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In the biomedical field, because invasive surgery requires large incisions, which can cause adverse reactions such as bleeding, pain, and tissue scarring, people tend to prefer non-invasive medical methods. With the increasing popularity of non-invasive biomedical devices, there is an urgent need to develop small, easy-to-commercialize, and bio-friendly effective energy storage devices.
Recently, the team of Professor Jae Su Yu of Kyung Hee University in South Korea published a research result entitled "Micro-supercapacitors based on fungi derived biocarbon microfibers infused with NiMoO nanoparticles for biomedical and E-skin applications" in Advanced Fiber Materials, systematically describing the preparation and application of bio-friendly micro supercapacitors (BMSCs). Through the characterization of material properties and electrochemical properties and the actual application effect, it is proved that this biocarbon material has broad application prospects in the biomedical field and the field of electronic skin technology.
The main point of this paper
Figure 1 shows the synthesis process of NiMoO NPs@BCMFs material, including extracting fibers from Laetiporus sulphureus fungi, and then drying, crushing, chemical treatment and high temperature annealing to finally obtain biocarbon microfibers doped with NiMoO nanoparticles.
From the FE-SEM image of Figure 2 (a), it can be seen that NiMoO NPs@BCMFs are composed of many microfibers and microcapillary structures; the EDX surface analysis results of Figure 2 (b-c) confirm that Ni, Mo, C, N and O elements exist in the structure; the TEM image of Figure 2 (d) shows the internal structure and distribution of NiMoO NPs@BCMF nanoparticles; the lattice fringe pattern and selected area electron diffraction (SAED) analysis of Figure 2 (e-f) confirm that NiMoO NPs are polycrystalline.
The XRD spectrum of NiMoO NPs@BCMF is shown in Figure 3 (a); the full spectrum scan of XPS is shown in Figure 3 (b), showing the peaks of Ni 2p, Mo 3d, O 1s, C 1s and N 1s, which is consistent with the EDX analysis results. Figures 3 (c-g) are the core energy level spectra of Ni 2p, Mo 3d, O 1s, C 1s and N 1s, respectively. The fitting analysis reveals the +2 and +3 oxidation states of Ni, the +6 oxidation state of Mo, the three chemical states of oxygen atoms, the single and double bonds of carbon atoms, and the doping forms of nitrogen atoms. Among them, the N 1s spectrum shows the presence of pyridinic nitrogen, pyrrolic nitrogen and graphitic nitrogen. Figure 3 (h) is a Raman spectrum, showing the D band related to the disorder of carbon atoms and the G band related to sp2 hybridized carbon atoms, and ID/IG is used to represent the degree of disorder of carbon in the sample.
Figure 4 (a-b) shows the excellent electrochemical reaction activity and large area capacity of NiMoO NPs@BCMFs; the area capacity value calculated based on the constant current charge-discharge curve (GCD) in Figure 4 (c) further confirms the excellent electrode performance of NiMoO NPs@BCMFs/NF; Figure 4 (d-e) respectively show the cyclic voltammetry curve (CV) and GCD of NiMoO NPs@BCMFs/NF electrode at different scan rates and current densities, showing the stability and reversibility under different conditions; Figure 4 (f-g) respectively show the excellent performance of the electrode material at different current densities and excellent cycle stability; Figure 4 (h) is the electrochemical impedance spectroscopy (EIS) diagram of NiMoO NPs@BCMFs/NF electrode before and after cycling, and the charge transfer characteristics of the electrode are analyzed by fitting the equivalent circuit; Figure 4 (i) is a functional schematic diagram of NiMoO NPs@BCMFs electrode.
Figure 5 shows the application potential of BCMFs as negative electrode materials in supercapacitors. The cleaned, crushed and dehydrated fungi were immersed in a 2 mol/L KOH solution, and then BCMFs were obtained by centrifugation and drying (Figure 5a). The annealed BCMFs have an internal microporous structure (Figure 5b), and micropores and nanopores can be observed by FE-SEM (Figure 5c); Raman spectrum analysis in Figure 5 (d) shows D band and G band, indicating the disordered vibration of carbon atoms and the ordered vibration of SP2 hybridized carbon atoms; BCMFs were subjected to non-Faraday charge and discharge, and Figure 5 (e-g) shows the application potential of BCMFs as negative electrode materials in supercapacitors.
Figure 6 shows the design and performance test results of BMSC, where: (a) is a schematic diagram of the structural composition, including positive and negative electrodes, electrolytes, and packaging materials; (b) is the cyclic voltammetry curve of the NiMoO NPs@BCMFs/NF and BCMFs/NF electrode combinations; (c-f) are the electrochemical performance of the device under different conditions; (g) shows the area capacitance value of BMSC calculated based on the GCD curve; (h) shows the maximum energy density and maximum power density of the device; (i-j) respectively show the performance stability of the BMSC device in long-term cycle tests and under rapidly changing current density.
Figure 7 shows the practical test results of the BMSC device, where: (c) is the electrochemical performance in a bent state, (d-e) are the voltage and current output capabilities under series-parallel conditions, (f) is the self-discharge rate under open circuit conditions, and (g-k) are applications in E-bracelet electronic bracelets, electronic muscle stimulators (EMS), oscilloscopes, direct current motors (DCMs), and LED light power supplies. The above research results confirm that BMSC devices have the potential for application in power sources for wearable electronic devices and biomedical devices.
In summary, this work uses a simple two-step process to prepare a biomaterial-based micro-supercapacitor NiMoO NPs@BCMFs/NF. The electrode has excellent area capacity and cycling stability. In addition, a flexible, bio-friendly BMSC device was fabricated using NiMoO NPs@BCMFs/NF and BCMF/NF electrodes and tested in biomedical applications to power EMS in three different modes. BMSC can also power wearable electronic skin technology and other electronic devices.
Electrospinning Nanofibers Article Source:
https://link.springer.com/article/10.1007/s42765-024-00384-x
