Disassembly–Reassembly Approach to RuO2/Graphene Composites for Ultrahigh Volumetric Capacitance Supercapacitor

A porous, yet compact, RuO₂/graphene hybrid is successfully prepared by using a disassembly–reassembly strategy, achieving effective and uniform loading of RuO₂ nanoparticles inside compact graphene monolith. The disassembly process ensures the uniform loading of RuO₂ nanoparticles into graphene monolith, while the reassembly process guarantees a high density yet simultaneously unimpeded ion transport channel in the composite. The resulting RuO₂/graphene hybrid possesses a density of 2.63 g cm⁻³, leading to a record high volumetric capacitance of 1485 F cm⁻³ at the current density of 0.1 A g⁻¹. When the current density is increased to 20 A g⁻¹, it remains a high volumetric capacitance of 1188 F cm⁻³. More importantly, when the single electrode mass loading is increased to 12 mg cm⁻², it still delivers a high volumetric capacitance of 1415 F cm⁻³ at the current density of 0.1 A g⁻¹, demonstrating the promise of this disassembly–reassembly approach to create high volumetric performance materials for energy storage applications.     

Matching CP@NCOH/NF Cathode and GH/FNP/NF Anode for High-Performance Asymmetric Supercapacitor

It is extremely crucial to design and match high-quality cathode and anode for achieving high-performance asymmetric supercapacitors (ASCs). Herein, Co₃(PO₄)₂@NiCo-LDH/Ni foam (CP@NCOH/NF) cathode with hierarchical morphology and graphene hydrogel/Fe–Ni phosphide/Ni foam (GH/FNP/NF) anode with the robust and porous structure are elaborately designed and prepared, respectively. Owing to their unique and profitable structures, both CP@NCOH/NF and GH/FNP/NF electrodes yield the superior capacity (10760 and 2236 mC cm⁻² at 2 mA cm⁻², respectively), good rate capability (63% retention at 200 mA cm⁻² and 52% retention at 50 mA cm⁻², respectively), and excellent cycling stability (72% and 74% retention after 10 000 cycles, respectively). Benefiting from their matchable electrochemical performances, the configured solid-state CP@NCOH/NF//GH/FNP/NF ASC outputs both competitive energy density (80.2 Wh kg⁻¹/4.1 mWh cm⁻³) and power density (14563 W kg⁻¹/750 mW cm⁻³), companied by remarkable cyclability (71% retention after 10 000 cycles), manifesting its great promise for large-scale integrated energy-storage system.     

Highly Compressible Integrated Supercapacitor–Piezoresistance‐Sensor System with CNT–PDMS Sponge for Health Monitoring

Rapid improvement of wearable electronics stimulates the demands for the matched functional devices and energy storage devices. Meanwhile, wearable microsystem requires every parts possessing high compressibility to accommodate large‐scale mechanical deformations and complex conditions. In this work, a general carbon nanotube–polydimethylsiloxane (CNT–PDMS) sponge electrode is fabricated as the elementary component of the compressible system. CNT–PDMS sponge performs high sensitivity as a piezoresistance sensor, which is capable of detecting stress repeatedly and owns great electrochemical performance as a compressible supercapacitor which maintains stably under compressive strains, respectively. Assembled with the piezoresistance sensor and the compressible supercapacitor, such highly compressible integrated system can power and modulate the low‐power electronic devices reliably. More importantly, attached to the epidermal skin or clothes, it can detect human motions, ranging from speech recognition to breathing record, thus showing feasibility in real‐time health monitor and human–machine interfaces.     

NiCo2S4@ACF异质电极材料的绿色制备及其超级电容性能研究

传统的NiCo₂S₄硫化过程需要高温加热, 耗能较大, 并且单纯的硫化物导电性差。本工作通过绿色环保的室温硫化法成功制备出以活性炭纤维(ACF)为核, NiCo₂S₄为壳的复合异质结电极材料(NiCo₂S₄@ACF)。NiCo₂S₄@ACF复合电极材料的层状结构, 有效增大了与电解液的接触面积, 改善了电子的传输路径, 使其具有更优良的电化学性能。当电流密度为1 A/g时, 其比电容值高达1541.6 F/g (678 μF/cm²)。另外, NiCo₂S₄@ACF和ACF分别作正负极组装成的非对称超级电容器(Asymmetric Supercapacitors, ASC)展现了良好的电化学性能: 能量密度高, 当功率密度为800 W/kg时, 能量密度高达49.38 Wh/kg; 循环性能稳定, 循环充放电2000圈后比电容仍能保持90.27%。研究表明, NiCo₂S₄@ACF复合电极材料是一种应用前景广阔的超级电容器电极材料。     

Core–Shell Nitrogen‐Doped Carbon Hollow Spheres/Co3O4 Nanosheets as Advanced Electrode for High‐Performance Supercapacitor

Co₃O₄/nitrogen‐doped carbon hollow spheres (Co₃O₄/NHCSs) with hierarchical structures are synthesized by virtue of a hydrothermal method and subsequent calcination treatment. NHCSs, as a hard template, can aid the generation of Co₃O₄ nanosheets on its surface; while SiO₂ spheres, as a sacrificed‐template, can be dissolved in the process. The prepared Co₃O₄/NHCS composites are investigated as the electrode active material. This composite exhibits an enhanced performance than Co₃O₄ itself. A higher specific capacitance of 581 F g^?1 at 1 A g^?1 and a higher rate performance of 91.6% retention at 20 A g^?1 are achieved, better than Co₃O₄ nanorods (318 F g^?1 at 1 A g^?1 and 67.1% retention at 20 A g^?1). In addition, the composite is employed as a positive electrode to fabricate an asymmetric supercapacitor. The device can deliver a high energy density of 34.5 Wh kg^?1 at the power density of 753 W kg^?1 and display a desirable cycling stability. All of these attractive results make the unique hierarchical Co₃O₄/NHCS core–shell structure a promising electrode material for high‐performance supercapacitors.     

Freestanding 1T‐MnxMo1–xS2–ySey and MoFe2S4–zSez Ultrathin Nanosheet‐Structured Electrodes for Highly Efficient Flexible Solid‐State Asymmetric Supercapacitors

Fabrication of hierarchical nanosheet arrays of 1T phase of transition‐metal dichalcogenides is indeed a critical task, but it holds immense potential for energy storage. A single‐step strategy is employed for the fabrication of stable 1T‐Mn_xMo_1–xS_2–ySe_y and MoFe₂S_4–zSe_z hierarchical nanosheet arrays on carbon cloth as positive and negative electrodes, respectively. The flexible asymmetric supercapacitor constructed with these two electrodes exhibits an excellent electrochemical performance (energy density of ≈69 Wh kg^?1 at a power density of 0.985 kW kg^?1) with ultralong cyclic stability of ≈83.5% capacity retention, after 10 000 consecutive cycles. Co‐doping of the metal and nonmetal boosts the charge storage ability of the transition‐metal chalcogenides following enrichment in the metallic 1T phase, improvement in the surface area, and expansion in the interlayer spacing in tandem, which is the key focus of the present study. This study explicitly demonstrates the exponential enhancement of specific capacity of MoS₂ following intercalation and doping of Mn and Se, and Fe₂S₃ following doping of Mo and Se could be an ideal direction for the fabrication of novel energy‐storage materials with high‐energy storage ability.     

Oxygen Evolution Assisted Fabrication of Highly Loaded Carbon Nanotube/MnO2 Hybrid Films for High‐Performance Flexible Pseudosupercapacitors

To date, it has been a great challenge to design high‐performance flexible energy storage devices for sufficient loading of redox species in the electrode assemblies, with well‐maintained mechanical robustness and enhanced electron/ionic transport during charge/discharge cycles. An electrochemical activation strategy is demonstrated for the facile regeneration of carbon nanotube (CNT) film prepared via floating catalyst chemical vapor deposition strategy into a flexible, robust, and highly conductive hydrogel‐like film, which is promising as electrode matrix for efficient loading of redox species and the fabrication of high‐performance flexible pseudosupercapacitors. The strong and conductive CNT films can be effectively expanded and activated by electrochemical anodic oxygen evolution reaction, presenting greatly enhanced internal space and surface wettability with well‐maintained strength, flexibility, and conductivity. The as‐formed hydrogel‐like film is quite favorable for electrochemical deposition of manganese dioxide (MnO₂) with loading mass up to 93 wt% and electrode capacitance kept around 300 F g^?1 (areal capacitance of 1.2 F cm^?2). This hybrid film was further used to assemble a flexible symmetric pseudosupercapacitor without using any other current collectors and conductive additives. The assembled flexible supercapacitors exhibited good rate performance, with the areal capacitance of more than 300 mF cm^?2, much superior to other reported MnO₂ based flexible thin‐film supercapacitors.     

Spatially Separating Redox Centers on Z‐Scheme ZnIn2S4/BiVO4 Hierarchical Heterostructure for Highly Efficient Photocatalytic Hydrogen Evolution

Photocatalysis technology using solar energy for hydrogen (H₂) production still faces great challenges to design and synthesize highly efficient photocatalysts, which should realize the precise regulation of reactive sites, rapid migration of photoinduced carriers and strong visible light harvest. Here, a facile hierarchical Z‐scheme system with ZnIn₂S₄/BiVO₄ heterojunction is proposed, which can precisely regulate redox centers at the ZnIn₂S₄/BiVO₄ hetero‐interface by accelerating the separation and migration of photoinduced charges, and then enhance the oxidation and reduction ability of holes and electrons, respectively. Therefore, the ZnIn₂S₄/BiVO₄ heterojunction exhibits excellent photocatalytic performance with a much higher H₂‐evolution rate of 5.944 mmol g^?1 h^?1, which is about five times higher than that of pure ZnIn₂S₄. Moreover, this heterojunction shows good stability and recycle ability, providing a promising photocatalyst for efficient H₂ production and a new strategy for the manufacture of remarkable photocatalytic materials.     

Highly Flexible K-Intercalated MnO2/Carbon Membrane for High-Performance Aqueous Zinc-Ion Battery Cathode

The layered MnO₂ is intensively investigated as one of the most promising cathode materials for aqueous zinc-ion batteries (AZIBs), but its commercialization is severely impeded by the challenging issues of the inferior intrinsic electronic conductivity and undesirable structural stability during the charge–discharge cycles. Herein, the lab-prepared flexible carbon membrane with highly electrical conductivity is first used as the matrix to generate ultrathin δ-MnO₂ with an enlarged interlayer spacing induced by the K⁺-intercalation to potentially alleviate the structural damage caused by H⁺/Zn²⁺ co-intercalation, resulting in a high reversible capacity of 190 mAh g⁻¹ at 3 A g⁻¹ over 1000 cycles. The in situ/ex-situ characterizations and electrochemical analysis confirm that the enlarged interlayer spacing can provide free space for the reversible deintercalation/intercalation of H⁺/Zn²⁺ in the structure of δ-MnO₂, and H⁺/Zn²⁺ co-intercalation mechanism contributes to the enhanced charge storage in the layered K⁺-intercalated δ-MnO₂. This work provides a plausible way to construct a flexible carbon membrane-based cathode for high-performance AZIBs.     

Heterojunction‐Assisted Co3S4@Co3O4 Core–Shell Octahedrons for Supercapacitors and Both Oxygen and Carbon Dioxide Reduction Reactions

Expedition of electron transfer efficiency and optimization of surface reactant adsorption products desorption processes are two main challenges for developing non‐noble catalysts in the oxygen reduction reaction (ORR) and CO₂ reduction reaction (CRR). A heterojunction prototype on Co₃S₄@Co₃O₄ core–shell octahedron structure is established via hydrothermal lattice anion exchange protocol to implement the electroreduction of oxygen and carbon dioxide with high performance. The synergistic bifunctional catalyst consists of p‐type Co₃O₄ core and n‐type Co₃S₄ shell, which afford high surface electron density along with high capacitance without sacrificing mechanical robustness. A four electron ORR process, identical to the Pt catalyzed ORR, is validated using the core–shell octahedron catalyst. The synergistic interaction between cobalt sulfide and cobalt oxide bicatalyst reduces the activation energy to convert CO₂ into adsorbed intermediates and hereby enables CRR to run at a low overpotential, with formate as the highly selective main product at a high faraday efficiency of 85.3%. The remarkable performance can be ascribed to the synergistic coupling effect of the structured co‐catalysts; heterojunction structure expedites the electron transfer efficiency and optimizes surface reactant adsorption product desorption processes, which also provide theoretical and pragmatic guideline for catalyst development and mechanism explorations.     

水蒸气二氧化碳共活化制备聚苯胺基活性碳在离子液体超级电容器中的应用

通过水蒸气二氧化碳(H2 O(gas)-CO2)共活化的物理活化方法制备聚苯胺基活性碳被广泛应用于商业活性碳的规模化生产,相比于化学活化方法,该方法制备的活化产物无活化剂残留、 清洗简单且工艺过程环保.以聚苯胺为原料,探究了H2 O(gas)的量和CO2分压对活化产物的影响.采用氮气吸/脱附、 扫描电镜(SEM)、 透...     

One‐Pot Synthesis of Tunable Crystalline Ni3S4@Amorphous MoS2 Core/Shell Nanospheres for High‐Performance Supercapacitors

Transition metal sulfides gain much attention as electrode materials for supercapacitors due to their rich redox chemistry and high electrical conductivity. Designing hierarchical nanostructures is an efficient approach to fully utilize merits of each component. In this work, amorphous MoS₂ is firstly demonstrated to show specific capacitance 1.6 times as that of the crystalline counterpart. Then, crystalline core@amorphous shell (Ni₃S₄@MoS₂) is prepared by a facile one‐pot process. The diameter of the core and the thickness of the shell can be independently tuned. Taking advantages of flexible protection of amorphous shell and high capacitance of the conductive core, Ni₃S₄@amorphous MoS₂ nanospheres are tested as supercapacitor electrodes, which exhibit high specific capacitance of 1440.9 F g^?1 at 2 A g^?1 and a good capacitance retention of 90.7% after 3000 cycles at 10 A g^?1. This design of crystalline core@amorphous shell architecture may open up new strategies for synthesizing promising electrode materials for supercapacitors.     

High‐Performance Asymmetric Supercapacitors Based on Multilayer MnO2/Graphene Oxide Nanoflakes and Hierarchical Porous Carbon with Enhanced Cycling Stability

In this work, MnO₂/GO (graphene oxide) composites with novel multilayer nanoflake structure, and a carbon material derived from Artemia cyst shell with genetic 3D hierarchical porous structure (HPC), are prepared. An asymmetric supercapacitor has been fabricated using MnO₂/GO as positive electrode and HPC as negative electrode material. Because of their unique structures, both MnO₂/GO composites and HPC exhibit excellent electrochemical performances. The optimized asymmetric supercapacitor could be cycled reversibly in the high voltage range of 0–2 V in aqueous electrolyte, which exhibits maximum energy density of 46.7 Wh kg^?1 at a power density of 100 W kg^?1 and remains 18.9 Wh kg^?1 at 2000 W kg^?1. Additionally, such device also shows superior long cycle life along with ～100% capacitance retention after 1000 cycles and ～93% after 4000 cycles.