Carbon quantum dots-embedded reduced graphene oxide compact films for highly pressure-tolerant electrodes

D Lin and ZY Zhou and RH Shi and B Chen and ZL Huang and HB Tang and J Wang and XG Zhu and C Shao and FM Han, JOURNAL OF MATERIALS CHEMISTRY A, 12, 19885-19890 (2024).

DOI: 10.1039/d4ta03719g

High-pressure environments require that power supplies of electronic devices can withstand high pressure without a hard shell. While compact reduced graphene oxide (rGO) electrodes enhance pressure tolerance, they suffer from compromised capacitance and power output due to the decreased ion-accessible surface area and blocked or collapsed ion channels. To overcome this challenge, carbon quantum dots (CQDs) were uniformly embedded into rGO film to create a compact yet porous electrode. This was achieved via a hydrothermal reaction to form a rGO/CQDs hydrosol by bonding CQDs to rGO nanosheets, followed by a subsequent vacuum filtering. The "spacer" function of CQDs improves the ion-accessible surface area, ion migration, and compressive strength of the rGO/CQDs films. Molecular dynamics simulations further confirm that embedded CQDs enhance both Young's modulus and the diffusion coefficient of hydronium ions within the rGO/CQDs films. Thus, at an ultra-high pressure of 360 MPa, the prepared rGO/CQDs films retained an impressive 81.2% of their initial capacitance (219.7 F cm-3 at 0.8 mA cm-2). The rGO/CQDs-based supercapacitors retained a high volumetric power density of 59.4 W cm-3 at 180 MPa. These findings demonstrate the great potential of rGO/CQDs films for pressure-tolerant power supply devices. Uniform CQD-embedded rGO films were made through hydrothermal reaction and vacuum filtration. CQDs boost ion transport and compressive strength. Remarkably, the films retain 81.2% capacitance under ultrahigh pressure (360 MPa).

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