Inverted design of oxygen vacancies modulated NiCo2O4 and Co3O4 microspheres with superior specific surface area as competitive bifunctional materials for supercapacitor and hydrogen evolution reaction

Overview of the oxygen vacancy effect in bimetallic spinel and perovskite oxide electrode materials for high-performance supercapacitors

“…The intrinsic behavior and corresponding surface area of the microspheres in the above spinel materials were enhanced as the reduction progressed. 92 The modulated intrinsic behavior in NiCo 2 O 4 spinel can lead to the generation of OVs, and this was verified by the EPR technique. The EPR characterization displayed the highest paramagnetic transition signal intensity at g = 2.003 compared to their pristine NiCo 2 O 4 and Co 3 O 4 materials.…”

Constructing Flexible All‐Solid‐State Supercapacitors from 3D Nanosheets Active Bricks via 3D Manufacturing Technology: A Perspective Review

“…In the preparation of 3D nanosheet capacitive materials (e.g., graphene and MXene), template method is the most extensive preparation method, in which the most used templates are solid spherical templates (such as silica spheres and polymer spheres) and ice crystal templates. [68][69][70][71][72][73][74] The spherical template can be assembled into a unique honeycomb 3D nanosheet structure. The pore diameter of 3D nanosheets with the silica spheres template is small (≈50-100 nm), but the template stripping is relatively harsh (hydrofluoric acid is required).…”

“…The pore diameter of 3D nanosheets with the silica spheres template is small (≈50-100 nm), but the template stripping is relatively harsh (hydrofluoric acid is required). [68,69] The pore size of 3D nanosheets with polymer sphere template is large (≈100-500 nm), and the removal of the template is relatively simple (high temperature pyrolysis). [70][71][72] Spherical templates can be used for the preparation of 3D powder products [71] and thinfilm products, [72] which mainly depends on the forming process and product toughness and strength.…”

Ultrastable Asymmetric Supercapacitor Device with Chemically Derived and Mechanically Activated NiCo2O4

“…This ensures a fast redox reaction and improves the charge–discharge time and specific capacitance of the material. Among all binary metal oxides, NiCo 2 O 4 is a promising material because of its low cost, valence states, electrochemical performance, higher electrical conductivity (10 –1 to 10 s cm –1 ), and easily tunable morphology. − Scientists have already grown nickel cobaltite in different ways by orienting shape and size (1-D nanowire, 2-D nanosheets, nano-urchin, nanoflower, 3-D nanohierarchical structure) or coupling with other metal oxides to exploit their maximum potential in the energy field. − However, in most cases, advanced materials show low power and energy density, low cycle life, and low potential window. Scientists are searching for an exact strategy to grow nickel cobaltite with the best electrochemical performance.…”