Electrode Materials For Supercapacitors Research Articles

Activated carbon-supported LaNiO3 perovskite nanocomposite supercapacitor electrode material exhibiting superior power density and life cycle

Activated carbon-supported LaNiO3 perovskite nanocomposite supercapacitor electrode material exhibiting superior power density and life cycle

PEDOT: PSS Doped Activated Biochar as a Novel Composite Material for Photocatalytic and Efficient Energy Storage Application

Herein, we report the synthesis of activated biochar from green algae and the effect of its doping on the structural, photocatalytic, and energy storage properties of PEDOT-PSS. The morphology of pure and doped samples was investigated with Fourier Transform Infrared Spectroscopy (FTIR), Atomic Force Microscopy (AFM), Brunauer–Emmett–Teller (BET) analysis, and thermogravimetric analysis (TGA). AFM results for PEDOT-PSS@6wt.% of BC indicate that the calculated average peak height, particle size, and roughness were 283 nm, 136 nm, and 71 nm, respectively. Adding biochar to PEDOT-PSS significantly improved the thermal stability of PEDOT-PSS up to 550 °C. The novel photocatalyst PEDOT-PSS@6wt.% BC improved photocatalytic performance by approximately 17% in Methylene Blue (MB) dye removal. The electrochemical performance in terms of supercapacitors for the synthesized samples was investigated using cyclic voltammetry (CV), galvanostatic charge–discharge (GCD), specific capacitance, stability, and electrochemical impedance spectra (EIS). PEDOT-PSS@6wt.% of BC as a novel electrode material in supercapacitors exhibits an initial specific capacitance of 1300 Fg−1. Moreover, the PEDOT-PSS@6wt.% of BC electrode shows excellent stability up to 1000 cycles of operation. The EIS studies suggest the presence of charge transfer resistance. Considering the economical biosynthesis and multifunctional features, the PEDOT-PSS@6wt.% of BC could potentially be used as a photocatalyst to remove organic dyes and supercapacitors in energy storage applications.

Construction of hierarchical and core-shell structured Co3O4@MnO2@NiO nanoarrays as binder-free electrodes for high-performance asymmetric supercapacitors

Remarkable specific capacity and excellent cycle stability of the electrode materials are vital prerequisites for their practical applications. Transition metal oxide-based materials have been extensively explored and employed as electrode materials for asymmetric supercapacitors. However, the actual specific capacitances of these materials are still far lower than their theoretically predicted values. Thus, it is essential to design transition metal oxide with novel structures in order to maximize their specific capacity and cycle stability. Herein, we constructs hierarchical and core-shell structured Co3O4@MnO2@NiO arrays on nickel foam (Co3O4@MnO2@NiO/NF) through a three-step hydrothermal-annealing process, and use them as a direct binder-free electrode for pseudocapacitors. The as-prepared layered hierarchical Co3O4@MnO2@NiO/NF electrode exhibits an impressive specific capacitance of 6.42 F cm−2 (2054 F g−1) at 1 mA cm−2 in a three-electrode configuration, which is largely because of the synergistic effect among Co3O4, MnO2 and NiO. Furthermore, the 3D nanoarray structure can provides a larger specific surface area, a rapid diffusion path, and more active sites that allow to achieve improved electrochemical performance. In addition, the assembled Co3O4@MnO2@NiO/NF//AC/NF ASC all-solid-state asymmetric supercapacitor (ASC) displays a remarkable energy density (30.7 Wh kg−1 at 400.4 W kg−1), demonstrating that this all-solid-state ASC owns considerable potential for practical applications in such high-performance energy storage devices.

Microporous tungsten oxide spheres coupled with Ti3C2Txnanosheets for high-volumetric capacitance supercapacitors.

In the contemporary landscape of technological advancements, the burgeoning demand for portable electronics and flexible wearable devices has necessitated the development of energy storage systems with superior volumetric performance. Tungsten oxide (WO3), known for its high density and theoretical capacitance, is a promising electrode material for supercapacitors. However, low conductivity and poor cycling stability are still the key bottlenecks for its application. Herein, a novel composite comprising hollow porous WO3 spheres (HPWS) derived by template method was electrostatic self-assembled on the surface of the Ti3C2Tx nanosheets. The resulting electrodes exhibited ultra-high volumetric capacitance of 1930 F cm-3 at 1 A g-1 and rate capability of 46% at 50 A g-1, attributed to enhanced ion accessibility from microporous structure and electron transport from conductive network of Ti3C2Tx even at a high packing density of 3.86 g cm-3. Utilizing HPWS/Ti3C2Tx as the negative electrode and porous carbon as the positive electrode, the assembled asymmetric supercapacitor achieved an energy density of 31 Wh kg-1 at a power density of 650 W kg-1 with over 107% capacitance retention after 5000 cycles. This work provides a promising approach for developing next-generation supercapacitors with ultra-high volumetric capacitance.

Hierarchical porous self-supporting graphite carbon electrodes based on the biomimetic structure for supercapacitors

Regulating pore structure, improving conductivity, and reducing the influence of binders are considered important ways to improve the performance of carbon-based electrode materials for supercapacitors. This study successfully prepares a highly graphitized hierarchical porous self-supporting carbon electrode without the need for binders, conductive agents, and current collectors using low-cost and abundant pine wood as the precursor and K2FeO4 as the activator and catalyst. The self-supporting electrode inherits the biological structure of biomass and forms a large number of micro mesopores through activation, showing an excellent 3D interconnected pore structure, and achieves a high degree of graphitization with the ID/IG ratio of being only 0.47. The self-supporting electrode facilitates the effective transport of electrolyte ions and electrons, demonstrating excellent electrochemical performance. It achieves an area specific capacitance of 3.64 F cm−2 under a current density of 5 mA cm−2. Two identical self-supporting electrodes are employed to construct a symmetric supercapacitor. The supercapacitor exhibits an energy density of 148.61 μWh cm−2 at a power density of 1 mW cm−2, with a capacity retention rate of 89.26 % after 10,000 charge-discharge cycles.

Upcycling linear low-density polyethylene waste to turbostratic graphene for high mass loading supercapacitors

Linear low-density polyethylene (LLDPE) waste is difficult to upcycle into more valuable carbon materials because it tends to completely decompose into small molecules during thermal processing. In this work, LLDPE is upcycled into a high quality turbostratic graphene using a pre-treatment step to oxidatively crosslink the polymer with the assistance of solid additives (KCl and K2CO3) that improve crosslinking by increasing the effective surface area of the polymer melt during processing. After this pretreatment step, the crosslinked polymer could then be carbonized and catalytically graphenized between 400–950 °C without decomposition of the polymer feedstock. The LLDPE derived graphene (LLDPE-G) obtained from this process has a Brunauer–Emmett–Teller (BET) specific surface area, up to 1800 m2 g−1 and average Raman ID/IG and I2D/IG ratios of 0.85 and 0.57, respectively, indicating high quality graphene. When used as an electrode material in symmetric supercapacitors, LLDPE-G possesses a specific capacitance up to 175 Fg−1 at a mass loading of 20 mgcm−2, which is two times the commercial requirement, yielding an areal capacitance of 3.5 Fcm−2. Moreover, LLDPE-G exhibits exceptional cycling stability with a capacitance retention of 95.8 % after 100,000 cycles at a current density of 4.0 Ag−1. Additionally, the KCl and K2CO3 solids are recycled and reused over 3 complete reaction cycles to make new LLDPE-G with the material quality and electrocapacitive performance retained and verified after each cycle. Our approach creates new opportunities for upcycling waste LLDPE and other varieties of polyethylene into a higher value graphene used for electrochemical energy storage applications.

Nickel aluminum selenide wrapped by NiCoAl-layered double hydroxide enables a robust structure for supercapacitors

To explore a simple and convenient strategy for the construction of hybrid composites as advanced electrode materials for supercapacitors (SCs), this research realized the construction of nickel − aluminium selenide (NiAlSe)@NiCoAl-layered double hydroxide (NiCoAl-LDH) heterostructure. In-situ hybridization of NiCoAl-LDH nanosheets onto NiAlSe nanoparticles anchored on carbon cloth generates a special core–shell heterostructure, which enhances the exposure of active centers and increases the surface area. The formation of heterogeneous interfaces between NiAlSe and NiCoAl-LDH alters the electronic architecture and accelerates the electron/ion migration. By making full use of the structural benefits and the cooperative effect, the NiAlSe@NiCoAl-LDH composite electrode delivered a large capacitance (Cs) of 1789.2F/g at 1 A/g along with a high retention rate of 94.7 % over 5,000 cycles, which outperforms the bare NiAlSe and NiCoAl-LDH. Meanwhile, the assembled NiAlSe@NiCoAl-LDH hybrid supercapacitor (HSC) attained maximum specific energy (Es) of 71.5 Wh kg−1. This HSC device exhibits superior cyclic durability of 92.1 % after 30,000 cycles. Thereby, this research offers valuable insights into the construction of robust electrode materials for advanced HSC devices.

Self-sulfur doped mesoporous novel carbon electrodes derived from poly-anthraquinone sulfide for high-performance supercapacitors! A comparative study

Carbon materials are suitable electrode candidates in supercapacitors (SCs) because of their availability, well-defined microstructures, and ultrahigh surface areas. Herein, a universal chemical activation method was utilized to obtain activated carbon (C-KOH) from poly-anthraquinone sulfide (PAQS) at 850 °C and reduced activated carbon (C-KOH-H) from C-KOH via a mild hydrogen reduction process at low temperature. The electrochemical performances of the PAQS derived activated carbon electrodes were investigated by assembling electric double-layer capacitors (EDLCs). Electrodes fabricated from C-KOH and C-KOH-H showed 174 and 182.3 F g−1 specific capacitances at 0.5 A g−1 current density, respectively. Whereas their energy densities were 44 and 46 Wh kg−1 at 350 and 423 W kg−1 power densities, respectively. SCs assembled from C-KOH-H showed excellent rate performance, that retained 140 F g−1 even at high current density (20 A g−1), while the one assembled with C-KOH stored 54 F g−1. Furthermore, the C-KOH-H electrode retained 98 % of the initial capacitance at 1 A g−1 over 20,000 continuous cycles. The experimental results revealed that C-KOH-H showed the best electrochemical performance in SCs, which is attributed to the presence of less sulfur and oxygen than C-KOH after the mild reduction. These results prove that PAQS show excellent activation with KOH to produce well-organized porous activated carbons having high specific surface areas, which can be utilized as high-performance electrode materials in SCs.

Facile synthesis of MOF-derived carbon-supported LaZn@C nanocomposite as an efficient electrode material for supercapacitor

MOF-derived transition metal alloys have attracted researcher's interest in energy storage devices due to their vast surface area, high porosity, adjustable pore sizes, ease of modification, abundant active sites, and 3D tunable structure. Metal alloys covered with carbon can stabilize conductivity and ease charge accumulation, and they are suitable candidates for electrode materials for supercapacitor application. In this research article, core-shell LaZn@C nanocomposites were fabricated at different pyrolysis times via a hydrothermal approach. The materials that pyrolysis for two hours have a remarkable specific capacitance of 1024 F g−1 at 1 A g−1 and an impressive energy density of 36.9 Whkg−1. In addition, it has lower Rp∼0.8 Ω and Rs∼0.2 Ω resistance due to the large surface area's high carbon content with cylindrical particles. Moreover, it shows an outstanding retention rate of (94.5 % over 4500 cycles at 1 A g−1). Finally, this research showed the novelty of advanced MOF-derived materials that suggest an efficient electrode material for the electrochemical performance of energy storage devices and supercapacitor applications.

Impact of Nitrogen-Enriched 1T/2H-MoS2/CdS as an Electrode Material for Hybrid Supercapacitor.

Transition metal chalcogenides (TMX) have attracted energy researchers due to their role as high-performance electrode materials for energy storage devices. A facile one-pot hydrothermal technique was adopted to synthesize a molybdenum disulfide/cadmium sulfide (MoS2/CdS) (MCS) composite. The as-prepared samples were subjected to characterization techniques such as XRD, FT-IR, SEM, TEM, and XPS to assess their structure, morphology, and oxidation states. The MoS2/CdS (MCS) composites were prepared in three different ratios of molybdenum and cadmium metals. Among them, the MCS 1:2 (Mo:Cd) ratio showed better electrochemical performance with a high specific capacitance of 1336 F g-1 (high specific capacity of 185.83 mAh g-1) at a specific current of 1 A g-1 for half-cell studies. Later, a hybrid supercapacitor (HSC) device was fabricated with N-doped graphene (NG) as an anode and MCS (1:2) as a cathode, delivering a high specific energy of 34 Wh kg-1 and a specific power of 7500 W kg-1. The high nitrogen content in the MoS2 structure in MCS composites alters the device's performance, where CdS supports the composite structure through its conductivity and encourages the easy accessibility of ions. The device withstands up to 10 000 cycles with a higher Coulombic efficiency of 97% and a capacitance retention of 90.25%. The high-performance NG//MCS (1:2) HSC may be a potential candidate alternative to the existing conventional material.

Synthesis of NiFeCo ternary layered hydroxides and their performances of electrochemical energy storage for solar cells

Ternary layered hydroxide are high-performance electrode materials for supercapacitors. In this study, nickel–iron-cobalt ternary layered hydroxides (NiFeCo-LDHs) with different nickel–iron molar ratios were grown on nickel foam using a one-step hydrothermal method. The effect of nickel–iron molar ratio on the electrochemical performance and morphology of NiFeCo-LDHs was investigated, and the electrode material at a nickel–iron molar ratio of 3:7 had better electrochemical performance up to 7.01F/cm2 (at 1 mA/cm2). The specific capacitance of the assembled hybrid supercapacitor reached 1575.00 mF/cm2 at 3 mA/cm2. In addition, the fabricated all-solid-state hybrid capacitor（742.86 mF/cm2 at 4 mA/cm2) was capable of lighting an LED after charged by a solar cell. The results indicated that the electrochemical performance of NiFeCo-LDHs was affected by the nickel–iron mole ratio and demonstrated the potential application of NiFeCo-LDHs in electrochemical energy storage.

Enhanced electrochemical properties of MnFe2O4/reduced graphene oxide nanocomposite with a potential for supercapacitor application

A single-step solvothermal method has been employed to synthesize MnFe2O4 composite nanoparticles where graphene sheets were incorporated into spherical MnFe2O4 nanoparticles of size ∼57 nm. The synthesized MnFe2O4/reduced graphene oxide (rGO) composite exhibits enhanced electrochemical properties due to its improved porosity, surface area, and conductivity. FTIR, Raman, and XPS studies confirmed the effective reduction of GO and the successful formation of MnFe2O4/rGO composite. When employed as an electrochemical cell electrode, the MnFe2O4/rGO composite showed an enhanced specific capacitance of 253 F g−1, as opposed to 133 F g−1 for the bare nanoparticles. The composite attains significantly improved energy density of 76.06 Wh kg−1 and power density of 7.49 kW kg−1 at current density of 10 A g−1. The unification of 2D graphene and MnFe2O4 nanoparticles yields enhanced electrochemical performance and an outstanding 96 % cyclic stability (after 5000 cycles), which offers a viable approach for developing better supercapacitor electrode materials in the future.

Boosting the capacitive property of binary metal tellurium of MnCoTe/NiFeTe yarn coils-like through surface engineering for high-performance supercapacitors

Improving the performance of electrode materials based on transition metals can significantly push advancements in energy storage devices. In this work, we offer a novel in situ tellurization approach to synthesize brand-new decorated yarn-coils MnCoTe/NiFeTe on a NiF (labeled MCTe/NFTe@NiF) which makes them attractive candidates for electrode materials in hybrid supercapacitors. At first, two consecutive hydrothermal methods were used to create electrode materials MnCo-LDH and MnCo-LDH/NiFe-LDH on nickel foam, respectively. In the following, electrode material MnCo-LDH/NiFe-LDH was subjected to a tellurization process to create MnCoTe/NiFeTe nanostructures. The direct growth strategy of electrode materials on a conductive substrate (NiF) effectively eliminates the need for polymer binder or conductive materials, thereby facilitating the redox process. The MnCoTe/NiFeTe@NiF electrode benefits from the synergistic effects of conductive tellurium and yarn coils-like morphology, resulting in faster electron/ion transport, increased efficiency, and superior electrochemical performance. The MCTe/NFTe@NiF electrode reveals highly desirable electrochemical characteristics, including a specific capacity of 223.36 mA h/g at 1 A/g, and reliable longevity surpassing 10,000 GCD cycles, with maintaining 73.18 % of its initial specific capacity at 30 A/g. We have prepared a hybrid supercapacitor (labeled MCTe/NFTe@NiF(+)//AC@NiF(−)), which utilizes the positive MCTe/NFTe@NiF and the negative AC@NiF electrodes. This hybrid supercapacitor indicated an excellent energy density of 51.55 Wh/kg, a power density of 799.98 W/kg, and showed substantial longevity (92.33 % after 10,000 GCD cycles).

Enhanced charge storage in supercapacitors using carbon nanotubes and N-doped graphene quantum dots-modified (NiMn)Co2O4

The integration of ternary metal oxides into carbon materials is anticipated to significantly boost the electrochemical performance of supercapacitor electrodes. This article synthesized carbon nanotubes (CNT)/(NiMn)Co2O4 composite materials using a straightforward hydrothermal method and subsequently prepared composite thin films of CNT/P-(NiMn)Co2O4@NGQD by phosphating and incorporating nitrogen-doped graphene quantum dots (NGQD). These films served as the functional electrode material for supercapacitors, enhancing their performance capabilities. The specific capacity of CNT/P-(NiMn)Co2O4@NGQD was measured at 2172.0 F g−1 at a current density of 1 A g−1, maintaining a capacitance of 1954.0 F g−1 at 10 A g−1, thus demonstrating excellent rate performance. Electrochemical impedance spectroscopy (EIS) further revealed enhancements in electrolyte flow dynamics and capacitance behavior post-NGQD introduction. The energy density of the composite material reached 94.4 Wh kg−1 at power density of 800 W kg−1, demonstrating superior electrochemical performance. The enhancement in these electrochemical properties is attributed to the high specific surface area and active sites of CNT/P-(NiMn)Co2O4@NGQD films, along with the synergistic effects of NGQD and metal ions facilitating rapid electrons and charge transfer. This work provides new insights into developing high-performance supercapacitors.

Ultra-small one-dimensional rice-like CoMoO4 nanorods as a promising pseudocapacitive electrode for high-performance supercapacitors

The demand for sustainable energy sources increases as society progresses. Supercapacitors possess a long lifespan, have a high power density, are ecologically sound, and have the ability to rapidly charge and discharge. Among the several binary transition metal oxides (BTMOs), metal molybdates (AMoO4) are notable for their significant redox activity, widespread availability, affordability, and small ecological footprint. The exceptional theoretical capacitance of CoMoO4, resulting from the presence of active cobalt ions, distinguishes it from other materials. However, the synthesis of CoMoO4 in nanostructured forms presents a challenge. This study introduces a straightforward one-pot solvothermal technique for producing ultra-small, one-dimensional (1D) rice-like CoMoO4 nanorods. The electrochemical performance of rice-like CoMoO4 nanorods as a supercapacitor electrode material was thoroughly investigated, along with larger CoMoO4 nanorods made using the hydrothermal process for comparison. The structural, morphological, and surface characteristics of the rice-like CoMoO4 nanorods were comprehensively examined. The nanorods, formed like rice grains, exhibited exceptional ability to store electric charge, with an outstanding specific capacitance of 1608.8 F g−1. They demonstrated remarkable cycling stability, retaining 96 % of their capacitance after numerous charge and discharge cycles, indicating their durability and reliability. The nanorods also exhibited a high rate capability of 71 %, which is crucial for applications that demand quick energy delivery. This capability enables the nanorods to maintain considerable capacitance even at higher charge-discharge rates. The results indicate that rice-like CoMoO4 nanorods can be used as a material in supercapacitors.

Graphene oxide from coconut shells for high-performance supercapacitor application

Globally, the demand for materials with high ultrafast charge rates yet slow discharge continues to rise which has resulted in extensive research into supercapacitors. Although the current supercapacitors can meet such demands, the high processing cost coupled with the use of toxic chemicals remains a major concern. In this study, porous graphene oxide (GO) with a unique morphology was synthesized by an improved Tour’s method for supercapacitor application using coconut shells as a precursor. The structure of the synthesized material consists of partially graphitized walls of porous GO. The surface morphology, the defects created in the GO, and the specific surface area of the as-synthesized materials were studied. When evaluated as an electrode material for supercapacitors, a specific capacitance of 173 F/g at 0.5 A/g in 0.5 M Na2SO4 and 139 F/g at 0.5 A/g in 2 M KOH was recorded. Moreover, a high capacitance retention of 99.3% was recorded after 1000 cycles, confirming the good cyclic stability of the synthesized electrode material. The good electrochemical performance can be attributed to the electrode material’s intrinsic structural and compositional superiorities. These findings indicate the potential of using coconut shells as a precursor for the synthesis of high-performance graphene-based supercapacitor electrodes with improved cost-effectiveness and reduced environmental impact.

Anode glow discharge electrolysis synthesis of flower-like α-MnO2 nanospheres: structure, formation mechanism, and supercapacitor performance.

A novel green synthesis strategy-anode glow discharge electrolysis (AGDE) was employed for one-step preparation of a-MnO2 in 2 g L-1 KMnO4 solution, in which Pt needle and carbon rod were regarded as anode and cathode, respectively. The optimal preparation condition is 400 V for 60 min and the power consumption is below 45 W. The XRD, Raman spectra, XPS and EPR proved that a-MnO2 with structural defects (oxygen vacancies) is obtained. SEM and TEM revealed that a-MnO2 shows a flower-like nanospheres with a diameter of 165 nm, which is assembled by many nanosheets. A possible formation mechanism is that the MnO2 is generated via the reduction of MnO4- by H· and eaq- in plasma-liquid interface. Electrochemical test found that MnO2 nanospheres exhibit a specific capacitance of 365 F g-1 at 1 A g-1, and capacity retention of 79.8% after 10,000 cycles at 5 A g-1. The assembled asymmetric supercapacitor shows the maximum energy density of 23.1 Wh kg-1 at power density of 1.89 kW kg-1. In brief, AGDE is a simple, facile and green technique for the synthesis of a-MnO2 without adding extra chemicals, and prepared a-MnO2 can be considered as an excellent candidate of electrode materials for supercapacitor.

In Situ Growth of Nanorod-Shaped Ni,Co-MOF on Mo2CTx MXene Surface to Realize Enhanced Energy Storage for Supercapacitors.

Mo2CTx MXene materials, known for their high conductivity and abundant surface functional groups, are widely utilized as electrode materials in supercapacitors. However, their tendency to stack during electrochemical energy storage hinders their performance. The in situ growth of nanorod-shaped Ni,Co bimetallic metal-organic frameworks (Ni,Co-MOF) on Mo2CTx MXene effectively mitigates this stacking. With their porous structure and high specific surface area, MOFs excel in energy storage, and bimetallic MOFs outperform monometallic ones. The synergy between Mo2CTx MXene and Ni,Co-MOF yields an outstanding performance. In a three-electrode system with 1 M KOH, the Mo2CTx/Ni,Co-MOF composite shows a specific capacitance of 58 mAh g-1 (56.26 mAh cm-3) at 1 A g-1. When used in a Mo2CTx/Ni,Co-MOF//AC asymmetric supercapacitor, it achieves an energy density of 22.7 Wh kg-1(0.022 Wh cm-3) at a power density of 293 W kg-1 (0.284 W cm-3). Future work will focus on enhancing synthesis methods, exploring different bimetallic combinations, and optimizing electrode designs for gas sensors, batteries, fuel cells, biological sensors, and so on, with outstanding performance and sustainability.

Hydrothermal preparation of cotton-based rGO/N-doped porous carbon as electrode materials of supercapacitors

Porous carbon electrode materials are commonly used in supercapacitors due to their inexpensive raw materials, simple processing, and low pollution, aligning with the vision for green energy storage. Consequently, there is a current trend to discover porous carbon electrode materials with superior electrochemical properties. To enhance the pore volume ratio and electrochemical performance of porous carbon materials, this study proposes a hydrothermal method to pretreat the raw materials, facilitating the doping of nitrogen from urea. Moreover, graphene is introduced for its excellent conductivity, which can further improve the electrochemical properties of the material. We found a new one-step reduction Graphene Oxide (rGO)and the doping of nitrogen (N) elements were optimized by hydrothermal method, the wettability and pseudo-capacitance performance of the material are improved, and HTPC-700 shows a very excellent specific capacitance, its specific capacitance reaches 600 F g−1 at a current density of 0.5 A g−1, and it even reaches 260 F g−1 at a current density of 1 A g−1. Meanwhile the power density and energy density are respectively 74 W h kg−1 and 280 W kg−1. It also exhibits a remarkable capacitance retention rate of over 98.7 % after 5000 cycles at a current density of 1 A g−1. Additionally, it demonstrates a rich ant nest-like pore structure and good specific surface area of 2427 m2/g, and a large pore volume of 1.09 cm3/g after carbonization and KOH activation. This study offers a novel doping method and provides a unique perspective for the development of porous carbon electrodes.

Renewable synthesis of MoO3 nanosheets via low temperature phase transition for supercapacitor application

2D transition metal oxides have created revolution in the field of supercapacitors due to their fabulous electrochemical performance and stability. Molybdenum trioxides (MoO3) are one of the most prominent solid-state materials employed in energy storage applications. In this present work, we report a non-laborious physical vapor deposition (PVD) and ultrasonic extraction (USE) followed by vacuum assisted solvothermal treatment (VST) route (DEST), to produce 2D MoO3 nanosheets, without any complex equipment requirements. Phase transition in MoO3 is often achieved at very high temperatures by other reported works. But our well-thought-out, robust approach led to a phase transition from one phase to another phase, for e.g., hexagonal (h-MoO3) to orthorhombic (α-MoO3) structure at very low temperature (90 °C), using a green solvent (H2O) and renewable energy. This was achieved by implementing the concept of oxygen vacancy defects and solvolysis. The synthesized 2D nanomaterials were investigated for electrochemical performance as supercapacitor electrode materials. The α-MoO3 electrode material has shown supreme capacitance (256 Fg−1) than its counterpart h-MoO3 and mixed phases (h and α) of MoO3 (< 50 Fg−1). Thus, this work opens up a new possibility to synthesize electrocapacitive 2D MoO3 nanosheets in an eco-friendly and energy efficient way; hence can contribute in renewable circular economy.