Electroactive Sites Research Articles

Interface engineering of a hollow core-shell sulfur-doped Co2P@Ni2P heterojunction for efficient charge storage of hybrid supercapacitors

Transition metal phosphides (TMPs) are widely used as supercapacitor energy storage materials due to their abundant valence and high theoretical capacity, but their poor electrical conductivity and low active material utilization lead to low actual capacity and slow kinetics. Herein, we demonstrate the excellent electrochemical properties of sulfur-doped Co2P@Ni2P heterojunction materials prepared using a combination of hydrothermal, ion-exchange and low-temperature annealing approaches. For sulfur-doped Co2P@Ni2P, hollow core-shell microstructures increase the number of electroactive sites and provides a shortcut for electron transport, while sulfur doping promotes the transfer and rearrangement of interfacial charge from Co2P to Ni2P, optimizing the redox ability of the active component. In addition, the S doping and the highly electrochemically active nickel-cobalt phosphide synergistically accelerate the charge transfer, which leads to fast reaction kinetics. Therefore, the obtained S-Co2P@Ni2P exhibits an optimal specific capacity of 1200 C g−1 at 1 A g−1 and excellent rate performance. Furthermore, when combined with activated carbon (AC) for hybrid supercapacitor (HSC), the S-Co2P@Ni2P//AC device shows an excellent energy density of 41.5 Wh kg−1 and a high-capacity retention of 93 % after 15,000 cycles. This work provides a novel approach for the exploration of high-performance and stable phosphorus-based battery-like supercapacitor materials.

Highly Sensitive and Selective Dopamine Determination in Real Samples Using Au Nanoparticles Decorated Marimo-like Graphene Microbead-Based Electrochemical Sensors

A sensitive and selective electrochemical dopamine (DA) sensor has been developed using gold nanoparticles decorated marimo-like graphene (Au NP/MG) as a modifier of the glassy carbon electrode (GCE). Marimo-like graphene (MG) was prepared by partial exfoliation on the mesocarbon microbeads (MCMB) through molten KOH intercalation. Characterization via transmission electron microscopy confirmed that the surface of MG is composed of multi-layer graphene nanowalls. The graphene nanowalls structure of MG provided abundant surface area and electroactive sites. Electrochemical properties of Au NP/MG/GCE electrode were investigated by cyclic voltammetry and differential pulse voltammetry techniques. The electrode exhibited high electrochemical activity towards DA oxidation. The oxidation peak current increased linearly in proportion to the DA concentration in a range from 0.02 to 10 μM with a detection limit of 0.016 μM. The detection selectivity was carried out with the presence of 20 μM uric acid in goat serum real samples. This study demonstrated a promising method to fabricate DA sensor-based on MCMB derivatives as electrochemical modifiers.

Anti-stacking synthesis of MXene-reduced graphene oxide sponges for aqueous zinc-ion hybrid supercapacitor with improved performance

Two‑dimensional MXenes with an enormous active surface area are considered to be significant cathode materials for Zn‑ion hybrid supercapacitors. However, the nanosheets are easily self-restacked during the assembly into macroscopic porous electrodes, resulting in a significantly reduced effective surface area, hindering their applications in energy storage. Here, MXenes are subtly distributed on the surface of the sponge in a coral-like structure rather than participating in the assembly of the framework, which has suppressed the self-restacking of MXene effectively, improved the hydrophilicity of the sponge, and provided fast diffusion channels for electrolyte ions. Therefore, the MXene-TiC-reduced graphene oxide sponge exhibits excellent electrical conductivity, an enormous specific surface area with abundant accessible electroactive sites, and superior electrochemical performance. The resulting sponge demonstrates an outstanding specific capacity, up to 501 mAh g–1 at 0.2 A g–1, with excellent capacity retention (90%) after 3100 cycles as Zinc-ion hybrid supercapacitor cathodes. Furthermore, it exhibits an elegant gravimetric energy density of 486 mWh g–1 at 415 mW g–1, which has surpassed most leading MXene-based Zn-ion cathodes. This work provides a new synthetic idea for MXene-based macro-composites and paves a new avenue for designing next-generation flexible and portable porous electrodes with high gravimetric and rate performances.

Hetero-interface-engineered sulfur vacancy and oxygen doping in hollow Co9S8/Fe7S8 nanospheres towards monopersulfate activation for boosting intrinsic electron transfer in paracetamol degradation

Designing defects-rich hollow heterostructure bimetal sulfides is considered as an efficient strategy for accelerated monopersulfate (MPS) activation. Herein, mono-step sulfidation was employed to develop sulfur vacancy (SV)-rich hollow oxygen-doped Co9S8/Fe7S8 (O-CSFS). SV and oxygen doping-induced highly electroactive sites, low charge resistance, and increased conductivity of O-CSFS accounted for its superior performance. Reactive oxygen species (ROS)-driven pathway and electron transfer (ET)-driven pathway were revealed to be responsible for PCM degradation in O-CSFS/MPS system, but the role of ET-driven pathway was more significant. The ROS-driven pathway was mainly attributed to electrons-rich low valance of Co atoms which activated MPS to generate different ROS without •OH contribution and with a greater role of SO4•− than 1O2. Doped O, S species, and surface-active O-CSFS/MPS complex in ET-driven pathway, meanwhile, acquired electrons from PCM, resulting in enhanced PCM oxidation. This study provided more insight into ET-enhanced efficient PCM degradation induced by SV and oxygen-doping.

Layered Metal Oxide Nanosheets with Enhanced Interlayer Space for Electrochemical Deionization.

Electrochemical deionization is regarded as one of the promising water treatment technologies. Here, CoAl-layered metal oxide nanosheets intercalated by sodium dodecyl sulfate (SDS) with an enhanced interlayer spacing from 0.76 to 1.33nm are synthesized and used as an anode. The enlarged interlayer spacing provides an enhanced ion-diffusion channel and improves the utilization of the interlayer electroactive sites, while heat treatment, transferring layered double hydroxides to layered metal oxides (LMOs), offers additional active oxidation reaction sites to facilitate the electro-sorption rate, contributing to the high salt adsorption capacity (31.78mgg-1 ) and average salt adsorption rate (3.75mgg-1 min-1 ) at 1.2V in 500mgL-1 NaCl solution. In addition, the excellent long-term cycling stability (92.9%) after 40 cycles proves the strong electronic interaction between SDS and the host layer, which is validated by density functional theory calculations later on. Moreover, the electro-sorption mechanism of LMOs that originated from the reconstruction of the layered structure based on the "memory effect" is revealed according to the X-ray photoelectron spectroscopy peak shifts of Co element. This strategy of expanding the interlayer spacing combined with heat treatment makes LMOs a competitive candidate for electrochemical water deionization.

Optimization and Fabrication of Binder-Free Nickel-Copper Phosphate Battery-type Electrode Using Microwave-Assisted Hydrothermal Method

In this study, a binder-free nickel-copper phosphate battery-type electrode was fabricated using a microwave-assisted hydrothermal technique. The fabrication process was optimized with Design of Experiment (DoE) software and then validated experimentally. The electrode made at 90 °C for 12.5 min, with a Ni:Cu precursor ratio of 3:1, had the highest specific capacity. The experimental specific capacity of the optimized nickel-copper phosphate (Ni3-Cu-P) binder-free electrode was 96.2% of the theoretical value predicted by the software, which was within 10% error. Moreover, the growth of amorphous Ni3-Cu-P electrode material with irregular microspheres of small size was observed on the surface of nickel foam. These amorphous microspherical shapes of the Ni3-Cu-P electrode material provide more electroactive sites and a larger active surface area for faradaic reaction. In electrochemical energy storage applications, the Ni3-Cu-P electrode outperformed the bare Ni-P and Cu-P electrodes, with the highest areal capacity (0.77 C cm−2), the lowest charge transfer resistance (81.7 Ω), and the highest capacity retention (83.9%) at 2.0 mA cm−2. The study indicates that the Ni3-Cu-P electrode’s exceptional electrochemical properties result from the interaction between nickel and copper in the binary metal phosphate framework, making it an excellent choice for battery-type electrodes used in electrochemical energy storage applications.

Multicomponent Intermetallic Nanoparticles on Hierarchical Metal Network as Versatile Electrocatalysts for Highly Efficient Water Splitting

AbstractDeveloping high‐efficiency and cost‐effective alloy catalysts toward hydrogen‐evolution reaction (HER) is crucial for large‐scale hydrogen production via electrochemical water splitting, but conventional single‐principal‐element alloy design usually causes insufficient activity and durability of state‐of‐the‐art multimetallic catalysts based on non‐precious transition metals. Herein, we report multicomponent intermetallic Mo(NiFeCo)4 nanoparticles seamlessly integrated on hierarchical nickel network (Mo(NiFeCo)4/Ni) as robust hydrogen‐evolution electrocatalysts with remarkably improved activity and durability by making use of iron and cobalt atoms partially substituting nickel sites to form high‐entropy NiFeCo sublattice in intermetallic MoNi4 matrix, which serve as bifunctional electroactive sites for both water dissociation and adsorption/combination of hydrogen intermediate and improves thermodynamic stability. By virtue of bicontinuous nanoporous nickel skeleton facilitating electron/ion transportation, self‐supported nanoporous Mo(NiFeCo)4/Ni electrode exhibits exceptional HER electrocatalysis, with low Tafel slope (≈35 mV dec−1), high current density (≈2300 mA cm−2) at low overpotential (200 mV) and long‐term durability in 1 m KOH. When coupled to its electrooxidized and nitrified derivative for oxygen‐evolution reaction, their alkaline water electrolyzers operate with a superior overall water‐splitting output, outperforming the one constructed with commercially available noble‐metal‐based catalysts. These electrochemical properties make it an attractive candidate as electrocatalyst in alkaline water electrolysis for large‐scale hydrogen generation.

Controllable 3D Flower-Like Ag-CF Electrodes as Flexible Marine Electric Field Sensors with High Stability

Construction of three-dimensional (3D) flower-like nanostructures with controlled morphologies has emerged as an attractive tool by scientists in the marine electric field sensor research field due to their peculiar structural features. Herein, novel 3D flower-like Ag-CF capacitive composite electrodes have been created by an eco-friendly water-bath strategy via AgNO3 as a sliver source and subsequently compounded with carbon fibers (CFs) pretreated by thermal oxidation. A series of electrode samples with various morphologies obtained by modulating different reaction times and temperatures bring about the dominant formation mechanism of these nanostructures and the influence behavior on the CF electrode in detail. Especially, the 3D flower-like Ag-CF electrode shows a large surface area acquired under the conditions of 80 °C and 15 min, which can provide more electroactive sites in electrochemical analysis and exhibit a maximum areal specific capacitance of 619.75 mF·cm-2 at a scanning speed of 10 mV·s-1. This is mainly due to the synergistic behavior of the unique 3D flower-like morphology and the large specific surface area of CFs. Furthermore, a cylinder-shaped Ag-CF sensor is designed, which delivers a superior potential difference of 33.08 μV, a potential difference drift of 18.62 μV/24 h for 30 days, and a self-noise of 0.92 nV/rt (Hz)@1 Hz. In this work, the intriguing synthesis strategy can be a promising facile approach to manufacture the controllable 3D flower-like Ag-CF electrode for electric field sensor applications.

Facile Construction of Porous ZnMn2O4 Hollow Micro-Rods as Advanced Anode Material for Lithium Ion Batteries.

Spinel ZnMn2O4 is considered a promising anode material for high-capacity Li-ion batteries due to their higher theoretical capacity than commercial graphite anode. However, the insufficient cycling and rate properties seriously limit its practical application. In this work, porous ZnMn2O4 hollow micro-rods (ZMO HMRs) are synthesized by a facile co-precipitation method coupled with annealing treatment. On the basis of electrochemical analyses, the as-obtained samples are first characterized by X-ray diffraction, X-ray photoelectron spectroscopy, transmission electron microscopy, and scanning electron microscopy techniques. The influences of different polyethylene glycol 400 (PEG 400) additions on the formation of the hollow rod structure are also discussed. The abundant multi-level pore structure and hollow feature of ZMO HMRs effectively alleviate the volume expansion issue, rendering abundant electroactive sites and thereby guaranteeing convenient Li+ diffusion. Thanks to these striking merits, the ZMO HMRs anode exhibits excellent electrochemical lithium storage performance with a reversible specific capacity of 761 mAh g-1 at a current density of 0.1 A g-1, and a long-cycle specific capacity of 529 mAh g-1 after 1000 cycles at 2.0 A g-1 and keep a remarkable rate capability. In addition, the assembled ZMO HMRs-based full cells deliver an excellent rate capacity, and when the current density returns to 0.05 A g-1, the specific capacity can still reach 105 mAh g-1 and remains at 101 mAh g-1 after 70 cycles, maintaining a material-level energy density of approximately 273 Wh kg-1. More significantly, such striking electrochemical performance highlights that porous ZMO HMRs could be a promising anode candidate material for LIBs.

Impact of Co-doping on the microstructural and electrochemical features of mesoporous 3D oval–shaped Ni3-xCoxV2O8 electrodes for high-performance hybrid supercapacitors

Transition metal vanadates have sparked much attention as positive electrode materials for supercapacitors; nevertheless, their poor electronic conductivity, low electroactive sites, and sluggish charge transfer kinetics continue to be problematic. Herein, we incorporate Co dopants in nickel vanadates (NCV) and successfully tailor porous 3D oval-shaped particles using hydrothermal synthesis at 210 °C for 12 h. The interconnected particles, as well as the porous nature of each oval-shaped particle, provide high accessibility to active species and improve charge transfer kinetics. Additionally, the incorporation of cobalt dopants improves electronic conductivity and enriches redox chemistry. As a consequence, NCV delivered a specific capacitance of 391/376 F/g at 0.5/1 A/g current density, with capacitance retention of 98.6 % after 8000 cycles, indicating outstanding cycling stability. Moreover, the micro-spherical layered-structured BiOBr electrode was chosen for the negative electrode and demonstrated a specific capacitance of 132 F/g at a current density of 1 A g−1, in the potential window of −1 to +0 V. Furthermore, the solid-state Ni3-xCoxV2O8//BiOBr hybrid supercapacitor device demonstrated 118 F/g specific capacitance, 25.5 Wh kg−1 energy density, and exceptional cycle stability (85.9 % capacitance preserved after 10,000 cycles).

Hierarchical porous N-doped functionalized reduced graphene oxide by 2-aminoanthraquinone for aqueous zinc-ion hybrid capacitors with high energy density and ultralong-life

Designing and synthesizing organic-based composite electrode with the advantages of abundant resources, low-cost, light-weight, and high performance is one of the key factors for renewable energy storage with intermittent and unstable features, and still has far-reaching significance and challenge. Herein, we successfully synthesized nanostructured hierarchical porous N-doped functionalized reduced graphene oxide by 2-aminoanthraquinone (N-RGO/AAQs) composites via a facile solvothermal method. Introducing N-doping and AAQ organic molecules not only provide more capacity and better wettability, but also help to reduce the agglomeration of RGO nanosheets and obtain more abundant exposed electroactive sites. Coupled with the good conductivity of RGO and the constructed network channels that facilitate the rapid diffusion and transport of ions/electrons, the obtained novel N-RGO/AAQs composite electrodes exhibit excellent electrochemical performance. The aqueous zinc-ion hybrid capacitor assembled with N-RGO/AAQ cathode and metal Zn anode also delivers a high specific capacity of 142.9 mAh g−1 at 0.6 A g−1, an enhanced energy density of 122.9 Wh kg−1 and an ultra-long cycling life of 93.3 % capacity retention after 12,000 cycles. This novel nanostructured organic-based functionalized RGO composite as the cathode is a promising alternative for sustainable high-performance energy storage devices with low-cost, high-safety, light-weight and high-flexibility.

Aligned silver nanoparticles anchored on pyrrolic and pyridinic-nitrogen induced carbon nanotubes for enhanced oxygen reduction reaction

Comprehension of the metal-nanostructure arrays is of great significance for the rational design of the cathode catalyst for the oxygen reduction reaction (ORR). Therefore, we fabricated a cathode catalyst consisting of the small-size, aligned silver nanoparticles (Ag NPs) embedded into the pyrrolic and pyridinic-Nitrogen functionalized carbon nanotubes. The N-defected structure was prepared by acidification of carbon nanotubes (CNTs) to avoid inherited stacking of its layers followed by the introduction of 2,7 diaminophenazine (DPA) using a hydrothermal process, while small-size Ag NPs were aligned through electrodeposition onto the N-defected carbon nanotube (CNT-DPA-Ag). The individual role of pyrrolic and pyridinic -N in the electrocatalytic ORR performance, synthesis of small size, and distribution behavior of Ag NPs were evaluated. To maximize the ORR performance of the catalyst, the advantage was taken from the presence of carbon atoms next to the pyridinic-N which is a Lewis base and acts as an adsorption and protonation site for the oxygen (O2) molecule and eventually ensures a direct 4e− transfer route for the electrochemical conversion of O2 into water (H2O). Transmission electron microscopy (TEM) analysis of CNT-DPA-Ag revealed a small size, aligned Ag NPs (average size 2 nm) resulting in a large surface area and rich electroactive sites for adsorption of O2. The CNT-DPA-Ag showed a remarkable ORR performance in terms of positive onset potential (-0.052 V), high diffusion-limiting current density (-5.54 mAcm−2), and noteworthy methanol tolerance, and long-term durability in comparison to the commercial 20 wt% Pt/C.

NiCo2S4 combined 3D hierarchical porous carbon derived from lignin for high-performance supercapacitors

Metal sulfides with the nature of low electronegativity and high electrochemical activity are potentially considered effective electrode materials for supercapacitors. Meanwhile, hierarchical porous carbon (HPC) materials derived from eco-friendly enzymatic hydrolysis lignin are the ideal matrix for holding nanoparticles (NP) that allows the overall NP/HPC composite to achieve outstanding electrochemical performance. In this study, NiCo2S4 nanoparticles were in-situ synthesized on the inner surface of 3D HPC that derived from enzymatic hydrolysis lignin with a simple one-step solvothermal method, thus forming a high-performance composite electrode material for supercapacitor applications. As a result, the NiCo2S4/HPC composite yields an outstanding specific capacity of 1264.2 F g−1 at 1 A g−1 and also exhibits remarkable rate performance. Such remarkable property is attributed to the effective combination of NiCo2S4 plus HPC and their strong chemical bonds, which enable excellent electronic conductivity and abundant exposed electroactive sites. The asymmetric supercapacitor assembled by utilizing NiCo2S4/HPC and active carbon as the positive and negative electrodes, respectively, provide an excellent energy density of 32.05 Wh kg−1 at a power density of 193.9 W kg−1. This work puts forward a practical optimization strategy for metal sulfides used in electrochemical energy storage devices.

Facile Hydrothermal Fabrication of an α-Ni(OH)2/N-Doped Reduced Graphene Oxide Nanohybrid as a High-Performance Anode Material for Lithium-Ion Batteries

Metal hydroxides are a kind of promising anode materials for lithium-ion batteries (LIBs) because of their large theoretical capacity, easy preparation, and low cost. However, their application has been restricted by cycling instability and slow kinetics arising from large volume variation and poor conductivity. Herein, a nanostructured α-Ni(OH)2/N-doped reduced graphene oxide (NrGO) hybrid is fabricated through a hydrothermal approach. This Ni(OH)2/NrGO hybrid exhibits high reversible capacity (1220 mA h g–1 at 0.2 A g–1), superior cyclability, and superb rate ability (559 mA h g–1 at 10 A g–1). The excellent electrochemical performance benefits from the hybrid nanostructure, which inhibits the agglomeration of active nanoparticles, exposes more electroactive sites, inhibits the restacking of NrGO sheets, and retains mechanical integrity during cycling. Besides, the highly conductive NrGO sheets provide efficient transport pathways for electrons and further enhance the electrochemical kinetics. When paired with the LiCoO2 cathode, this Ni(OH)2/NrGO hybrid displays a stable capacity in a full cell, demonstrating its promising practicability in LIBs.

Microwave-Assisted Hierarchically Grown Flake-like NiCo Layered Double Hydroxide Nanosheets on Transitioned Polystyrene towards Triboelectricity-Driven Self-Charging Hybrid Supercapacitors.

Recently, there is a need to explore the utilization of various heterostructures using the designed nanocomposites and tuning the surfaces of electrodes for improving the electrochemical performance of supercapacitors (SC). In this work, a novel approach is successfully employed through a facile two-step synthetic route with the assistance of a microwave for only 1 min. Depending on the glass transition of a polystyrene (PS) substrate and electrochemical deposition (ECD) of electroactive Ni-Co layered double hydroxides (LDHs), a hierarchically designed flake-like morphology can be readily prepared to enhance the surface-active sites, which allows a rhombohedral Ni-Co LDHs electrode to obtain superior electrochemical properties. Further, the interactions between electrode and electrolyte during the diffusion of ions are highly simplified using multiple enhanced electroactive sites and shorter pathways for electron transfer. The unique surface architecture of the PS substrate and the synergistic effect of the bimetallic components in Ni-Co LDHs enable this substrate to obtain desired electrochemical activity in charge storage systems. The optimized MWC Co0.5Ni0.5 electrode exhibited an areal capacity of 100 µAh/cm2 at a current density of 1 mA/cm2 and a remarkable capacity retention of 91.2% over 5000 continuous charging and discharging cycles due to its remarkable synergistic effect of abundant faradaic redox reaction kinetics. The HSC device is assembled with the combination of optimized MWC Co0.5Ni0.5 and activated carbon as a positive and negative electrode, respectively. Further, the electrochemical test results demonstrated that MWC Co0.5Ni0.5 //AC HSC device showed a high areal capacitance of 531.25 mF/cm2 at a current density of 5 mA/cm2. In addition, the fabricated an aqueous HSC device showed a power density of 16 mW/cm2 at an energy density of 0.058 mWh/cm2, along with the remarkable capacity retention of 82.8% even after 10,000 continuous charging and discharging cycles. Moreover, the assembled hybrid supercapacitor (HSC) device is integrated with a triboelectric nanogenerator (TENG) for the development of energy conversion and storage systems. Not only an extensive survey of materials but also an innovative solution for recent progress can confirm the wide range of potential SC applications. Remarkably, this study is a new way of constructing self-powered energy storage systems in the field of sustainable wearable electronics and future smart sensing systems.

Graphitic Carbon Nitride Nanosheets Decorated with Strontium Tungstate Nanospheres as an Electrochemical Transducer for Sulfamethazine Sensing

Sulfamethazine (SMZ) is one of the most frequently utilized sulfonamides, and it is regularly found in animal-derived foods, posing a health risk. Hence, developing a quick, easy, selective, and sensitive analytical method for on-site detection of SMZ is essential for improving food safety. Recently, transition-metal oxides have attracted great interest as promising sensors for detecting sulfamethazine due to their superior redox behavior, electrochemical activity, and electroactive sites. However, they tremendously suffer from poor electrical conductivity and electrochemical stability, which limits their commercial reality. Herein, a highly selective sensor consisting of two-dimensional (2D) graphitic carbon nitride nanosheet (g-C3N4) networks anchored to strontium tungstate nanospheres (denoted as SrWO4/g-C3N4) is developed for nonenzymatic sulfamethazine detection. When employed as the sensing platform, the SrWO4/g-C3N4 hybrid shows enhanced sensing performance with a fast response time, high sensitivity, low detection limit of 0.0059 μM, wide detection ranges from 0.2 to 600 μM, and prolonged cycle life of over 30 days. The sensor performs well in sulfamethazine in real sample analysis, reflecting its practical applicability. Such a performance may be attributed to the numerous electroactive sites, confined electronic structures, and high synergistic interaction between active SrWO4 species and the g-C3N4 matrix. This work demonstrates an innovative protocol for developing SrWO4/g-C3N4-based sensing platforms with nanoscale architectures and high interface configurations.

Scalable synthesis of Ta1.1O1.05/biomass carbon composite with multiple structure engineering by boron-doped graphene quantum dot for high-energy supercapacitor

Low intrinsic conductivity and insufficient electroactive sites hinder wide applications of tantalum oxide in supercapacitors. The study reports scalable synthesis of Ta1.1O1.05/biomass carbon (C) composite with multiple structure engineering by boron-doped graphene quantum dot (B-GQD). B-GQD was orderly coordinated with Ta(V) ion to produce Ta-B-GQD complex, sucked into cotton and dried. Followed by annealing at 900 °C in N2 to obtain B-GQD-Ta1.1O1.05/C. Experimental result and theoretical calculation demonstrate that the introduction of B-GQD results in formation of Ta1.1O1.05 nanorods with low valence, small size, highly exposed high-index crystal faces, oxygen vacancies and PN junction. The structure dramatically improves the intrinsic conductivity, electroactive sites and voltage window range. The B-GQD-Ta1.1O1.05/C electrode exhibits high capacitance of 528.3 F g−1 at 0.5 A/g, which is more than that of Ta1.1O1.05 electrode (130.9 F g−1). The flexible symmetrical supercapacitor provides ultrahigh capacitance of 374.1 F g−1 at 1 A/g, high-rate capacity of 207.8 F g−1 at 50 A/g, capacity retention of 98.7 % after 10,000 cycles at 10 A/g and energy density of 113.9 W h Kg−1 at 521.2 W kg−1. The supercapacitor has been successfully applied in the self-powered attitude sensor driven via friction nanogenerator to monitor human walking posture.

Dual regulation strategy to enhance the electrochemical performance of rich sulfur vacancies NiCo2S4 integrate electrode material for supercapacitors

NiCo2S4 is a promising electrode material for supercapacitors due to its high conductivity and rich elemental valence distribution. However, the low specific capacitance and poor cycling stability of NiCo2S4 electrode material restricted its practical application. In this paper, we proposed a dual regulation strategy of nitrogen-doped carbon cloth current collector (NCC) and the introduction of S vacancies in the NiCo2S4 (NCS) to prepare a high electrochemical performance of integrated electrode material. The introduction of N doping into the CC current collector helped to improve the loading capacity of NCS and contributed to capacitance, while the rich S vacancies in NCS could provide more electroactive sites and increase its electrical conductivity. Benefiting from the synergistic effect of NCC and S vacancies, the fabricated NCS4–0.5/NCC integrated electrode material illustrated an ultra-high specific capacitance of 4075.89 mF cm−2 (2079.53 F g−1) at 1 mA cm−2 and superior electrochemical cycling stability with 80.03% of initial capacitance at a high current density of 20 mA cm−2 after 5000 cycles. Therefore, the present dual regulation strategy provides a new route to fabricate supercapacitor electrode materials with excellent electrochemical properties.

Rational design of CoP@Ni(OH)2 bilayer nanosheets for high-performance supercapacitors

The CoP@Ni(OH)2 bilayer nanosheets can provide abundant transport paths for electrons and ions, expose more electroactive sites, and enhance structural stability.

Zincophilic multilayer graphene structures leveraging fast and ultrastable Zn-ion storage

Zincophilic multilayer graphene structurein situconstructed to glue more electroactive sites and opposite charge-carrier uptake entails alternate binding of Zn2+/CF3SO3−at active sites.