Binder-free Electrode Materials Research Articles

Facile synthesis of cotton flower like Ni–Co/Ni–Co–O–P as bifunctional active material for alkaline overall water splitting and acetaminophen sensing

The development of electrode materials with simple preparation, favorable price, excellent electrocatalytic activity, and stability are some of the most important issues in the field of electrochemistry. Herein, we prepared Ni–Co/Ni–Co–O–P cotton flower like on a copper sheet (CS) by a convenient, efficient, and scalable electrodeposition method. The Ni–Co/Ni–Co–O–P was employed as effective binder free electrode material in two different applications such as electrocatalytic water splitting and acetaminophen (APAP) sensor. Remarkably, the Ni–Co/Ni–Co–O–P@CS exhibits low overpotentials of 310 and 90 mV at 10 mA cm−2 for oxygen and hydrogen evolution reactions in alkaline media, respectively. Besides, the Ni–Co/Ni–Co–O–P@CS || Ni–Co/Ni–Co–O–P@CS couple needs a low cell voltage of 1.62 V to achieve a current density of 10 mA cm−2, and its potential change is negligible after 20 h of continuous operation. Furthermore, Ni–Co/Ni–Co–O–P displays good electrochemical sensing performance toward APAP with a high sensitivity of 803.74 μA mM−1cm−2, low limit of detection of 0.16 μM, a wide linear range of 0.05 mM–3 mM, and a fast response time of 3.3 s. This work proposes a simple approach for synthesis of Ni–Co/Ni–Co–O–P as an efficient electrode material for water splitting and APAP sensing.

A high-performance asymmetric supercapacitor consists of binder free electrode materials of bimetallic hydrogen phosphate (MnCo(HPO4)) hexagonal tubes and graphene ink

Novel bimetallic manganese-cobalt hydrogen phosphate (MnxCox(HPO4)) hexagonal tubes were efficiently prepared by a direct and simple chemical bath deposition (CBD) procedure. The prepared MnxCox(HPO4) materials have been analysed through Fourier transform infrared (FT-IR), thermogravimetric analysis (TGA), and X-ray diffraction (XRD) methods. The surface morphology and the particle size of the materials were studied using field emission scanning electron microscopy (FE-SEM) and high-resolution transmission electron microscopy (HR-TEM). The textural characteristics and elemental composition of the MnxCox(HPO4) were measured using nitrogen sorption isotherms and X-ray photoelectron spectroscopy (XPS) analysis. Owing to its unique hexagonal structures and porous nature, the Mn0.5Co0.5(HPO4) electrode is measured via a three-electrode system and achieved the highest specific capacitance of 1,727 F g−1 at the current density of 1.0 A g−1. An aqueous asymmetric supercapacitor (AAS), Mn0.5Co0.5(HPO4)//G-ink device based on Mn0.5Co0.5(HPO4) as the cathode and graphene ink (G-ink) as an anode material. The fabricated device might function well in a large operating potential window of +1.6 V. The Mn0.5Co0.5(HPO4)//G-ink AAS exhibited the maximum power and specific energy of 9,000 W kg−1 and 56.16 Wh kg−1, correspondingly at 1.0 A g−1. Furthermore, the fabricated device could withstand 95.5% of its primary capacitance after 5,000 galvanostatic charge/discharge (GCD) turns, which illustrates that the materials could be a prominent contender for supercapacitor applications.

Lokta paper-derived free-standing carbon as a binder-free electrode material for high-performance supercapacitors

In this paper, we introduced an eco-friendly process to dramatically simplify carbon microfiber fabrication from discarded lokta paper (LP) from Nepal. Herein, carbonization followed by the activation processes was applied to transform the lokta paper into flexible, free-standing, and porous carbon fiber paper. The as-prepared activated carbonized lokta paper (ACLP) was characterized with state-of-the-art techniques. The electrochemical tests were performed in alkaline (6 M KOH), acidic (1 M H2SO4), and neutral (1 M Na2SO4) aqueous electrolytes. In all cases, the ACLP showed enhanced performance compared to the carbonized lokta paper without activation (CLP). The ACLP exhibited areal capacitance of 380, 428, and 273 mF/cm2 at the current density of 1 mA/cm2 in 6 M KOH, 1 M H2SO4, and 1 M Na2SO4 electrolytes, respectively with excellent capacity retention (above 100%) after 5000 cycles. Further, we assembled a supercapacitor device with key components (electrodes and separator) coming from lokta paper. The pristine lokta paper was used as a separator, whereas the ACLP was used as positive and negative electrodes in the supercapacitor. The device exhibited promising areal capacitance of 272, 405, and 124 mF/cm2 in alkaline, acid, and neutral electrolytes, respectively at the current density of 1 mA/cm2, with excellent durability after 5000 cycles. An energy density of 56.25 mWh/cm2 at a power density of 997 mW/cm2 under 1 M H2SO4 electrolyte was recorded. Overall, this study demonstrated an environmentally friendly approach to valorize a discarded paper into high-performance supercapacitor electrode material.

Glycol-assisted Cu-doped ZnS polyhedron-like structure as binder-free novel electrode materials

The facile, efficient, and straightforward preparation of electrode material for energy storage devices has drawn considerable interest for practical applications. In this study, we have synthesized the polyhedron Cu-doped ZnS (ZnS:Cu) structure on carbon cloth (CC) using a single-step glycol-assisted process. The highly interconnected polyhedron shaped ZnS:Cu functions as positive electrode material in an aqueous electrolyte for supercapacitor application. The ZnS:Cu polyhedron-like structures with higher electroactive sites and synergistic effect exhibited higher specific capacitance of 468 F g−1 at 1 Ag−1 and cycling stability of 890.5% after 5,000 cycles. The better electrochemical performance and higher cycling stability of ZnS:Cu can be dedicated to interconnected polyhedron-like structures, doping of Cu in ZnS, and binder-free electrode design. This underlines the potential of the Cu-doped ZnS-based supercapacitor for next-generation energy storage devices.

Manganese-doped zinc sulfide binary nanostructures as binder-free electrode materials for supercapattery

Manganese-doped zinc sulfide binary nanostructures as binder-free electrode materials for supercapattery

Averrhoa bilimbi leaves-derived oxygen doped 3D-linked hierarchical porous carbon as high-quality electrode material for symmetric supercapacitor

This successfully performed a facile one-way KOH impregnation strategy, to hierarchically prepare interconnected porous carbon and self-oxygen doped from Averrhoa bilimbi leaves waste, as binder-free electrode material (PCBLs) for high-quality symmetrical supercapacitor. 3D porous structure and surface area PCBLs-derived controlled by different KOH concentrated solution. KOH infiltrated into precursor as act activation agent to completely removed inorganic impurities, result high carbon content of 85.54–87.22% with oxygen functional group of 10.61–14.71%. The precursor impregnated at 0.5 mol/L possessed excellent micropores 87.69%, adjusting mesopores and appropriate amounts of oxygen doped of 14.71%. As a result, it performed high performance of symmetrical supercapacitor. Furthermore, the electrochemical performance was evaluated within a two-electrode system using a binder-free solid coin design in different aqueous electrolytes of 1 M H2SO4, NaOH, and Na2SO4, respectively. This indicated that the symmetric supercapacitor-based PCBL-5 had a high specific capacitance of 293 F g−1 in 1 M H2SO4 aqueous electrolyte at a current density of 1.0 A g−1. It also showed impressive energy densities of 26.54, 21.85, and 16.12 Wh kg−1 in 1 M H2SO4, NaOH, and Na2SO4, at an optimum power density of 178.44 W kg−1. The observed desirable excellent material and electrochemical behaviors of the new source hierarchical porous carbon derived from Averrhoa bilimbi leaves waste would be a competitive candidate as electrode material in the development of high-quality supercapacitor devices.

Novel electrodeposition of bud-like cobalt/zinc metal-organic-framework onto nickel foam as a high-performance binder-free electrode material for supercapacitor applications

In this paper, bimetal-terephthalate (i.e. CoZn-bdc) metal-organic-framework (MOF) structures with bud-like morphology are grown onto nickel foam by a one-step reductive electrochemical procedure, which are used as electrode active materials for supercapacitor. The synthesized CoZn-bdc material is characterized by powder X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy and energy dispersive X-ray spectroscopy analyzes. The acquired results verified the formation of the bud-like MOF structures with mixed metallic centers (i.e. 3.89% Co and 3.07 % Zn) onto Ni-foam substrate. Electrochemical performances of the CoZn-bdc/Ni foam were also investigated by galvanostatic charge-discharge (GCD) tests, which exhibited high specific capacitance of 1205 F g–1 and 94.8 % capacity retention after 8000 cycling at 2 A g–1. Finally, the as-prepared samples are found to be of great potential as a high-performance electrode active material for electrochemical supercapacitors.

Constructing a novel carbon skeleton to anchor Sn/SnO2 nanodots for flexible supercapacitor with excellent rate capability

Designing SnO2/carbon composites is an effective strategy to improve the conductivity and buffer the volume expansion of SnO2. However, it remains a challenge to combine SnO2 and carbon materials tightly as a stable integration. Herein, a facile and versatile strategy of Sn/SnO2 nanodots anchored tightly into carbon nanofibers (CNFs) with the decoration of graphene quantum dots (GQDs) for high performance supercapacitor is reported. Through a simple electrospinning and carbonization reduction process, a novel multidimensional carbon skeleton of GQD/CNF effectively improves the conductivity, and importantly, abundant Sn–O–C covalent bonds are constructed to anchor SnO2 nanodots tightly into GQD/CNF, suppressing SnO2 aggregation and facilitating electron/ion transfer kinetics. Consequently, as self-supporting and binder-free electrode material, Sn/SnO2/GQD/CNF displays high specific capacitance of 168.6 mA h g−1 (1349 F g−1) at 1 A g−1 with excellent rate capability (88.9% retention at 20 A g−1). Furthermore, a flexible solid-state asymmetric supercapacitor based on Sn/SnO2/GQD/CNF and GQD/CNF achieves a high energy density of 32.3 W h kg−1 at a power density of 800 W kg−1 with remarkable flexibility and cycling stability (86.1% retention after 5000 cycles). The excellent electrochemical performances demonstrate that this novel carbon skeleton anchored active materials shows great potential for electrochemical energy storage applications.

Unique core-shell Co2(OH)2CO3@MOF nanoarrays with remarkably improved cycling life for high performance pseudocapacitors

Binder-free composite electrode material consisted of cobalt hydroxycarbonates (Co2(OH)2CO3) and bimetallic metal-organic-framework (NiCo-MOF) is facilely prepared for the first time through a hydrothermal-solvothermal combined method. The composite Co2(OH)2CO3@MOF presents a unique core-shell architecture, which endows remarkable superiority such as great surface area, short diffusion pathway and component synergy effects, leading to splendid supercapacitor performance. The optimal composite electrode exhibits ultrahigh specific capacitance (3232 F g−1 at 1 A g−1), good rate capability and outstanding cycle life (84.1% after 5000 cycles). In addition, an asymmetric supercapacitor (ASC) device Co2(OH)2CO3@MOF-2//AC (active carbon) delivers a high energy density (55.2 W h kg−1 @ 0.8 kW kg−1) and excellent cycle life (89.2% after 6000 cycles). These values are comparable to or even better than the recently reported related electrode materials in literatures (Table S1), demonstrating the prospect for future high performance energy storage devices. The smart strategy reported here can also be promoted to other metal hydroxycarbonates with advanced hierarchical core-shell structures for high performance electrochemical devices.

Electrodeposited MnS@Ni(OH)2 core-shell hybrids as an efficient electrode materials for symmetric supercapacitor applications

The usage of composites with chalcogenides and hydroxides are fascinated prodigious consideration for supercapacitor application. In this work, the layer by layer assembly of MnS@Ni(OH)2 core-shell hybrids were prepared by facile electrodeposition method and utilized as a binder-free electrode material for symmetric supercapacitor application. Systematic analyses have been done to confirms the formation and morphological features of MnS@Ni(OH)2 core-shell hybrids. The core-shell hybrids of MnS@Ni(OH)2 exhibits the redox behavior and delivered a high specific capacity of 2612 F g­1 at a current density of 1 A g­1 with excellent cycle stability of 88% capacity retention over 5000th cycle in 3 M KOH electrolyte. The delivered specific capacity is the highest among MnS and Ni(OH) based supercapacitors and also higher than various types of other metal oxide-based supercapacitors. Moreover, a sandwich-like solid-state symmetric supercapacitor was fabricated using MnS@Ni(OH)2 core-shell hybrid, and thus provided the specific capacity of 168.75 F g­1 at a current density of 1 A g­1 with the energy and power density of 60 Wh kg−1 and 800 W kg−1, respectively. The attained results recommended that the MnS@Ni(OH)2 core-shell hybrid has the probability to be applied as a novel, robust, and low-cost electrode material for supercapacitor energy storage devices.

Metal-organic framework-derived walnut-like hierarchical Co-O-nanosheets as an advanced binder-free electrode material for flexible supercapacitor

Cobalt-based nanostructured are favorite pseudocapacitive electrode materials for supercapacitors (SCs) due to the low cost and high theoretical capacitance. However, their unsatisfied electrochemical stability severely limits them for practical applications. In this work, metal-organic framework (MOF) derived cobalt oxide (Co-O) hierarchical walnut-like nanosheets supported on carbon fiber cloth (CFC) (denoted as Co-O-NSs@CFC) as a binder-free electrode material was synthesized via scalable and facile hydrothermal method. Results exhibited that the Co-O-NSs@CFC showed crystalline and porous features with high surface area and can be utilized as cathode material for high-performance supercapacitors. The Co-O-NSs@CFC demonstrated excellent charge storage performance with balanced capacitive/diffusion-type charge storage (54% capacitive at 1 mV/s) and achieved 842 F/g (421 C/g) at 1 A/g with outstanding cycling stability of 96.4% till 10,000 cycles. Furthermore, a flexible asymmetric SC was assembled using activated carbon as anode and Co-O-NSs@CFC as a cathode with PVA/KOH as electrolyte (denoted as f-Co-O-NSs@CFC||AC). The f-Co-O-NSs@CFC||AC delivers a high specific capacitance of 178 F/g at 1.5 A/g, excellent energy density of 55.7 Wh/kg at a power density of 1125.9 W/kg with outstanding capacitance retention of 94.5% after 5000 cycles with stable flexible performance. This work shows a remarkable electrochemical performance that could offer high-energy-density electrode materials for flexible SCs.

Carbon dots decorated zinc cobaltite nanowires-assembled hierarchical arrays supported on nickel foam as binder-free electrodes for high performance supercapacitors

Hierarchical and binder-free electrode materials with large electroactive sites and low contact resistance are benefit for electrochemical capacitors. Herein, this paper reports the binder-free and hierarchical ZnCo 2 O 4 arrays decorated with carbon dots (CDs/ZnCo 2 O 4 ) on nickel foam by hydrothermal route. The CDs/ZnCo 2 O 4 arrays exhibit the nanowires-assembled hierarchical grass-like structure. The outward directed nanowires yield high surface-to-volume ratio. The nanowires exhibit the average length of 1 μm and diameter of 50 nm. The specific capacitance of the CDs/ZnCo 2 O 4 can reach 1937 F/g higher than the 1192 F/g of bare ZnCo 2 O 4 at 1 A/g. And 78.5% capacitance retention rate is achieved while the current density increases from 0.5 to 8 A/g. 90% of the capacitance retention over 5000 charge-discharge cycles at 15 A/g indicates high cycling stability. These boosted electrochemical performances are attributed to the structural feature with exposed electroactive sites, high electrical conductivity assisted by CDs, and opened interspaces for electrolyte ion diffusion. Asymmetric two-electrode system assembled with CDs/ZnCo 2 O 4 and activated carbon delivers a high-energy density of 54.94 W h/kg at 425.3 W/kg and retains an energy density of 13.23 W h/kg at 6804 W/kg. This study provides a new approach to design high-performance electrode materials for supercapacitors. • Hierarchical ZnCo 2 O 4 arrays were decorated with carbon dots (CDs). • CDs/ZnCo 2 O 4 electrode exhibited 1937 F/g at 1 A/g higher than bare ZnCo 2 O 4 . • Assembled two-electrode system delivered 54.94 W h/kg at 425.3 W/kg.

A High-Performance Asymmetric Supercapacitor Consists of Binder Free Electrode Materials of Bimetallic Hydrogen Phosphate (Mnco(Hpo4)) Hexagonal Tubes and Graphene Ink

A High-Performance Asymmetric Supercapacitor Consists of Binder Free Electrode Materials of Bimetallic Hydrogen Phosphate (Mnco(Hpo4)) Hexagonal Tubes and Graphene Ink

Facile synthesis of MnCo2S4 nanosheets as a binder-free electrode material for high performance supercapacitor applications

MnCo2S4 porous nanosheets with excellent electrochemical performance were synthesized by using a simple and effective approach at relatively low temperatures.

Hydrothermal synthesis of Cu-doped CoS2@NF as high performance binder free electrode material for supercapacitors applications

In current work, we are reporting the synthesis of pure and Cu doped CoS2 nanoparticles on Nickel foam by one step hydrothermal method. The physiochemical properties of Cu.CoS2 in comparison to pure CoS2 were studied with the help of XRD, FT-IR, SEM, EDX and I–V measurements. Cubic phase structure of CoS2 and Cu.CoS2 was confirmed by XRD data. Characteristics FT-IR vibrational bands revealed the presence of Co–S bonds. SEM micrographs showed cottony spherical particles of CoS2 and Cu.CoS2 with some degree of aggregation. Ohmic contacts were formed in CoS2 after doping with Cu ions, which enhanced the conductivity of Cu.CoS2 to 3.39 × 10−3 Sm−1, as compared to 8.26 × 10−6 Sm−1 for pure CoS2. When investigated for electrochemical performance, as fabricated binder free Cu.CoS2 showed outstanding supercapacitive performance with specific capacitance of 503 Fg-1 at 1 Ag-1. Additionally, Cu.CoS2 exhibited great cyclic stability with 91.1% capacity retention at 9 Ag-1 after 3000 cycles. Remarkable specific capacitance, rate capability and cyclic stability of Cu doped CoS2 can be accredited to its unique self-supporting design, morphological contributions, high conductivity and reduced grain size. Consequently, Cu.CoS2@NF electrode can act as promising candidate for energy storage applications.

Design of open-porous three-dimensional starfish-like Co3O4/Ni forest electrode for efficient energy storage devices

A binder-free positive electrode material of 3D starfish-like Co3O4/Ni forest is fabricated via a novel and facile hydrothermal process followed by thermal treatment. The morphological studies clearly showed the construction of starfish-like micro-flowers of Co3O4 nanostructure forest densely covered on the entire Ni current collector. The 3D-Co3O4/Ni electrode displayed an areal capacity as high as 143.28 mC cm−2 at 0.5 mA cm−2 and higher stability of 88.4% after 5000 cycles. Moreover, the fabricated 3D-Co3O4/Ni||3D-Bi2O3/Ti supercapattery delivered a maximum areal capacitance of 24.73 mF cm−2, the energy density of 6.73 μWh cm−2 and power density of 5250 μW cm−2 with good cycling stability> 71% capacity retention after 5000 cycles. The higher electrochemical performance of the electrode is delivered due to the availability of abundant electrochemically active sites in the 3D starfish-like Co3O4 microflower, which facilitates a higher electrochemical reaction. The starfish-like forest architectures allow rapid ion diffusion, and the binder-free electrode reduces the contact resistance, which fasten the electron transport. These tolerable results prompt the as-prepared electrode with 3D starfish-like Co3O4 microflower morphology as an auspicious positive electrode material for electrochemical energy storage devices.

Manganese-doped tungsten disulfide microcones as binder-free electrode for high performance asymmetric supercapacitor

Manganese-doped tungstate sulfide (Mn-WS2) microcones were developed with varying levels of Mn, grown directly on electrically conductive Ni foam, and used as binder-free electrode material for supercapacitors. The experimental research indicates that Mn-WS2 microcones has significantly improved electrochemical activity and cyclic stability compared with pure WS2 due to additional ion diffusion channels. A strong synergy between the transitional metal ions in Mn-WS2 remarkably improved the redox activity, rate capability, and cycling stability. The Mn-WS2 microcones had a high specific capacitance of 107.79 mA h g−1 at 1 A g−1, a high rate capability of 75.18% at 20 A g−1, and 96.1% capacitance retention after 10,000 charge–discharge cycles. The effect of Mn ions on the electrochemical performance of WS2 microcones was also studied in detail. The enhanced electrochemical performance of the electrode can be attributed to the unique structural features of WS2 microcones arrays grown in Ni foam, which allow the surface of WS2 to be highly accessible to electrolyte ions. Furthermore, an all solid state asymmetric supercapacitor (ASCs) assembled with Mn-WS2 microcones as anode and GO/Fe3O4 cathode (Mn-WS2//PVA-KOH// GO/Fe3O4) delivered high specific energy of 70.65 W h kg−1 at 997.41 W kg−1. These results confirm that Mn-WS2 with outstanding electrochemical properties could be a promising electrode material for practical application in electrochemical energy storage field.

Highly hydrophilic electrodeposited NiS/Ni3S2 interlaced nanosheets with surface-enriched Ni3+ sites as binder-free flexible cathodes for high-rate hybrid supercapacitors

In this study, nanostructured nickel sulfides (NiS, Ni3S2 and NiS/Ni3S2) were fabricated directly on the surface of flexible carbon fiber cloths by simply modifying the deposition parameters of pulse-reversal (PR) electrodeposition method and utilized as binder-free flexible electrodes for aqueous hybrid supercapacitors (SCs). X-ray photoelectron spectroscopy and contact angle measurement studies verifies that the surface of heterostructure NiS/Ni3S2 electrode has enriched Ni3+ sites and highly hydrophilic nature. Consequently, the heterostructure NiS/Ni3S2 electrode demonstrated superior rate capability than that of both single phase NiS and Ni3S2 electrodes. Additionally, the hybrid SC device based on the flexible NiS/Ni3S2 electrode delivered a capacity of 40.4 mAh g−1 at a current density of 2 A g−1 and representing a maximum energy density of 32.3 Wh kg−1 at an impressive power density of 1.6 kW kg−1. Furthermore, the device provided excellent electrochemical stability with a capacity retention of 86.2%, even after a 120-h floating test. Hence, the heterostructure NiS/Ni3S2 with interlaced nanosheets morphology should be considered as promising binder-free flexible electrode materials for next-generation energy storage applications.

Monolithic Carbon Spherogels as Freestanding Electrodes for Supercapacitors

This study presents a direct application for freestanding and monolithic carbon spherogels, which are highly porous carbon aerogels solely composed of hollow nanospheres, as binder-free electrode materials for supercapacitors. By applying polystyrene nanospheres as templating agents in the size range of 277–907 nm and concentrations from 1.5 to 12 wt % in the sol–gel polymerization process of resorcinol–formaldehyde, we can distinctly tailor the hollow spheres’ pore arrangement and thickness of the microporous carbon walls. Furthermore, the required synthesis conditions for mechanically processable (sliceable) carbon spherogels are explored. Following physical activation with carbon dioxide, only 277 nm templated samples, featuring one thin-walled (<20 nm) and one thick-walled (>60 nm) variant, retain a freestanding bulk constitution and hence are suitable for the application as binder-free electrodes. The electrochemical evaluation demonstrates the advantage of hollow carbon sphere aerogels in comparison to conventional carbon aerogels with respect to capacitance, particularly at high scan rates. The analysis of the electrolyte diffusion kinetics and the network morphology after 10,000 charge/discharge cycles reveals the necessity of wall thickness optimization. Thick-walled variants are favored due to a much higher rate capability of 30 kW kg–1 compared to 10 kW kg–1). Additionally, a post-mortem TEM analysis reveals the loss of a central cavity and sphere degradation in thin-walled samples.

A new hierarchically porous Cu-MOF composited with rGO as an efficient hybrid supercapacitor electrode material

Exploring new materials for efficient energy storage is imperative to derive uninterrupted energy supply from non-conventional sustainable sources. The present paper reports on the synthesis of a new Cu-MOF (HMRL-1), involving the reaction of a tetracarboxylic linker and Cu2+ salt under solvothermal conditions. Using a simple ultrasonication approach, the as-synthesized MOF has been further used to fabricate a composite with reduced graphene oxide (rGO) (R). The resulting composite (HMRL-1/R) has been explored as a binder-free supercapacitor electrode material for deriving enhanced charge storage capacity. The supercapacitor performance of the composite material has been investigated by cyclic voltammetry (CV), galvanostatic charge-discharge (GCD), and electrochemical impedance spectroscopy (EIS). The electrochemical investigations reveal that HMRL-1/R composite exhibits hybrid capacitive features with a specific capacitance (CS) of 366.6 Fg−1 at 1 Ag−1 and excellent cyclic stability and performance retention, which is much higher than that of pristine HMRL-1 and R due to their synergistic effect. All the findings suggest that as-prepared material is a promising candidate for an electrode material in supercapacitor applications.