Hollow N-doped carbon @ O-vacancies NiCo2O4 nanocages with a built-in electric field as high-performance cathodes for hybrid supercapacitor

Built-in electric field guides oxygen evolution electrocatalyst reconstruction

Creating a built-in electric field (BIEF) in catalysts represents an effective strategy to promote electron transfer and induce asymmetric charge distribution, thereby facilitating surface dynamic reconstruction under oxygen evolution reaction (OER) conditions. This review summarizes recent advancements in the field of OER electrocatalysts, with a focus on regulating the work function of components to tailor the BIEFs to guide surface reconstruction processes. It also discusses the importance of surface reconstruction in improving electrocatalytic performance and the influence of BIEFs on the reconstruction of catalysts. By analyzing various strategies for manipulating electric fields for guiding surface reconstruction of OER electrocatalysts, along with numerous representative examples, this review highlights how these techniques can enhance catalytic activity and stability. The findings underscore the potential of engineered BIEFs as a powerful tool in the design of next-generation electrocatalysts, paving the way for more efficient energy conversion technologies.

Recent Advances in Flexible Wearable Technology: From Textile Fibers to Devices

Smart textile fabrics have been widely investigated and used in flexible wearable electronics because of their unique structure, flexibility and breathability, which are highly desirable with integrated multifunctionality. Recent years have witnessed the rapid development of textile fiber-based flexible wearable devices. However, the pristine textile fibers still can't meet the high standards for practical flexible wearable devices, which calls for the development of some effective modification strategies. In this review, we summarize the recent advances in the flexible wearable devices based on the textile fibers, putting special emphasis on the design and modifications of textile fibers. In addition, the applications of textile fibers in various fields and the critical role of textile fibers are also systematically discussed, which include the supercapacitors, sensors, triboelectric nanogenerators, thermoelectrics, and other self-powered electronic devices. Finally, the main challenges that should be overcome and some effective solutions are also manifested, which will guide the future development of more effective textile fiber-based flexible wearable devices.

Recent Research of NiCo2O4/Carbon Composites for Supercapacitors

Supercapacitors have played an important role in electrochemical energy storage. Recently, researchers have found many effective methods to improve electrode materials with more robust performances through the increasing volume of scientific publications in this field. Though nickel cobaltite (NiCo2O4), as a promising electrode material, has substantially demonstrated potential properties for supercapacitors, its composites usually show much better performances than the pristine NiCo2O4. The combination of carbon-based materials and NiCo2O4 has been implemented recently due to the dual mechanisms for energy storage and the unique advantages of carbon materials. In this paper, we review the recent research on the hybrids of NiCo2O4 and carbon nanomaterials for supercapacitors. Typically, we focused on the reports related to the composites containing graphene (or reduced graphene oxide), carbon nanotubes, and amorphous carbon, as well as the major synthesis routes and electrochemical performances. Finally, the prospect for the future work is also discussed.

Graphene Quantum Dots Pinned on Nanosheets-Assembled NiCo-LDH Hollow Micro-Tunnels: Toward High-Performance Pouch-Type Supercapacitor via the Regulated Electron Localization

A combined delicate micro-/nano-architecture and corresponding surface modification at the nanometer level can co-tailor the physicochemical properties to realize an advanced supercapacitor electrode material. Herein, nanosheets-assembled nickel-cobalt-layered double hydroxide (NiCo-LDH) hollow micro-tunnels strongly coupled with higher-Fermi-level graphene quantum dots (GQDs) are reported. The unique hollow structure endows the electrolyte accessible to more electroactive sites, while 2D nanosheets have excellent surface chemistry, which favors rapid ion/electron transfer, synergistically resulting in more super-capacitive activities. The experimental and density functional theory calculations recognize that such a precise decoration generally tunes the charge density distribution at the near-surface due to the Fermi-level difference of two components, thus regulating the electron localization, while decorating with conductive GQDs co-improves the charge mobility, affording superior capacitive response and electrode integrity. The as-acquired GQDs@LDH-2 electrode yields excellent capacitance reaching ≈1628 F g^-1 at 1 A g^-1 and durable cycling longevity (86.2% capacitive retention after 8000 cycles). When coupled with reduced graphene oxide-based negative electrode, the hybrid device unveils an impressive energy/power density (46 Wh kg^-1 / 7440 W kg^-1 ); moreover, a flexible pouch-type supercapacitor can be constructed based on this hybrid system, which holds high mechanical properties and stable energy and power output at various situations, showcasing superb application prospects.

Fabrication of dual-functional electrodes using oxygen vacancy abundant NiCo2O4 nanosheets for advanced hybrid supercapacitors and Zn-ion batteries

V-ZnCo2O4/Ni composites with rich oxygen vacancies are designed through a hydrothermal method followed by post calcination and reduction. This strategy enhanced electrical conductivity, modulated electronic structure, and increased active sites.

Urchin-like NiCo2O4 hollow microspheres with oxygen vacancies synthesized by self-template for supercapacitor

The designed urchin-like NiCo2O4 material exhibits excellent supercapacitive performance due to the hollow porous structure and oxygen vacancies.