Supercapacitors have become a popular form of energy-storage device in the current energy and environmental landscape, and their performance is heavily reliant on the electrode materials used. Carbon-based electrodes are highly desirable due to their low cost and their abundance in various forms, as well as their ability to easily alter conductivity and surface area. Many studies have been conducted to enhance the performance of carbon-based supercapacitors by utilizing various carbon compounds, including pure carbon nanotubes and multistage carbon nanostructures as electrodes. These studies have examined the characteristics and potential applications of numerous pure carbon nanostructures and scrutinized the use of a wide variety of carbon nanomaterials, such as AC, CNTs, GR, CNCs, and others, to improve capacitance. Ultimately, this study provides a roadmap for producing high-quality supercapacitors using carbon-based electrodes.

Herein, we present an interfacial engineering strategy to construct an efficient hydrothermal approach by in situ growing cobalt-doped@MnO₂ nanocomposite on highly conductive nickel foam (Ni foam) for supercapacitors (SCs). The remarkably high specific surface area of Co dopant provides a larger contacting area for MnO₂. In the meantime, the excellent retentions of the hierarchical phase-based pore architecture of the cobalt-doped surface could beneficially condense the electron transportation pathways. In addition, the nickel foam (Ni foam) nanosheets provide charge-transport channels that lead to the outstanding improved electrochemical activities of cobalt-doped@MnO₂. The unique cobalt-doped@MnO₂ nanocomposite electrode facilitates stable electrochemical architecture, multi-active electrochemical sites, and rapid electro-transports channels; which act as a key factor in enhancing the specific capacitances, stability, and rate capacities. As a result, the cobalt-doped@MnO₂ nanocomposite electrode delivered superior electrochemical activities with a specific capacitance of 337.8 F g^–1 at 0.5 A g^–1; this is greater than pristine MnO₂ (277.9 F g^–1). The results demonstrate a worthy approach for the designing of high-performance SCs by the grouping of the nanostructured dopant material and metal oxides.

The need for energy storage and conversion is growing as a result of the worsening consequences of climate change and the depletion of fossil fuels.

All-solid-state batteries offer secure energy storage. Nanomaterials boost performance, but challenges include reducing electrolyte size while maintaining conductivity. This review highlights recent advances in electrode-electrolyte interfaces.

Long-term dynamic tracking of cells with theranostic properties remains challenging due to the difficulty in preparing and delivering drugs by probes. Herein, we developed highly fluorescent one- and two-photon (OP and TP) excitable polyphenolic carbon quantum dots (CQDs) for excellent membrane-targeting and drug delivery properties for synergistic tumor therapy. The green-emissive CQDs (g-CQDs) were synthesized from a three-fold symmetric polyphenolic molecule, phloroglucinol (C_3h; symmetry elements: E, C₃, C₃ ², σ_h, S₃, and S₃ ⁻¹), in a sulfuric acid medium. Doxorubicin (Dox) was loaded onto the g-CQDs via electrostatic interaction, resulting in a loading efficiency and content of 54.62% and 323.25 μg mL⁻¹, respectively. The g-CQDs@Dox complex exhibited a higher rate of cell killing efficiency at both pH 5.0 and 6.5, with higher reactive oxygen species (ROS) generation due to the greater Dox accumulation in the tumor cells. In addition, TP cell imaging displayed excellent membrane-targeting properties with less photobleaching ability in tumor cells. The in vivo studies confirmed that the g-CQDs@Dox complex has higher affinity towards tumor cells, better inhibitory effects, and an absence of systemic toxicity. Therefore, our developed nanocarrier exhibited better cell imaging, drug delivery, and tumor-targeting properties, and could be used as a “smart” probe for synergistic tumor therapy.

Battery-type electrode materials have attracted much attention as efficient and unique types of materials for hybrid battery supercapacitors due to their multiple redox states and excellent electrical conductivity. Designing composites with high chemical and electrochemical stabilities is beneficial for improving the energy storage capability of battery-type electrode materials. We report on an interfacial engineering strategy to improve the energy storage performance of a Co(OH)₂-based battery-type material by constructing polypyrrole-assisted and Ag-doped (Ag-doped@Co(OH)₂@polypyrrole) nanosheets (NSs) on a Ni foam using a hydrothermal process that provides richer electroactive sites, efficient charge transportation, and an excellent mechanical stability. Physical characterization results revealed that the subsequent decoration of Ag nanoparticles on Co(OH)₂ nanoparticles offered an efficient electrical conductivity as well as a reduced interface adsorption energy of OH^- in Co(OH)₂ nanoparticles as compared to Co(OH)₂@polypyrrole-assisted nanoparticles without Ag particles. The heterogeneous interface of the Ag-doped@Co(OH)₂@polypyrrole composite exhibited a high specific capacity of 291.2 mAh g⁻¹ at a current density of 2 A g⁻¹, and showed a good cycling stability after 5000 cycles at 5 A g⁻¹. The specific capacity of the doped electrode was enhanced approximately two-fold compared to that of the pure electrode. Thus, the fabricated Ag-doped@Co(OH)₂@polypyrrole nanostructured electrodes can be a potential candidate for fabricating low-cost and high-performance energy storage supercapacitor devices.