic conductivity and compressive strength while improving the pseudocapacitance of the electrode. Benefiting from these intriguing integrated characteristics, the symmetrical ILS assembled with PCSE and reduced graphene oxide (rGO) electrodes can deliver a maximal energy density of 21.6 Wh kg−1 and a power density of 1106.2 W kg−1. Meanwhile, the ILS exhibits stable electrochemical behavior when withstanding external forces, which is a rarely studied aspect in other reports. Our results provide the basis for simple and universally applicable systems that fulfill the requirements of structural energy storage for civil engineering.

All colloidal supercapattery: colloid@carbon cloth electrodes meet "water‐in‐salt" electrolyte

The pursuit of excellent electrochemical performance, nonflammability and environmental friendliness of aqueous batteries and supercapacitors has driven efforts to find high‐energy yet reliable electrode materials and electrolyte solutions. Here, all colloidal supercapattery are developed using high‐concentration "water‐in‐salt" electrolytes (LiTFSI‐KOH) and pseudocapacitive colloid@carbon cloth as both positive and negative electrodes, which showed merits of batteries and supercapacitors. Ni/Co‐colloid @carbon cloth positive and Fe‐colloid @carbon cloth negative electrodes can be synthesized by in situ electrochemical reaction. The maximum operating voltage of an aqueous colloidal supercapattery is 1.8 V, and the energy density can reach 73.98 Wh kg−1 at a power density of 1799.5 W kg‐1. The specific capacitance of the aqueous colloidal supercapattery still maintains 74.3% of the initial after 2000 cycles of charge/discharge measurement. The combination of quasi ion colloidal materials and "water‐in‐salt" electrolyte pave a profound way to achieve high energy and power ability simultaneously at the supercapattery device.

The Hydrothermal-Assisted Approach Improves the Photocatalytic and Energy Storage Performance of Novel CuSe-TiO2-GO Composite.

This study reports a novel CuSe-TiO2-GO composite, synthesized by a facile hydrothermal method at a controlled temperature, and investigates its electrochemical performance for supercapacitors (SCs) and photocatalytic behavior for degrading methylene blue (MB) dye. The compositional phase structure and chemical bond interaction were thoroughly investigated. The as-fabricated pristine, binary, and ternary composites underwent comprehensive characterization employing spectroscopic techniques and electrochemical analysis. Compared with pure and binary compounds (CuSe, TiO2, and binary CuSe-TiO2 composites), the ternary CuSe-TiO2-GO composites demonstrated a high degradation efficiency while degrading MB in less than just 80 min (240 min, 100 min, and 140 min, respectively). The photocatalytic activity of the ternary CuSe-TiO2-GO composites is enhanced due to the highly positive conduction band of CuSe, leading to the quick excitation of electrons to the conduction band of CuSe. Subsequently, graphene oxide (GO) left holes on the photocatalyst surface for MB, as GO assisted the photoexcited electron-hole pairs, resulting in enhanced photocatalytic performance. The CuSe-TiO2-GO electrode for the supercapacitor indicates a 310.6 F/g and 135.2 F/g capacitance when the discharge current upsurges from 1 to 12 A/g. The good photocatalytic and energy storage performance is due to the smaller charge transfer resistance, which promotes efficient separation of electron-hole pairs.

N, S-codoped porous biochar derived from bagasse-based polycondensate for high-performance CO2 capture and supercapacitor

The utilization of in-situ heteroatom doping and carbonization techniques to produce porous biochar from waste biomass sources has the potential to significantly enhance electrochemical and CO2 adsorption performance of supercapacitors. In this work, an initiative N, S-codoped biochar was prepared through carbonation and KOH-activated pyrolysis of bagasse-based polycondensate precursors, which were synthesized using sugarcane bagasse as a carbon source, 3-amino-5-methio-1,2,4-triazole as a nitrogen and sulfur source and triglycidyl isocyanurate (TGIC) as a cross-linker, for efficient CO2 capture and energy storage. Through comprehensive material characterization and testing of the electrochemical and CO2 adsorption performance of the N,S-codoped bagasse-based porous biochar (NSBPB), the results demonstrated that the mesoporeous structure and the N, S-codoping displayed a significant synergistic effect on electrochemical and CO2 adsorption properties. The optimized NSBPB-600-2 displayed a CO2 adsorption capacity of 3.76 mmol g−1, and no significant decrease in adsorption capacity was observed over consecutive ten cycles. Moreover, the NSBPB-600-2 electrode delivered a specific capacitance of 217F g−1, and the NSBPB-600-2 symmetric supercapacitor exhibited a energy density of 13 Wh·kg−1. This approach invoving in-situ heteroatom doping of porous carbon materials using clean biomass carbon sources not only offers the advantages of simplicity, environmental friendliness and low cost, but also holds great potential for applications in CO2 capture and separation, as well as in supercapacitors.

Design a novel mixed-ligand Ni-MOF/MWCNT nanocomposite to enhance the electrochemical performance of supercapacitors

Metal-organic frameworks (MOFs) have garnered considerable interest for supercapacitors as electrode materials. Although MOFs possess large pore sizes and high specific surface areas, most MOFs face major challenges due to their inferior stability and low electronic conductivity. In this study, we synthesized Ni-MOF/MWCNT nanocomposite using a mixed-ligand approach through hydrothermal method to provide more redox reaction sites, facilitate ion diffusion, increase the stability, and electronic conductivity of the electrode. Benzoic acid (BA) has partially replaced Benzene-1,3,5-tricarboxylic acid (BTC). BTC has been used to shape Ni-MOF nanosheets into flower-like microspheres, which can reduce the electron/ion diffusion path. The introduction of BA and combination of MWCNT and Ni-MOF result in high electric conductivity. Furthermore, the combination of two organic ligands, and the synergistic effect of MWCNTs and Ni-based MOFs lead to excellent electrochemical performance. The prepared Ni-MOF/MWCNT nanocomposite shows an outstanding capacitance of 900Fg-1 at 0.5Ag-1 and excellent cycling stability with 82% capacity etention over 1000 cycles. This study presents an innovative strategy for enhancing energy storage performance.

Electrochemical Performance of Supercapacitor Using Plasticised Corn Starch Polymer Electrolyte Incorporated with Lithium Iodide

An electrical double-layer capacitor (EDLC) is a supercapacitor type that offers higher energy density and capacitance than an electrolytic capacitor. EDLC bridges the energy or power gap between the batteries, fuel cells, and dielectric capacitors. Most EDLCs are fabricated using electrolytic solutions, many of which are highly corrosive, leading to heavy, bulky, and leaky devices. This research assembled an EDLC employing a plasticised solid polymer electrolyte based on lithium iodide (LiI) doped corn starch. Glycerol was used as the plasticiser. The fabricated EDLC was characterised using cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and galvanostatic charge-discharge (GCD) techniques. The specific capacitance obtained from EIS was 1.74 F g–1. By analysing the Nyquist plot obtained from EIS, charge transfer resistance (Rct) and equivalent series resistance (ESR) were determined. CV of the EDLC was carried out at various sweep rates. The highest specific capacitance of 4.66 F g–1 was obtained at a 50 mV s–1 sweep rate. The EDLC was charged and discharged ten times at 1 mA constant current. From GCD, the specific capacitance was found to be in the 4.36 – 5.57 F g-1 range. From these results, starch-LiI-glycerol showed potential as a candidate for electrolyte material for energy device applications.Keywords: Electrolyte, electrical double-layer capacitor, glycerol, lithium iodide, solid polymer, starch, specific capacitance

Exploring the effect of morphology on electrochemical performance of nickel and cobalt metal-organic frameworks and their derivatives for supercapacitor and hydrogen evolution

This study explores the novel approach of investigating the use of binder-free nickel and cobalt metal-organic frameworks and their metal oxide derivatives in 1D, 2D, and 3D morphologies on Ni foam for applications in supercapacitors and hydrogen evolution. This research work involves changing parameters like precursor concentration, organic linkers, and reaction time, leading to the formation of stable one-, two-, and three-dimensional NiO and Co3O4 nanostructures. The morphologies of pristine MOFs and their corresponding oxides were comprehensively verified through FESEM analysis. Significantly, the materials with two-dimensional growth exhibited superior electrochemical performance in supercapacitors and good electrocatalytic performance in hydrogen evolution reaction when compared to their one-dimensional and three-dimensional counterparts. Among them, 2D NiO demonstrated exceptional performance as a supercapacitor electrode, with a specific capacity of 688.13 C g−1 (1376.26 F g−1) at 1 A g−1, surpassing 1D and 3D NiO nanostructures. It also demonstrated good stability by retaining 93.1 % of its initial capacity after 5000 cycles at 10 A g−1. The assembled asymmetric supercapacitor (ASC) achieved a high energy density of 65.27 Wh kg−1 at 375 W kg−1, maintaining 33.18 Wh kg−1 even at 7500 W kg−1. It also maintained 87.8 % retention of its initial capacity up to 5000 cycles at 10 A g−1. Furthermore, when tested for HER, all oxides exhibited better performances with specifically 2D NiO exhibiting good catalytic performance, reaching 10 mA cm−2 at a low overpotential of 129 mV (vs. RHE) and displaying remarkable stability over 24 h. This study upholds the superiority of two-dimensional sheet-like structures with interconnected network of nanoparticles in electrochemical and electrocatalytic performance compared to one-dimensional rod-like and three-dimensional pyramid-like structures.

Preparation of Ni Nanowires Covalent Organic Framework Composites with High Electrochemical Stability and Supercapacitor Performance

Preparation of Ni Nanowires Covalent Organic Framework Composites with High Electrochemical Stability and Supercapacitor Performance

In Situ Self-Assembly of Nitrogen-Doped 3D Flower-like Hierarchical Porous Carbon and Its Application for Supercapacitors.

The hierarchical porous carbon-based materials derived from biomass are beneficial for the enhancement of electrochemical performances in supercapacitors. Herein, we report the fabrication of nitrogen-doped 3D flower-like hierarchical porous carbon (NPC) assembled by nanosheets using a mixture of urea, ZnCl2, and starch via a low-temperature hydrothermal reaction and high-temperature carbonization process. As a consequence, the optimized mass ratio for the mixture is 2:2:2 and the temperature is 700 °C. The NPC structures are capable of electron transport and ion diffusion owing to their high specific surface area (1498.4 m2 g-1) and rich heteroatoms. Thereby, the resultant NPC electrodes display excellent capacitive performance, with a high specific capacitance of 249.7 F g-1 at 1.0 A g-1 and good cycling stability. Remarkably, this implies a superior energy density of 42.98 Wh kg-1 with a power density of 7500 W kg-1 in organic electrolyte for the symmetrical supercapacitor. This result verifies the good performance of as-synthesized carbon materials in capacitive energy storage applications, which is inseparable from the hierarchical porous features of the materials.

Electrodeposition of polyaniline on reduced graphene oxide/cotton yarn with tunable electrochemical performance for flexible textile supercapacitors

Graphene/cotton fibers show significant promise in wearable energy storage due to their low cost, porous structure, and exceptional integration ability into wearable systems. However, the eco-unfriendly reductants and standalone electric double-layer capacitor hindered their application. Herein, a green and rapid hydrothermal-electrodeposition method was proposed to fabricate polyaniline (PANI) decorated reduced graphene oxide (rGO)/cotton yarns without using any chemical reductants and oxidants. The PANI/rGO/cotton (PRC) yarn exhibited porous conductive network, structural controllability, and mechanical flexibility. Additionally, the PRC yarn electrode delivers a fast electron transport and ion migration, synergistic energy storage contribution, and a controllable capacitance (up to 81.2 mF cm−1 at 0.2 mA cm−1). The assembled yarn supercapacitor shows a good capacitance (19.8 mF cm−1 at 0.08 mA cm−1), excellent energy-power density (2.7 μWh cm−1 at 40 μW cm−1), and great capacitance retention. This green fabrication of PRC yarns brings new insights into the development of wearable energy storage.

The Conversion of Li2SnO3 Li-Ion Hybrid Supercapacitors from Pastes Containing LiCl-SnCl2 Liquid Precursors Using an Atmospheric-Pressure Plasma Jet

We fabricate lithium tin-based oxide Li2SnO3 on carbon cloth from a gel-state precursor containing LiCl and SnCl2·2H2O using a nitrogen atmospheric-pressure plasma jet (APPJ). APPJ treatment provides both a high-temperature environment for the conversion of precursor into Li2SnO3 and nitrogen plasma reactive species for electrode surface modification. Here, the best electrochemical performance for the Li2SnO3 Li-ion hybrid supercapacitors (Li–HSCs) is achieved with 480 s of APPJ processing. The areal capacity of the 480 s APPJ-processed Li2SnO3 Li–HSCs reached 46.113 mC/cm2. The results indicate that APPJ is an effective tool for the rapid conversion processing of Li2SnO3 electrodes for Li–HSCs.

Enhancing sp3 content in diamond-like carbon thin film electrodes by pulsed laser annealing for durable charge storage performance

In this work, diamond-like carbon (DLC) thin film electrodes were grown on Si substrate by pulsed laser deposition (PLD) technique, and the implication of pulsed laser annealing (PLA) treatment on their electrochemical supercapacitor performance was examined by three electrode systems in 1 M Na2SO4 electrolyte solutions. The SEM micrographs exhibit a sheet-like wrinkled surface of DLC film on Si which later transformed into tiny hierarchical heap-like structures with enhanced surface roughness. The Raman spectra confirm signature of the D and G peaks of pristine DLC film at ∼1352 cm−1 (1356 cm−1 after PLA) and 1591 cm−1 (1589 cm−1 after PLA), and appearance of minor T2g (diamond) (1332 cm−1) peaks with an increment of the sp3 content after PLA treatment. The X-ray photoelectron spectroscopy (XPS) spectra were deconvoluted into three different contributions CC (sp2), CC (sp3), and CO, and their sp3 percentages were estimated ∼48.9 %, and 64.7 % before and after annealing. The area under cyclic voltammetry (CV) curve and galvanostatic charging discharging (GCD) performance of PLA-treated DLC film were improved and the highest areal-specific capacitance was obtained to be ∼48.25 mF/cm2 for scan rate of 5 mV/s and 36.01 mF/cm2 for current density of 2 mA/cm2, respectively. Excellent charging discharging cyclic stability of PLA treated electrode was observed over 5000 cycles, and Coulombic efficiency and capacitance retention were determined to be ∼93.5 % and ∼ 97.3 %, respectively. The electrochemical impedance spectroscopy (EIS) was performed to obtain the Nyquist plot (Z′vs.Z′′) of both electrodes before and after the stability test, and a small degradation in impedance was observed. The Nyquist plots were fitted with the well-known Randles equivalent circuit model Rs(Cdl(RctZw)) and substantial curtailment of Warburg resistance (Zw) in PLA-induced DLC electrode signifies the dominance of the diffusion-controlled region in the charging-discharging process. Minor changes in the Nyquist plot before and after the stability test manifest the enduring charge kinetics of both electrodes and PLA-treated DLC exhibits better cyclic stability. PLA techniques have a great impact on upgrading the areal-specific capacitance, capacitance retention with high Coulombic efficiency, and stability with negligible impedance loss of the DLC film electrodes.

Palladium enhanced electrochemical supercapacitive performance of chromium oxide thin films synthesized by sputtering process

Recently, the use of transition metal oxide electrodes for supercapacitor applications has increased due to the possibility of variable mixed valence states. The present study has established the use of Pd-Cr2O3 composite thin films as a working electrode for high-performance supercapacitors. The reactive dc magnetron co-sputtering method has been used for the fabrication of thin film of Cr2O3 and Pd-Cr2O3 on SS-304 substrate. X-ray diffraction and X-ray photoemission spectroscopy techniques were used to examine the surface chemistry and phase purity of chromium oxide and Pd-Cr2O3 composite thin films. The incorporation of Pd in Cr2O3 delivers a drastic change in the surface morphology. Due to the modified morphology and electronic properties, a noticeable improvement in the electrochemical properties of Pd-Cr2O3 electrode is observed. The obtained value of specific capacitance for this electrode is 401 Fg−1 at 0.1 mAcm−2 scan rate and within the potential window range 0 to +1.2 V. This value of specific capacitance is almost twice in comparison to the Cr2O3 based electrode. The Pd-Cr2O3 composite thin film shows a good cycle retention capability of 8000 cycles with 87.5 % retention. The obtained value of energy density and power density for Pd-Cr2O3 electrode was 80.2 Whkg−1 and 3.23 kWkg−1, respectively at 0.1 mAcm−2. Consequently, this composite material electrode can be seen as a promising advancement for electrodes in supercapacitor devices.

Home-made chemical vapor deposition-based synthesis of binder-free nanostructured magnesium-molybdenum-sulfide electrode materials for supercapacitor application

Molybdenum disulfides (MoS2) is considered as promising electrode materials (E-M) for high electrochemical performance (ECP) of lithium-ion batteries and supercapacitors due to their layered nanostructures. Herein, MoS2, MgS and hetrostructure MgS/MoS2 E-Ms comprising of nano-particles/sheets/needles like structures are synthesized on Nickel foam (Ni–F) by a simple home-made chemical vapor deposition (CVD) technique. The XRD analysis confirmed the formation of MoS2, MgS and MgS/MoS2 polycrystalline E-Ms growing along different directions. The FESEM analysis is confirmed that the addition of MgS layer over the surface of MoS2 change the surafce morphology from nano-particles to nano-needles. The change in structural and microstructural features is indicated the appearance of defects, micro-strain and dislocations density which are fruitful for excellent ECP. The cyclic voltammetry analysis is indicated the pseudocapacitive nature of the synthesized E-Ms. The maximum specific capacitance values for MoS2/Ni–F, MgS/Ni–F and MgS/MoS2/Ni–F E-Ms are 1273, 1688 and 3934 F/g at 1 A/g respectively. Moreover, the addition of MgS layer over MoS2/Ni–F is revealed the excellent cyclic stability of 98.76 % at current density of 10 A/g after 4000 cycles, energy density values are ranged from 79 to 136 W h/kg with homologous power density of 250–2500 W/kg and very small charge transfer resistance. The simulations of Power's Law and Dunn's model is confirmed that the excellent ECP is due to both capacitive and diffusive controlled contributions of heterostructured MgS/MoS2/Ni–F E-Ms. Additionally, MgS/MoS2/Ni–F E-Ms have both battery and pseudocapacitive nature due to unique nano-needles like morphology. The excellent electrochemical properties of MgS/MoS2/Ni–F E-Ms substantiate their potential applications in portable energy storage devices.

Pore size, conductivity and surface area effects of rGO/ZnO/PTh hybrid nanocomposite for supercapacitors

This paper presents an easy and low-cost synthesis of reduced graphene oxide (rGO) and Zinc oxide (ZnO) as binary nanocomposite (rGO/ZnO) and rGO, ZnO and polythiophene (PTh) as ternary hybrid nanocomposite (rGO/ZnO/PTh). Firstly, graphene oxide (GO) was synthesized from modified Hummers method. And it was reduced by microwave-assisted method to form as reduced graphene oxide (rGO). Polythiophene (PTh) was chemically synthesized to comparison with nanocomposites. Secondly, binary nanocomposite of rGO/ZnO were synthesized by probe-sonication method. Thirdly, rGO/ZnO/PTh hybrid nanocomposite was chemically synthesized using FeCl3 as an oxidant. All these materials were examined by many different techniques, such as FTIR-ATR, SEM-EDX, TGA-DTA, BET, Four-point probe analysis, cyclic voltammetry (CV), galvanostatic charge-discharge (GCD), and electrochemical impedance spectroscopy (EIS) analysis. The average pore width, conductivity and specific capacitance values were comparatively investigated to understand these effects on electrochemical performances of supercapacitor devices.The highest specific capacitance (Csp) was obtained as Csp = 430 F/g for rGO/ZnO nanocomposite at a scan rate of 2 mV/s. Moreover, it also shows a good charge/discharge performance (up to 1000 cycles) with 98.43 % capacitance retention at a scan rate of 100 mV/s by CV method. However, GCD and EIS methods have showed the highest specific capacitances as Csp = 85.6 F/g at 10 A/g, and Csp = 25.8 F/g for both hybrid rGO/ZnO/PTh nanocomposites, respectively. In addition, a new equivalent circuit model [R1(C1(Rct(C2R2)))] was suggested to interpret the EIS data for supercapacitor devices. As a results, both binary and ternary nanocomposites may be recognized as electrode materials with three different methods (CV, GCD and EIS) in supercapacitor applications.

Metal oxide-based nanocomposites as advanced electrode materials for enhancing electrochemical performance of Supercapacitors: A comprehensive review

In recent years, the escalating use of nonrenewable fossil fuels has emerged as a significant threat to global sustainability, prompting the need for renewable, cost-effective, and eco-friendly energy storage solutions. Supercapacitors (SCs) are notable for their high power density (PD), cycle stability, and swift charge/discharge rates, although they fall short in energy density (ED) compared to traditional batteries. The performance of SCs is greatly influenced by the electrode materials used, highlighting the importance of material innovation in tackling the challenges posed by increasing fossil fuel consumption. Transition metal oxides (TMOs), known for their redox activity in energy storage, have been thoroughly investigated for their exceptional specific capacitance, which ranges from 100 to 2000F g−1, surpassing that of electrical double-layer capacitors (EDLCs). TMOs such as ruthenium oxide (RuO2), manganese oxide (MnO2), nickel oxide (NiO), cobalt oxide (Co3O4), tin oxide (SnO2), zinc oxide (ZnO), tungsten oxide (WO3), and vanadium pentoxide (V2O5) are widely researched for their high theoretical capacitance, affordability, and longevity. This review emphasizes the groundbreaking potential of metal oxide nanocomposites (NCs) formed by combining them with graphene, carbon nanotubes (CNTs), and polymers, leading to synergistic enhancements in electrical conductivity, surface area, and charge storage capacity. This thorough review not only presents an in-depth analysis of current research but also sheds light on potential future developments, contributing to the ongoing progress in the field of advanced electrode materials for energy storage.

Synthesis and characterization of SnO2-La2O3 for electrochemical supercapacitor performance in redox additive electrolyte

Synthesis and characterization of SnO2-La2O3 for electrochemical supercapacitor performance in redox additive electrolyte

RGO‐Modified CoWO4 Nanoparticles as New High‐Performance Electrode Materials with Enhanced Electrochemical Performances for Supercapacitors

A facile one‐pot hydrothermal method is provided for synthesis of the reduced graphene oxide‐cobalt tungstate (rGO@CoWO4) nanocomposites with the enhanced electrochemical performances for supercapacitors (SCs). The resulting nanocomposites are comprised of CoWO4 nanospheres that are well anchored on graphene sheets by in situ reducing. The BET‐specific surface area of CoWO4, rGO@CoWO4 nanocomposites are 101 and 167 m2 g−1, respectively. The electrochemical evaluations are carried out in a 1 M KOH solution as the electrolyte. The hybrid electrode shows excellent specific capacitance of 1145 F g−1 at a current density of 1 A g−1 with superior rate capability and satisfactory cycling stability (97.2% capacitance preserved after 10 000 cycles). The good electrochemical performance can be attributed to the increased electrical conductivity and the creation of new active sites due to the synergetic effect of rGO and CoWO4 nanospheres. Moreover, the cyclic stability tests demonstrat capacitance retention of about 97.2% after 10 000 cycles, suggesting the potential application of rGO@CoWO4 nanocomposites in energy storage devices. The asymmetric SCs assembled with rGO@CoWO4 and activated carbon exhibit high energy density (39.1 Wh kg−1) and power density (631.2 W kg−1 at 1 A g−1), with remarkable cycle life (96.7% over 10 000 cycles) while still maintaining 24.5 Wh kg−1 at an even higher power density of 5098 W kg−1. The above results indicate that the hybrid rGO@CoWO4 electrodes synthesized by this approach would be a promising candidate for practical application of high‐performance SCs.

Enhanced dye-sensitized solar cell performance and electrochemical capacitive behavior of bi-functional ZnO/NiO/Co3O4 ternary nanocomposite prepared by chemical co-precipitation method

Increasing prerequisites for sustainable energy storage and conversion technologies have necessitated the exploration of advanced materials with improved properties. Here, we present the synthesis and characterization of ZnO nanoparticles (NPs), ZnO/NiO, ZnO/Co3O4 and ZnO/NiO/Co3O4 NCs as promising bi-functional materials for dye-sensitized solar cell (DSSC) and electrochemical energy storage applications. A facile chemical co-precipitation approach was followed to synthesize pure ZnO NPs, ZnO/NiO, ZnO/Co3O4 and ZnO/NiO/Co3O4 NCs. The structural and morphological analyses revealed the successful integration of ZnO, NiO, and Co3O4 NPs and also the formation of well-defined core-shell and homogenous nanocomposite structures. The XRD and HRTEM analyses confirmed the crystalline nature and nanoscale morphology of synthesized materials, respectively. The photovoltaic performance of DSSC fabricated using ternary ZnO/NiO/Co3O4 NC photoanode showed optimum dye-loading and best solar to electrical energy conversion efficiency with Jsc of 11.29 mA cm−2 and ƞ of 4.66%, which was considerably higher than the DSSC fabricated using pure ZnO NPs photoanode (ƞ = 2.01%). The increment in photocurrent density (Jsc) could be ascribed to the perfect band alignment of NiO and Co3O4 NPs in the ternary NC. Further, the ZnO/NiO/Co3O4 NC photoanode integrated DSSC disclosed 97% retainment in energy conversion efficiency even after 10 days of operation. The electrochemical performance of supercapacitor fabricated using ternary ZnO/NiO/Co3O4 NC showed high specific capacitance of 534.7 Fg−1 at 1 Ag−1 with favourable rate ability (∼52% at 16 Ag−1), good cyclic stability (91.07%) and low internal resistance. Moreover, the ZnO/NiO/Co3O4 NC at a current density of 2 Ag−1 exhibited a significantly high capacitance value of 463.1 Fg−1, which was 1.93, 1.58 and 1.22 times greater than ZnO NPs, ZnO/Co3O4 NC and ZnO/NiO NC, respectively.