The magnetic response of hybrid capacitors (HCs) has become an essential topic in practical applications and fundamental research, but because of the complicated contact surface between the electrode and electrolyte, identifying the effect of the morphologies of electrodes on the magnetic response remains challenging. Here, we prepared needle‐, weed‐ and net‐like Co3O4 as electrodes to investigate the morphology‐dependent HCs properties under a magnetic field (MF). The results showed that the capacity of the needle‐ and weed‐like electrode changes in a range of 5.8 % to −23.2 % and 12.8 % to −5.1 % at a scan rate from 5 to 100 mV/s with a 4000Gs magnetic field, while that of net‐like electrode changes from 45.3 % to 41.3 %. The different magnetic response is attributed to the effect of the morphology on electrolyte convection under an external magnetic field. This work favours understanding the magnetic dependence of HCs properties and pushes the practical application of HCs in magnetic environments.
Preparation of graphene materials with different microstructures is of great significance for the specific applications in various areas. Here, a modified electrochemical exfoliation method with controlled electrode distance is proposed to prepare exfoliated graphene, graphene quantum dots, and graphene oxide (EGr, EGQD, and EGO). Compared with electrolysis at a fixed location, the modified electrode distance can effectively tune the insertion speed and direction, as well as the kinetic rates of exfoliation processes. In specific, at a short electrode distance of 3 cm, it produced high-quality EGr with the size above 5 μm and thickness below 5 layers; when the electrode distance increased to 30 cm, EGQD with the size below 5 nm was produced. Further, the distance between 3 and 30 cm facilitate to produce EGO with ca. 15% O content. In addition, it is found that the reaction temperature, optimized electrolyte, and controlled potential can further optimize the exfoliation processes, which can achieve a high exfoliation rate of ca. 2000, 140, and 1500 g h-1 for EGr, EGQD, and EGO preparation in an industrial-scale system, respectively. These modified graphene materials can be directly applied in various areas. For example, EGr can act as an effective component to increase one order of the dielectric property of PVDF; EGQD can effectively generate a PL spectrum at ca. 550 nm; EGO can facilely form a conductive and flexible film trough self-assembly.
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