Interface Mo-N coordination bonding MoSxNy@Polyaniline for stable structured supercapacitor electrode

Endogenous Interfacial Mo-C/N-Mo-S Bonding Regulates the Active Mo Sites for Maximized Li+ Storage Areal Capacity

Active sites, mass loading, and Li-ion diffusion coefficient are the benchmarks for boosting the areal capacity and storage capability of electrode materials for lithium-ion batteries. However, simultaneously modulating these criteria to achieve high areal capacity in LIBs remains challenging. Herein, MoS2 is considered as a suitable electroactive host material for reversible Li-ion storage and establish an endogenous multi-heterojunction strategy with interfacial Mo-C/N-Mo-S coordination bonding that enables the concurrent regulation of these benchmarks. This strategy involves architecting 3D integrated conductive nanostructured frameworks composed of Mo2C-MoN@MoS2 on carbon cloth (denoted as C/MMMS) and refining the sluggish kinetics in the MoS2-based anodes. Benefiting from the rich hetero-interface active sites, optimized Li adsorption energy, and low diffusion barrier, C/MMMS reaches a mass loading of 12.11 mg cm-2 and showcases high areal capacity and remarkable rate capability of 9.6 mAh cm-2@0.4 mA cm-2 and 2.7 mAh cm-2@6.0 mA cm-2, respectively, alongside excellent stability after 500 electrochemical cycles. Moreover, this work not only affirms the outstanding performance of the optimized C/MMMS as an anode material for supercapacitors, underscoring its bifunctionality but also offers valuable insight into developing endogenous transition metal compound electrodes with high mass loading for the next-generation high areal capacity energy storage devices.

Recent Progress in Polyaniline and its Composites for Supercapacitors

Polyaniline (PANI) has piqued the interest of nanotechnology researchers due to its potential as an electrode material for supercapacitors. Despite its ease of synthesis and ability to be doped with a wide range of materials, PANI's poor mechanical properties have limited its use in practical applications. To address this issue, researchers investigated using PANI composites with materials with highly specific surface areas, active sites, porous architectures, and high conductivity. The resulting composite materials have improved energy storage performance, making them promising electrode materials for supercapacitors. Here, we provide an overview of recent developments in PANI-based supercapacitors, focusing on using electrochemically active carbon and redox-active materials as composites. We discuss challenges and opportunities of synthesizing PANI-based composites for supercapacitor applications. Furthermore, we provide theoretical insights into the electrical properties of PANI composites and their potential as active electrode materials. The need for this review stems from the growing interest in PANI-based composites to improve supercapacitor performance. By examining recent progress in this field, we provide a comprehensive overview of the current state-of-the-art and potential of PANI-based composites for supercapacitor applications. This review adds value by highlighting challenges and opportunities associated with synthesizing and utilizing PANI-based composites, thereby guiding future research directions.

Bimetallic CoSe2/FeSe2 hollow nanocuboids assembled by nanoparticles as a positive electrode material for a high-performance hybrid supercapacitor

Design and fabrication of impressive and novel electrode materials for energy storage devices, especially supercapacitors, are of great importance. Herein, bimetallic CoSe₂/FeSe₂ hollow nanocuboid nanostructures derived from Co/Fe-Prussian Blue analogues (denoted as CoSe₂/FeSe₂ HNCs) are successfully designed and fabricated as a remarkable positive electrode material for high-performance supercapacitors. The bimetallic CoSe₂/FeSe₂ HNC nanostructures can have increased active sites and short electron-ion diffusion pathways. Bimetallic CoSe₂/FeSe₂ HNCs@NiF as a positive electrode showed efficient supercapacitive properties with a great specific capacity of 332.75 mA h g^-1 (1197.90 C g^-1) at 1 A g^-1, retaining 80.61% of its initial capacity at 20 A g^-1, considerable longevity (91.47% of its initial capacity after 10 000 cycles) and an excellent coulombic efficiency of 98.49%. Also, the designed and fabricated CoSe₂/FeSe₂ HNCs@NiF||AC@NiF hybrid supercapacitor device using bimetallic CoSe₂/FeSe₂ HNCs@NiF (positive electrode) and activated carbon@NiF (AC, negative electrode) exhibited an efficient energy density of 63.62 W h kg^-1 and a superior durability of 91.14% after 10 000 cycles.

Fabrication of Highly Ordered Ag/TiO2 Nanopore Array as a Self-Cleaning and Recycling SERS Substrate

Silver nanoparticles deposited on a titania nanopore array (Ag/TiO2 NPA) has been designed as a surface-enhanced Raman scattering (SERS) substrate for sensitive and recycling application of organic molecule detection. A TiO2 NPA was fabricated by a surface oxidization reaction of a titanium sheet by a double anodization process. A Ag/TiO2 NPA was then formed by depositing silver nanoparticles onto the TiO2 NPA by a cycling chemical reduction deposition process. The Ag/TiO2 NPA has a uniform mono-layer dispersion of Ag nanoparticles with a size of 30–50 nm on TiO2 nanopores with a diameter of 100–110 nm. The Ag/TiO2 NPA SERS substrate could facilitate interfacial adsorption of Rhodamine 6G (R6G), which achieves a sensitive detection limit of 10−8 M R6G through SERS spectrum measurement. The Ag/TiO2 NPA SERS substrate achieves an analytical enhancement factor value of 2.6 × 105. The Ag/TiO2 NRA could promote the UV light-excited photocatalytic degradation reaction of R6G adsorbed on its surface which gives rise to a refreshed Ag/TiO2 NRA under UV irradiation for 60 min and accordingly behave as a self-cleaning and recycling SERS substrate. The Ag/TiO2 NPA exhibits a much higher R6G degradation reaction rate constant (0.05764 min−1) than the TiO2 NPA (0.02600 min−1), indicating its superior photocatalytic activity and self-cleaning activity. The refreshed Ag/TiO2 NPA was able to be recycled for the Raman detection of R6G, maintaining a high stability, reproducibility, and cyclability. The highly ordered Ag/TiO2 NPA with well controlled Ag nanoparticle dispersion and TiO2 nanopore shape could act as a suitable SERS substrate for recycling and self-cleaning application for stable and sensitive molecule detection.