Research Progress of NiMn Layered Double Hydroxides for Supercapacitors: A Review

Recent Progress in MXene-Based Materials for Supercapacitors and Electrochemical Sensing Applications

In recent years, MXene-based materials have received extensive interest for a variety of applications, including energy storage, solar cells, sensors, photo-catalysis, etc., due to their extraordinary optoelectronic and physicochemical properties. MXene-based electrode materials exhibit excellent electrochemical properties for supercapacitors (SCs) and electrochemical sensing technologies due to the presence of acceptable electrocatalytic characteristics. Herein, we reviewed publications from recent years on the development of MXenes and their composites for SCs and electrochemical sensors. MXene-based materials with polymers, metal oxides, metal sulfides or selenides; metal-organic frameworks (MOFs); layered double hydroxides (LDHs); and carbon-based materials such as graphene, carbon nanotubes, etc., have been reviewed for their potential applications in SCs. MXene-based hybrid composites have also been reviewed for electrochemical sensing applications. Furthermore, challenges and future perspectives are discussed. It is expected that the present article will be beneficial for scientists working on the modification of MXene-based materials for SCs and electrochemical sensing technologies.

Advances in anion-intercalated layered double hydroxides for supercapacitors: study of chemical modifications and classifications

Hybrid material-based electrochemical supercapacitors (SCs) possessing improved energy density (ED), enhanced stability, high porosity, and a large accessible surface area have attracted attention as promising energy storage devices. SCs also demonstrate excellent specific capacitance (Cs) across various current densities, increased capacitance, and high cell voltages, all contributing to improved ED. Layered double hydroxides (LDHs), with their anionic exchange capabilities and laminar structures, offer significant potential for boosting charge transfer in SCs. This review provides a comprehensive overview of the recent advances in anion-based LDHs, discussing their storage mechanisms, chemical modifications, and classification based on interlayer anions. The roles of different anions, including monovalent, divalent, and polyoxometalates, in enhancing storage properties are examined. In addition, the challenges, future research directions, and practical perspectives of anion-storing LDHs are presented. Hence, this review provides a concise overview of anion-based LDHs for SCs, highlighting their potential significance in energy storage applications.

Hierarchical core-shelled CoMo layered double hydroxide@CuCo2S4 nanowire arrays/nickel foam for advanced hybrid supercapacitors

The development of core-shelled heterostructures with the unique morphology can improve the electrochemical properties of hybrid supercapacitors (HSC). Here, CuCo2S4 nanowire arrays (NWAs) are vertically grown on nickel foam (NF) utilizing hydrothermal synthesis. Then, CoMo-LDH nanosheets are uniformly deposited on the CuCo2S4 NWAs by electrodeposition to obtain the CoMo-LDH@CuCo2S4 NWAs/NF electrode. Due to the superior conductivity of CuCo2S4 (core) and good redox activity of CoMo-LDH (shell), the electrode shows excellent electrochemical properties. The electrode's specific capacity is 1271.4 C g-1 at 1 A g-1, and after 10, 000 cycles, its capacity retention ratio is 92.2 % at 10 A g-1. At a power density of 983.9 W kg-1, the CoMo-LDH@CuCo2S4 NWAs/NF//AC/NF device has an energy density of 52.2 Wh kg-1. This indicates that CoMo-LDH@CuCo2S4/NF has a great potential for supercapacitors.

Synergistic Effects of ZnO@NiM'-Layered Double Hydroxide (M' = Mn, Co, and Fe) Composites on Supercapacitor Performance: A Comparative Evaluation

The development of supercapacitors is pivotal for sustainable energy storage solutions, necessitating the advancement of innovative electrode materials to supplant fossil-fuel-based energy sources. Zinc oxide (ZnO) is widely studied for use in supercapacitor electrodes because of its beneficial physicochemical properties, including excellent chemical and thermal stability, semiconducting characteristics, low cost, and environmentally friendly nature. In this study, ZnO nanorods were synthesized using a simple hydrothermal method and then combined with various Ni-based layered double hydroxides (LDHs) [NiM'-LDHs (M' = Mn, Co, and Fe)] to improve the electrochemical performance of the ZnO nanorods. These LDHs are well-known for their outstanding electrochemical and electronic properties, high specific capacitance, and efficient dispersion of cations within host nanolayers. The synthesized composites ZnO@NiMn-LDH, ZnO@NiCo-LDH, and ZnO@NiFe-LDH exhibit enhanced specific capacitances of 569.3, 284.6, and 133.0 F/g, respectively, at a current rate of 1 A/g, outperforming bare ZnO (98.4 F/g). Notably, ZnO@NiMn-LDH demonstrates superior electrochemical performance along with a capacitance retention of 76%, compared to ZnO@NiCo-LDH (58%), ZnO@NiFe-LDH (49%), and bare ZnO (23%) over 5000 cycles. Furthermore, an asymmetric supercapacitor (ASC) was developed by using ZnO@NiMn-LDH as the positive electrode and activated carbon (AC) as the negative electrode to assess its practical applicability. The fabricated ASC (ZnO@NiMn-LDH//AC) demonstrated a specific capacitance of 45.22 F/g at a current rate of 1 A/g, an energy density of 16.08 W h/kg at a power density of 798.8 W/kg, and a capacitance retention of 75% over 5000 cycles. These findings underscore the potential of the composite formation of ZnO with Ni-based LDHs in advancing the efficiency and durability of supercapacitors.

Surface-Activated Ti3C2Tx Adsorption of Acetylene Black Coupled with Polyaniline as a Signal Tag for the Detection of the ESAT-6 Antigen of Mycobacterium tuberculosis

Early secretory antigenic target-6 (ESAT-6) is regarded as the most immunogenic protein produced by Mycobacterium tuberculosis, whose detection is of great clinical significance for tuberculosis diagnosis. However, the detection of the ESAT-6 antigen has been hampered by the expensive cost and complex experimental procedures, resulting in low sensitivity. Herein, we developed a titanium carbide (Ti3C2Tx)-based aptasensor for ESAT-6 detection utilizing a triple-signal amplification strategy. First, acetylene black (AB) was immobilized on Ti3C2Tx through a cross-linking reaction to form the Ti3C2Tx-AB-PAn nanocomposite. Meanwhile, AB served as a conductive bridge, and Ti3C2Tx can synergistically promote the electron transfer of PAn. Ti3C2Tx-AB-PAn exhibited outstanding conductivity, high electrochemical signals, and abundant sites for the loading of ESAT-6 binding aptamer II (EBA II) to form a novel signal tag. Second, N-CNTs were adsorbed on NiMn layered double hydride (NiMn LDH) nanoflowers to obtain NiMn LDH/N-CNTs, exhibiting excellent conductivity and preeminent stability to be used as electrode modification materials. Third, the biotinylated EBA (EBA I) was immobilized onto a streptavidin-coated sensing interface, forming an amplification platform for further signal enhancement. More importantly, as a result of the synergistic effect of the triple-signal amplification platform, the aptasensor exhibited a wide detection linear range from 10 fg mL-1 to 100 ng mL-1 and a detection limit of 4.07 fg mL-1 for ESAT-6. We envision that our aptasensor provides a way for the detection of ESAT-6 to assist in the diagnosis of tuberculosis.

Surface modification of two-dimensional layered double hydroxide nanoparticles with biopolymers for biomedical applications

Layered double hydroxides (LDHs) are appealing nanomaterials for (bio)medical applications and their potential is threefold. One can gain advantage of the structure of LDH frame (i.e., layered morphology), anion exchanging property towards drugs with acidic character and tendency for facile surface modification with biopolymers. This review focuses on the third aspect, as it is necessary to evaluate the advantages of polymer adsorption on LDH surfaces. Beside the short discussion on fundamental and structural features of LDHs, LDH-biopolymer interactions will be classified in terms of the effect on the colloidal stability of the dispersions. Thereafter, an overview on the biocompatibility and biomedical applications of LDH-biopolymer composite materials will be given. Finally, the advances made in the field will be summarized and future research directions will be suggested.

Formation of a CoMn-Layered Double Hydroxide/Graphite Supercapacitor by a Single Electrochemical Step

Hybrid electric storage systems that combine capacitive and faradaic materials need to be well designed to benefit from the advantages of batteries and supercapacitors. The ultimate capacitive material is graphite (GR), yet high capacitance is usually not achieved due to restacking of its sheets. Therefore, an appealing approach to achieve high power and energy systems is to embed a faradaic 2D material in between the graphite sheets. Here, a simple one-step approach was developed, whereby a faradaic material [layered double hydroxide (LDH)] was electrochemically formed inside electrochemically exfoliated graphite. Specifically, GR was exfoliated under negative potentials by CoII and, in the presence of MnII , formed GR-CoMn-LDH, which exhibited a high areal capacitance and energy density. The high areal capacitance was attributed to the exfoliation of the graphite at very negative potentials to form a 3D foam-like structure driven by hydrogen evolution as well as the deposition of CoMn-LDH due to hydroxide ion generation inside the GR sheets. The ratio between the CoII and MnII in the CoMn-LDH was optimized and analyzed, and the electrochemical performance was studied. Analysis of a cross-section of the GR-CoMn-LDH confirmed the deposition of LDH inside the GR layers. The areal capacitance of the electrode was 186 mF cm-2 at a scan rate of 2 mV s-1 . Finally, an asymmetric supercapacitor was assembled with GR-CoMn-LDH and exfoliated graphite as the positive and negative electrodes, respectively, yielding an energy density of 96.1 μWh cm-3 and a power density of 5 mW cm-3 .

High-performance flexible supercapacitor enabled by Polypyrrole-coated NiCoP@CNT electrode for wearable devices

As a pseudocapacitive electrode material, nickel-cobalt bimetallic phosphide has attracted wide attention with its advantage in capacitance and chemical activity. While, like Ni-Co oxides or sulfides, the application of nickel-cobalt bimetallic phosphide is generally hampered by its confined conductivity, low chemical stability and unsatisfactory cycle durability. Herein, this work demonstrates a NiCoP@CNT@PPy (NCP@CNT@PPy) composite that is obtained by polymerizing pyrrole monomer on the surface of NiCoP@CNT complex. According to density functional theory (DFT), it is theoretically demonstrated that the bimetallic Ni-Co phosphide (NiCoP) can exhibit more electrons near the Fermi level than single Ni or Co phosphide. Under the combined effects of carboxylic carbon nanotubes (c-CNTs) and polypyrrole (PPy), the NCP@CNT@PPy electrode exhibits excellent electrochemical performance. In addition, a flexible asymmetric supercapacitor (ASC) is prepared, which demonstrated high energy density and admirable heat-resistance and flexibility performance, showing huge potential in the application of heat-resistant storage energy systems and portable wearable devices.

A doping element improving the properties of catalysis: in situ Raman spectroscopy insights into Mn-doped NiMn layered double hydroxide for the urea oxidation reaction

Potential dependent in situ Raman spectra confirm that Mn doping enables a negative shift in Ni(ii) oxidation onset potential.

Layered double hydroxide-modified membranes for water treatment: Recent advances and prospects

Layered double hydroxides (LDHs) represent an exciting class of two-dimensional inorganic materials with unique physicochemical properties. They have been widely employed in water treatment due to their high surface areas, excellent ion exchange capacities, and highly tunable structures. They have also been employed in the fabrication and development of membranes for water treatment. 2D nanostructures as well as tailorable "structure forming units", surface functionalization with desired moieties, and interlayer galleries with adjustable heights and internal compositions make them attractive materials for membrane separations. This paper critically overviews the recent advancements in the synthesis and applications of LDH based membranes in water purification. The synthesis techniques and the effect of LDH incorporation into different membrane compositions have been described. LDH-based membranes showed excellent antifouling capability and improved water flux due to enhanced hydrophilicity. Such membranes have been successfully used for the treatment of inorganics, organics from environmental water samples. This review will be useful for understanding the current state of the LDH-based membranes for water purification and defining future research dimensions. In the end, we highlight some challenges and future prospects for the efficient application of LDH-based membranes in water decontamination.

A hollow Co9S8 rod-acidified CNT-NiCoLDH composite providing excellent electrochemical performance in asymmetric supercapacitors

Co9S8 and transition metal hydroxides are both potential pseudo-capacitance electrode materials for supercapacitors. Co9S8 has a large specific capacitance and electrochemical activity, and transition metal hydroxides have the advantages of high capacitance and redox activity due to their multiple valence metals and open layered structure. In this study, Co9S8 and NiCoLDH are used to form a Co9S8-aCNT-NiCoLDH composite electrode material by twining acidified carbon nanotubes (aCNTs) around hollow Co9S8 rods and then compounding nickel cobalt hydroxide (NiCoLDH) on the outside. aCNTs provide more electronic channels, which bring more active electrochemical reactions and absorb the volume expansion of Co9S8. The hollow Co9S8 rods and flower-like NiCoLDH structures ensure that the electrode has a highly open structure, which increases the contact area with the electrolyte and is beneficial for ion transport. The outer NiCoLDH can also reduce the volume expansion of Co9S8. These advantages ensure the high specific capacitance and rate performance of the Co9S8-aCNT-NiCoLDH electrode material. Co9S8-aCNT-NiCoLDH was used as the positive material to fabricate asymmetric supercapacitors with attractive energy density and power density, which further proved its excellent electrochemical performance.

Applications of porous frameworks in solid-phase microextraction

Porous frameworks are a term of attracting solid materials assembled by interconnection of molecules and ions. These trendy materials due to high chemical and thermal stability, well-defined pore size and structure, and high effective surface area gained attention to employ as extraction phase in sample pretreatment methods before analytical analysis. Solid-phase microextraction is an important subclass of sample preparation technique that up to now different configurations of this method have been introduced to get adaptable with different environments and analytical instruments. In this review, theoretical aspect and different modes of solid-phase microextraction method are investigated. Different classes of porous frameworks and their applications as extraction phase in the proposed microextraction method are evaluated. Types and features of supporting substrates and coating procedures of porous frameworks on them are reviewed. At the end, the prospective and the challenges ahead in this field are discussed.

One-step facile synthesis of nickel-chromium layered double hydroxide nanoflakes for high-performance supercapacitors

Rational design and synthesis of efficient electrodes with pronounced energy storage properties are crucial for supercapacitors. Herein, we report thin NiCr-layered double hydroxide nanoflakes (NiCr-LDNs) for a high-performance supercapacitor. These fabricated NiCr-LDNs, with various Ni2+/Cr3+ ratios, are one-step controllably synthesized through ultrasonication coupled with mechanical agitation, without hydrothermal treatment or extra exfoliation using organic solvents. Through comparison of different Ni2+/Cr3+ ratios, the Ni2Cr1-LDNs with a 4.7 nm thickness exhibited a superb capacitance performance of 1525 F g-1 at 2 A g-1, which is competitive with most previously reported layered double hydroxide (LDH)-based electrodes. These thin nanoflake structures have the potential to reduce the energy barrier and enhance the capture ability of electrolyte ions. Besides, an asymmetric supercapacitor (ASC) assembled using Ni2Cr1-LDNs achieved a remarkable energy density of 55.22 W h kg-1 at a power density of 400 W kg-1 and maintained high specific capacitance (over 81%), even after 5000 cycles. This work offers an efficient and facile route to fabricating LDH nanoflakes for boosting energy storage capabilities.

Nanoarchitectonics of Nanoporous Carbon Materials in Supercapacitors Applications

High surface area and large pore volume carbon materials having hierarchical nanoporous structure are required in high performance supercapacitors. Such nanoporous carbon materials can be fabricated from organic precursors with high carbon content, such as synthetic biomass or agricultural wastes containing cellulose, hemicellulose, and lignin. Using recently developed unique concept of materials nanoarchitectonics, high performance porous carbons with controllable surface area, pore size distribution, and hierarchy in nanoporous structure can be fabricated. In this review, we will overview the recent trends and advancements on the synthetic methods for the production of hierarchical porous carbons with one- to three-dimensional network structure with superior performance in supercapacitors applications. We highlight the promising scope of accessing nanoporous graphitic carbon materials from: (i) direct conversion of single crystalline self-assembled fullerene nanomaterials and metal organic frameworks, (ii) hard- and soft-templating routes, and (iii) the direct carbonization and/or activation of biomass or agricultural wastes as non-templating routes. We discuss the appealing points of the different synthetic carbon sources and natural precursor raw-materials derived nanoporous carbon materials in supercapacitors applications.

Recent Progress in Two-Dimensional Layered Double Hydroxides and Their Derivatives for Supercapacitors

High-performance supercapacitors have attracted great attention due to their high power, fast charging/discharging, long lifetime, and high safety. However, the generally low energy density and overall device performance of supercapacitors limit their applications. In recent years, the design of rational electrode materials has proven to be an effective pathway to improve the capacitive performances of supercapacitors. Layered double hydroxides (LDHs), have shown great potential in new-generation supercapacitors, due to their unique two-dimensional layered structures with a high surface area and tunable composition of the host layers and intercalation species. Herein, recent progress in LDH-based, LDH-derived, and composite-type electrode materials targeted for applications in supercapacitors, by tuning the chemical/metal composition, growth morphology, architectures, and device integration, is reviewed. The complicated relationships between the composition, morphology, structure, and capacitive performance are presented. A brief projection is given for the challenges and perspectives of LDHs for energy research.

Supercapacitive Performances of Ternary CuCo2S4 Sulfides

Currently, ternary CuCo₂S₄ sulfides are intensively investigated as electrode materials for electrochemical capacitors due to their low cost, high conductivity, and synergistic effect. The research of CuCo₂S₄ materials for energy storage has gradually grown from 2016. The supercapacitive performances of CuCo₂S₄ electrodes for electrochemical capacitors are briefly reviewed in this work. The structure, morphology, and particle size of CuCo₂S₄ are related to the synthesis conditions and electrochemical performances. The thin films of CuCo₂S₄ nanostructures deposited on conductive substrates and their composites both show better properties than single CuCo₂S₄. CuCo₂S₄ and its composites reveal large potential for asymmetric capacitors, delivering high energy densities. However, there is still much new space remaining for future research. The possible development directions, challenges, and opportunities for CuCo₂S₄ materials are also discussed.

The Synthesis of NiCo2O4-MnO2 Core-Shell Nanowires by Electrodeposition and Its Supercapacitive Properties

Hierarchical composite films grown on current collectors are popularly reported to be directly used as electrodes for supercapacitors. Highly dense and conductive NiCo2O4 nanowires are ideal backbones to support guest materials. In this work, low crystalline MnO2 nanoflakes are electrodeposited onto the surface of NiCo2O4 nanowire films pre-coated on nickel foam. Each building block in the composite films is a NiCo2O4-MnO2 core-shell nanowire on conductive nickel foam. Due to the co-presence of MnO2 and NiCo2O4, the MnO2@NiCo2O4@Ni electrode exhibits higher specific capacitance and larger working voltage than the NiCo2O4@Ni electrode. It can have a high specific capacitance of 1186 F·g-1 at 1 A·g-1. When the core-shell NiCo2O4-MnO2 composite and activated carbon are assembled as a hybrid capacitor, it has the highest energy density of 29.6 Wh·kg-1 at a power density of 425 W·kg-1 with an operating voltage of 1.7 V. This work shows readers an easy method to synthesize composite films for energy storage.

Nickel-Based Transition Metal Nitride Electrocatalysts for the Oxygen Evolution Reaction

Electrocatalysis is an efficient and promising means of energy conversion, with minimal environmental footprint. To enhance reaction rates, catalysts are required to minimize overpotential. Alternatives to noble metal electrocatalysts are essential to address these needs on a large scale. In this context, transition metal nitride (TMN) nanoparticles have attracted much attention owing to their high catalytic activity, distinctive electronic structures, and enhanced surface morphologies. Nickel-based materials are an ideal choice for electrocatalysts given nickel's abundance and low cost in comparison to noble metals. In this Minireview, advancements made specifically in Ni-based binary and ternary TMNs as electrocatalysts for the oxygen evolution reaction (OER) are critically evaluated. When used as OER electrocatalysts, Ni-based nanomaterials with 3 D architectures on a suitable support (e.g., a foam support) speed up electron transfer as a result of well-oriented crystal structures and also assist intermediate diffusion, during reaction, of evolved gases. 2 D Ni-based nitride sheet materials synthesized without supports usually perform better than 3 D supported electrocatalysts. The focus of this Minireview is a systematic description of OER activity for state-of-the-art Ni-based nitrides as nanostructured electrocatalysts.

Layered Double Hydroxide-Based Nanomaterials-From Fundamentals to Applications

Layered double hydroxides (LDHs) and their composites with various substances represent an important class of materials suitable for several existing and future applications in biological, chemical, and environmental processes [...].

CoNi2S4 Nanoplate Arrays Derived from Hydroxide Precursors for Flexible Fiber-Shaped Supercapacitors

A high-quality porous CoNi₂S₄ nanoplates array was in situ synthesized on carbon fibers (CFs) by a hydrothermal method via a CoNi-layered double hydroxide (LDH) precursor transformation process. The CoNi₂S₄@CFs electrode exhibits largely enhanced supercapacitor performance with a specific capacitance of 1724 F/g at 1 A/g, in comparison with that of the CoNi-LDH (1302 F/g) precursor. Furthermore, the CoNi₂S₄@CF electrode shows an extremely high rate capability with capacity retention of 79% under a charge density of 60 A/g, whereas the retention rate of CoNi-LDH@CFs is only ∼34%. The abundant pore structure, improved electrical conductivity, and lower internal resistances of CoNi₂S₄@CFs (1.0 Ω) compared to those of CoNi-LDH@CFs (9.5 Ω) are responsible for the enhancement of energy storage performance. By using the CoNi₂S₄ nanoplate array as the positive electrode, an all-solid-state asymmetric fiber-shaped supercapacitor was further obtained, which exhibits outstanding flexible, foldable, and wearable capability. In view of the component tunability for LDH materials, the hydroxide precursor transformation method with merits of mild conditions and easy operation can be extended to the synthesis of a variety of metal sulfides for broad applications in electronic devices.

Design and Regulation of Novel MnFe2O4@C Nanowires as High Performance Electrode for Supercapacitor

Bimetallic oxides have been considered as potential candidates for supercapacitors due to their relatively high electric conductivity, abundant redox reactions and cheapness. However, nanoparticle aggregation and huge volume variation during charging-discharging procedures make it hard for them to be applied widely. In this work, one-dimensional (1D) MnFe₂O₄@C nanowires were in-situ synthesized via a simply modified micro-emulsion technique, followed by thermal treatment. The novel 1D and core-shell architecture, and in-situ carbon coating promote its electric conductivity and porous feature. Due to these advantages, the MnFe₂O₄@C electrode exhibits a high specific capacitance of 824 F·g⁻¹ at 0.1 A·g⁻¹ and remains 476 F·g⁻¹ at 5 A·g⁻¹. After 10,000 cycles, the capacitance retention of the MnFe₂O₄@C electrode is up to 93.9%, suggesting its excellent long-term cycling stability. After assembling with activated carbon (AC) to form a MnFe₂O₄@C//AC device, the energy density of this MnFe₂O₄@C//AC device is 27 W·h·kg⁻¹ at a power density of 290 W·kg⁻¹, and remains at a 10 W·h·kg⁻¹ energy density at a high power density of 9300 W·kg⁻¹.

Use of Co/Fe-Mixed Oxides as Heterogeneous Catalysts in Obtaining Biodiesel

Catalyst-type mixed metal oxides with different compositions and Co/Fe ratios were obtained from layered double hydroxides to be used as heterogeneous catalysts in the production of biodiesel. The effect of the Co/Fe ratio on the precursors of the catalysts was analyzed, considering their thermal, textural and structural properties. The physicochemical properties of the catalysts were determined by thermogravimetric analysis (differential scanning calorimetry and thermogravimetric), X-ray diffraction, Fourier-transform infrared spectroscopy, Scanning Electron Microscopy-Energy Dispersive X-ray spectroscopy and N2-physisorption. The conversion to biodiesel using the different catalysts obtained was determined by diffuse reflectance infrared Fourier-transform spectroscopy and 1H-Nuclear magnetic resonance spectroscopy, allowing us to correlate the effect of the catalyst composition with the catalytic capacity. The conditions for obtaining biodiesel were optimized by selecting the catalyst and varying the percentage of catalyst, the methanol/oil ratio and the reaction time. The catalysts reached yields of conversion to biodiesel of up to 96% in 20 min of reaction using only 2% catalyst. The catalyst that showed the best catalytic activity contains a mixture of predominant crystalline and amorphous phases of CoFe2O4 and NaxCoO2. The results suggest that cobalt is a determinant in the activity of the catalyst when forming active sites in the crystalline network of mixed oxides for the transesterification of triglycerides, with high conversion capacity and selectivity to biodiesel.

Synthesis of NiMoO4/3D-rGO Nanocomposite in Alkaline Environments for Supercapacitor Electrodes

Although Graphene oxide (GO)-based materials is known as a favorable candidate for supercapacitors, its conductivity needs to be increased. Therefore, this study aimed to investigate the performance of GO-based supercapicitor with new methods. In this work, an ammonia solution has been used to remove the oxygen functional groups of GO. In addition, a facile precipitation method was performed to synthesis a NiMoO4/3D-rGO electrode with purpose of using synergistic effects of rGO conductivity properties as well as NiMoO4 pseudocapacitive behavior. The phase structure, chemical bands and morphology of the synthesized powders were investigated by X-ray diffraction (XRD), Raman spectroscopy, and field emission secondary electron microscopy (FE-SEM). The electrochemical results showed that the NiMoO4/3D-rGO(II) electrode, where ammonia has been used during the synthesis, has a capacitive performance of 932 Fg−1. This is higher capacitance than NiMoO4/3D-rGO(I) without using ammonia. Furthermore, the NiMoO4/3D-rGO(II) electrode exhibited a power density of up to 17.5 kW kg−1 and an energy density of 32.36 Wh kg−1. These results showed that ammonia addition has increased the conductivity of rGO sheets, and thus it can be suggested as a new technique to improve the capacitance.

Mechanochemically synthesized MgAl layered double hydroxide nanosheets for efficient catalytic removal of carbonyl sulfide and H2S

Mechanochemically prepared MgAl-LDH nanosheets with high crystallinity and large surface areas show excellent activities in COS hydrolysis and H₂S oxidation.

Interlaced NiMn-LDH nanosheet decorated NiCo2O4 nanowire arrays on carbon cloth as advanced electrodes for high-performance flexible solid-state hybrid supercapacitors

3D hierarchical NiCo₂O₄@NiMn-LDH nanowire/nanosheet arrays have been successfully fabricated on carbon cloth as superior battery-type electrode for high-performance flexible solid-state HSC devices.