In this paper, porous zinc oxide (ZnO) nanosheets were successfully prepared by a simple low-temperature hydrothermal method. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and Brunauer–Emmett–Teller (BET) tests showed that the synthesized product was ZnO with porous sheet structure. The diameter of porous nanosheets was about 100 nm and the thickness was about 8 nm. As a photocatalyst, the degradation efficiencies of porous ZnO nanosheets for methyl orange (MO), methylene blue (MB) and Rhodamine B (RhB) were 97.5%, 99% and 96.8%, respectively. In addition, the degradation efficiency of ZnO for mixed dyes (Mo, MB and RhB) was satisfactory, reaching 97.7%. The photocatalytic stability of MB was further tested and remained at 99% after 20 cycles. In the experiment, ZnO/FTO (fluorine-doped tin oxide) composites were prepared by using ZnO as the conductive layer. Titanium dioxide (TiO₂) was deposited on the surface of ZnO/FTO by electrodeposition, so as to obtain a TiO₂/ZnO/FTO composite. By studying the electrochromic properties of this composite, it was found that the TiO₂/ZnO/FTO composite shows a large light modulation range (55% at 1000 nm) and excellent cycle stability (96.6% at 200 cycles). The main reason for the excellent electrochromic properties may be the synergistic effect between the porous structure and the polymetallic oxides. This study is helpful to improve the photocatalytic efficiency and cycling stability of metal oxides, improve the transmittance of thin films and provide a new strategy for the preparation of ZnO composite materials with excellent photocatalytic and electrochromic properties.

Microbial fuel cells (MFCs) have exhibited potential in energy recovery from waste. In this study, an MFC reactor with a polyaniline–sodium alginate–graphene oxide (PANI–SA–GO)/carbon brush (CB) hydrogel anode achieved maximum power density with 4970 mW/m³ and produced a corresponding current density of 4.66 A/m², which was 2.72 times larger than the MFC equipped with a carbon felt film (CF) anode (1825 mW/m³). Scanning electron microscopy indicated that the PANI-SA-GO/CB composite anode had a three-dimensional macroporous structure. This structure had a large specific surface area, providing more sites for microbial growth and attachment. When the charging-discharging time was set from 60 min to 90 min, the stored charge of the PANI-SA-GO/CB hydrogel anode (6378.41 C/m²) was 15.08 times higher than that of the CF (423.05 C/m²). Thus, the mismatch between power supply and electricity consumption was addressed. This study provided a simple and environment-friendly modification method and allowed the prepared PANI–SA–GO/CB hydrogel anode to markedly promote the energy storage and output performance of the MFC.

Microbial fuel cell (MFC) technology can potentially recover bioelectricity from wastewater. However, its practical applications have been limited because of its low power density and since the energy generated from an MFC cannot be stored. In this study, manganese dioxide (MnO₂) coupled with carbon nanotubes (CNT) was chosen to in situ modify carbon felt (CF) as a capacitive bioanode (CF/CNT/MnO₂) to improve the power generation and energy storage of MFCs. The maximum power density of the MFC with the MnO₂-CNT-modified bioanode reached 3471.6 mW m³, which was 1.96 times higher than that of the CF/CNT anode (1772.6 mW m⁻³). During the experiment of charging for 30 min and discharging for 30 min, the MFC with a capacitive bioanode had a total charge of 8777.1 C m⁻², 2.74 times higher than that of the CF/CNT anode. The excellent electricity-producing and energy storage performance of the MFC equipped with the CF/CNT/MnO₂ anode is attributed to the composite materials, which can be due to their better biocompatibility, large capacitance, and high specific surface area. This study provides a new way to improve the performance of electricity generation and energy storage of MFCs.

Microbial fuel cells (MFCs) are electrochemical electricity generation devices that use microorganisms to degrade organic matter to produce electrical energy. The anode of microbial fuel cells (MFCs) is the carrier to which electrogenic microorganisms attach. However, traditional anodes do not have a storage function, which limits the application scope of microbial fuel cells. Effectively storing and utilizing the energy generated by MFCs is an important focus of ongoing research and is also key to realizing their effective application. A carbon felt film (CF) was used as the substrate, and a carbon felt film/ferrosoferric oxide (CF/Fe₃O₄) electrode was prepared by a hydrothermal method. In the power density test, the MFC system constructed with the CF/Fe₃O₄ electrode as a capacitive biological anode had a maximum power density of 5.09 W/m³, which was 4.43 times higher than that of the blank carbon felt film anode. In the charge–discharge test, the stored charge (Q_s) released by the CF/Fe₃O₄ electrode was 157.12 C/m² higher than that of the CF electrode after 45 min of charging–discharging. The modified ferrosoferric oxide anode was used in a microbial fuel cell to provide a scientific basis to construct microbial electrochemical systems with high power and energy storage functions.

Microbial fuel cells (MFCs) have shown promise in solving energy and environmental problems, but their practical application is limited by their low power output. In this study, carbon nanotubes/polypyrrole composite anode materials were prepared on a porous sponge matrix. By combining the porous characteristics of sponge, the good conductive properties of carbon nanotubes, and the energy storage ability of polypyrrole capacitive materials, the prepared anode exhibited a large specific capacity, high porosity, large specific surface area, good electron transport ability, and good biocompatibility. The results showed that the maximum power density of the modified anode MFC reached 7.46 W m⁻³, which was 2.53 times higher than that of the control anode. The stored energy Q_s released by the modified anode was 235.6 C m⁻², 6.5 times higher than that of the control electrode. In addition, the transfer impedance R_ct of the S/CNT/PPy electrode (5.5 Ω) was much lower than that of the control anode (16.8 Ω). The research presented in this paper demonstrates a new approach to improving the power generation ability and energy storage performance of MFCs.