Influence of synthesized functionalized reduced graphene oxide aerogel with 4,4′-methylenedianiline as reducing agent on electrochemical and pseudocapacitance performance of poly orthoaminophenol electroactive film

Biomimetic biomass-based composite carbon aerogels with excellent mechanical performance for energy storage and pressure sensing in extreme environments

The poor mechanical properties of biomass-based carbon aerogels after carbonization severely limit their application in pressure sensing and energy storage for wearable devices and electronic skin. In this work, a supramolecular assembly structure was designed inspired by the unique microstructure of natural wood for the preparation of biomass-based carbon aerogels with supercompressibility, elasticity, stable strain electrical signal response, and wide sensitive detection. Bacterial cellulose and lignin were selected as the main components of the biomass-based composite aerogel 'cell wall'. The graphene oxide with an aromatic structure was introduced to induce the assembly of firmly attached lignin and bacterial cellulose. The prepared biomass-based carbon aerogels exhibit supercompressibility (at least 100 cycles at 90 % strain), high elasticity (88.88 % height retention after 1000 cycles at a strain of 50 %), surprising temperature-constant superelasticity and fatigue resistance (shape retention rate greater than 85 %) at -196 ℃. In particular, it exhibits temperature-invariant high linear sensitivity over an extremely wide operating pressure range (0-43 kPa), allowing accurate detection of human signals. In addition, the prepared carbon aerogels exhibit excellent performance in supercapacitors. It has a specific capacitance of 158F/g at a current density of 1 A/g and an energy density of 18.75 Wh/kg at a high power density of 2500 W/g. This strategy also demonstrates its promise as a wearable device in hostile environments.

Fabrication and Advanced Imaging Characterization of Magnetic Aerogel-Based Thin Films for Water Decontamination

Aerogels have emerged as appealing materials for various applications due to their unique features, such as low density, high porosity, high surface area, and low thermal conductivity. Aiming to bring the advantages of these materials to the environmental field, this study focuses on synthesizing magnetic silica aerogel-based films suitable for water decontamination. In this respect, a novel microfluidic platform was created to obtain core-shell iron oxide nanoparticles that were further incorporated into gel-forming precursor solutions. Afterward, dip-coating deposition was utilized to create thin layers of silica-based gels, which were further processed by 15-hour gelation time, solvent transfer, and further CO2 desiccation. A series of physicochemical analyses (XRD, HR-MS FT-ICR, FT-IR, TEM, SEM, and EDS) were performed to characterize the final films and intermediate products. The proposed advanced imaging experimental model for film homogeneity and adsorption characteristics confirmed uniform aerogel film deposition, nanostructured surface, and ability to remove pesticides from contaminated water samples. Based on thorough investigations, it was concluded that the fabricated magnetic aerogel-based thin films are promising candidates for water decontamination and novel solid-phase extraction sample preparation.

Dynamics of reduced graphene oxide: synthesis and structural models

Technological advancements are leading to an upsurge in demand for functional materials that satisfy several of humankind's needs. In addition to this, the current global drive is to develop materials with high efficacy in intended applications whilst practising green chemistry principles to ensure sustainability. Carbon-based materials, such as reduced graphene oxide (RGO), in particular, can possibly meet this criterion because they can be derived from waste biomass (a renewable material), possibly synthesised at low temperatures without the use of hazardous chemicals, and are biodegradable (owing to their organic nature), among other characteristics. Additionally, RGO as a carbon-based material is gaining momentum in several applications due to its lightweight, nontoxicity, excellent flexibility, tuneable band gap (from reduction), higher electrical conductivity (relative to graphene oxide, GO), low cost (owing to the natural abundance of carbon), and potentially facile and scalable synthesis protocols. Despite these attributes, the possible structures of RGO are still numerous with notable critical variations and the synthesis procedures have been dynamic. Herein, we summarize the highlights from the historical breakthroughs in understanding the structure of RGO (from the perspective of GO) and the recent state-of-the-art synthesis protocols, covering the period from 2020 to 2023. These are key aspects in the realisation of the full potential of RGO materials through the tailoring of physicochemical properties and reproducibility. The reviewed work highlights the merits and prospects of the physicochemical properties of RGO toward achieving sustainable, environmentally friendly, low-cost, and high-performing materials at a large scale for use in functional devices/processes to pave the way for commercialisation. This can drive the sustainability and commercial viability aspects of RGO as a material.

Hierarchical nanocomposite of carbon-fiber-supported NiCo-based layered double-hydroxide nanosheets decorated with (NiCo)Se2 nanoparticles for high performance energy storage

Exploring novel structures consisting of multiple highly active components is a crucial challenge for supercapacitor applications. Using an in-situ self-templated method, we demonstrate the controlled fabrication of a fibrous hierarchical nanocomposite made of carbon microfibers covered with a layer of metal-organic framework (MOF) derived from nickel-cobalt layered double-hydroxide (NiCo-LDH) nanosheets decorated with (NiCo)Se₂ nanoparticles. The (NiCo)Se₂ nanoparticles attached tightly onto the surface of the two-dimensional NiCo-LDH, both of which were generated by the decomposition of the NiCo-based MOF, and exhibited multiple active sites that contributed to improved electrical conductivity, high capacity, and structural stability. Density functional theory calculations revealed that the density of states near the Fermi level was significantly enhanced, favoured OH^- adsorption, and promoted the kinetics of the electrochemical reaction. Benefiting from the intrinsic synergetic contributions from the hierarchical nanoscale structure, the electrode made from the nanocomposite delivered an impressive capacity of 1394.2 F g^-1 (702.7 C g^-1) at 1 A g^-1. Furthermore, a hybrid supercapacitor based on the developed nanocomposite demonstrated an energy density of 50.6 W h kg^-1 and a power density of 800 W kg^-1 with high cyclic stability. Our results suggest that the hierarchical nanocomposite can be a powerful electrode for advanced next-generation supercapacitors.

Regulating monomer assembly to enhance PEDOT capacitance performance via different oxidants

The development of poly(3,4-ethylenedioxythiophene) (PEDOT) with high specific capacitance is the key to pursuing high-performance supercapacitors, and the electrochemical properties of PEDOT are closely related to the oxidation degree and conjugated chain length of its molecular chain. In this work, the influences of various oxidants (FeCl₃, Fe(Tos)₃ and MoCl₅) on the molecular chain structure and capacitive properties of PEDOT via vapor phase polymerization were systematically investigated. Fe(Tos)₃ can significantly improve the degree of oxidation and the length of the conjugated chain of PEDOT compared to FeCl₃ and MoCl₅, enhancing the conductivity and providing more active sites for Faraday reaction. Therefore, the PEDOT/P(Fe(Tos)₃) electrode displays a considerable conductivity of 73 S cm^-1, high areal capacitance (419 mF cm^-2) and excellent electrochemical stability under the different bent state. Moreover, the conjugated structure strengthens the interaction between PEDOT chains, achieving good cycle stability. Therefore, Fe(Tos)₃ is an ideal oxidant for obtaining high-performance PEDOT electrode materials.

Heterogeneous iron oxide nanoparticles anchored on carbon nanotubes for high-performance lithium-ion storage and fenton-like oxidation

In this work, heterogeneous hematite (Fe₂O₃) and magnetite (Fe₃O₄) nanoparticles are jointly engineered on the external surface of multi-walled carbon nanotubes (CNTs) to construct a composite material (Fe₂O₃@Fe₃O₄/CNT). A simple one-step redox reaction is triggered in a hydrothermal reaction system containing functionalized CNT (FCNT) aqueous suspension and iron foils. Both Fe₂O₃ and Fe₃O₄ nanoparticles with controlled size are generated and well dispersed in the interconnected CNT framework. Controlled samples of Fe₂O₃@Fe₃O₄ and Fe₃O₄/CNT have also been prepared and used to investigate the synthetic mechanism and evaluate the lithium-ion storage performances. As an anodic active material for lithium-ion batteries, the Fe₂O₃@Fe₃O₄/CNT composite delivered a high reversible capacity of about 924 mAh·g^-1 for 200 continual charge/discharge cycles under a high current rate of 1000 mA·g^-1. As a catalyst in a Fenton-like reaction for degrading methyl orange (MO) contaminant in waterbody, the Fe₂O₃@Fe₃O₄/CNT composite exhibited an attractive decomposition efficiency (99.5% decomposition within 60 min) and good stability. The beneficial factors contributing to the inspiring performances are discussed. The effective and scalable material design and synthesis method can be regarded to have good potential in other fields.

"Carbon quantum dots-glue" enabled high-capacitance and highly stable nickel sulphide nanosheet electrode for supercapacitors

A facile "carbon quantum dots glue" strategy for the fabrication of honeycomb-like carbon quantum dots/nickel sulphide network arrays on Ni foam surface is successfully demonstrated. This design realizes the immobilization of nanosheet arrays and maintains a strong adhesion to the collector, forming a three-dimensional (3D) honeycomb-like architecture. Thanks to the unique structural advantages, the resulting bind-free electrode with high active mass loading of 6.16 mg cm^-2 still exhibits a superior specific capacitance of 1130F g^-1 at 2 A g^-1, and maintains 80% of the initial capacitance even at 10 A g^-1 after 3000 cycles. Furthermore, the assembled asymmetrical supercapacitor delivers an energy density of 18.8 Wh kg^-1 at a power density of 134 W kg^-1, and outstanding cycling stability (100% of initial capacitance retention after 5000 cycles at 5 mA cm^-2). These impressive results indicate a new perspective to design various binder-free electrodes for electrochemical energy storage devices.

High-performance supercapacitor based on highly active P-doped one-dimension/two-dimension hierarchical NiCo2O4/NiMoO4 for efficient energy storage

Multi-dimensional metal oxides have become a promising alternative electrode material for supercapacitors due to their inherent large surface area. Herein, P-doped NiCo₂O₄/NiMoO₄ multi-dimensional nanostructures are synthesized on carbon clothes (CC) with a continuous multistep strategy. Especially, P has the best synergistic effect with transition metals, such as optimal deprotonation energy and OH^- adsorption energy, which can further enhance electrochemical reaction activity. For the above reasons, the P-NiCo₂O₄/NiMoO₄@CC electrode exhibits an ultra-high specific capacitance of 2334.0 F g^-1 at 1 A g^-1. After 1500 cycles at a current density of 10 A g^-1, its specific capacity still maintains 93.7%. Besides, a P-NiCo₂O₄/NiMoO₄@CC//activated carbon device (hybrid supercapacitor or device) was also prepared with a maximum energy density of 45.1 Wh kg^-1 at a power density of 800 W kg^-1. In particular, the capacity retention rate is still 89.97% after 8000 cycles due to its excellent structural stability. Our work demonstrates the vast potential of multi-dimensional metal oxides in energy storage.