In situ synthesis of nanostructured Fe3O4@TiO2 composite grown on activated carbon cloth as a binder-free electrode for high performance supercapacitors

Magnetic self-doped TiO2-x /Fe3O4@g-C solar-driven photocatalytic composite for water decontamination

Declining water resources and their contamination with chemicals risk the aquatic environment. Therefore, this work was devoted to designing a magnetically recyclable photocatalyst suitable for water treatment, namely, a TiO2-x /Fe3O4@g-C composite. Different preparation conditions were investigated together with the corresponding characteristics. The pure defective anatase TiO2-x phase of low band gap energy was detected through XRD and DRS analyses. Low charge recombination after the formation of defects was confirmed. The performances of the prepared photocatalysts in phenol degradation under solar light were evaluated, revealing the superior efficiency of TiO2-x prepared hydrothermally at 200 °C/24 h relative to intact TiO2. This best sample was incorporated with Fe3O4@g-C to facilitate its recovery and reuse. This successful combination was confirmed using XRD, Raman and XPS tools. TiO2-x /Fe3O4@g-C 2 : 1 formulation was found to be the most photoactive and could be reused up to five times without significant loss in its efficiency. Therefore, the precisely developed magnetic photocatalyst is promising for application in the water-treatment process.

Tailoring a facile electronic and ionic pathway to boost the storage performance of Fe3O4 nanowires as negative electrode for supercapacitor application

Today, high-energy applications are devoted to boosting the storage performance of asymmetric supercapacitors. Importantly, boosting the storage performance of the negative electrodes is a crucial topic. Fe3O4-based active materials display a promising theoretical storage performance as a negative electrode. Thus, to get a high storage performance of Fe3O4, it must be tailored to have a higher ionic and electronic conductivity and outstanding stability. Functionalized graphite felt (GF) is an excellent candidate for tailoring Fe3O4 with a facile ionic and electronic pathway. However, the steps of the functionalization of GF are complex and time-consuming as well as the energy loss during this step. Thus, the in-situ functionalization of the GF surface throughout the synthesis of Fe3O4 active materials is proposed herein. Fe3O4 is electrodeposited at the in-situ functionalized GF surface with the crystalline nanowires-like structure as revealed from the various analyses; SEM, TEM, Mapping EDX, XPS, XRD, wettability test, and Raman analysis. Advantageously, the synthetic approach introduces full homogeneous and uniform coverage of the large surface area of the GF. Thus, Fe3O4 nanowires with high ionic and electronic conductivity are characterized by a higher storage performance. Interestingly, Fe3O4/GF possesses a high specific capacity of 1418 mC cm-2 at a potential scan rate of 10 mV s-1 and this value retained to 54% at a potential scan rate of 50 mV s-1 at an extended potential window of 1.45 V. Remarkably, the diffusion-controlled reaction is the main contributor of the storage of Fe3O4/GF electrode as revealed by the mechanistic studies.

Environmentally Friendly Water-Based Reduced Graphene Oxide/Cellulose Nanofiber Ink for Supercapacitor Electrode Applications

The agglomeration of reduced graphene oxide (rGO) in water makes the development of rGO inks for supercapacitor printing challenging. Cellulose nanofiber (CNF), a biodegradable and renewable nanomaterial, can act as a nanospacer, preventing the agglomeration and restacking of rGO flakes. In this work, rGO/CNF films were fabricated using an environmentally friendly water-based rGO/CNF ink. In the absence of an additional binder/surfactant, the rGO/CNF films demonstrated remarkably enhanced hydrophilicity while retaining good electrical conductivity. The concentration of CNF was varied to observe the variation in the electrochemical performance. At a current density of 1 mA/cm2, the rGO/CNF-15 film exhibited a maximum areal capacitance of 98.61 mF/cm2, closely matching that of pure rGO films. Because of its excellent electrical performance, ease of manufacturing, and environmental friendliness, this water-based rGO/CNF ink may have promising applications in the printing of supercapacitor electrodes.

Enhanced photocatalytic degradation of crystal violet dye and high-performance electrochemical supercapacitor applications of hydrothermally synthesised magnetic bifunctional nanocomposite (Fe3O4/ZnO)

The present investigation employed a facile hydrothermal approach for the fabrication of Fe3O4/ZnO dual-functional magnetic nanocomposite. Supercapacitor and visible-light-driven photocatalytic applications of the material were explored. X-ray diffraction, Fourier transform infrared spectra, ultraviolet-visible diffuse reflectance spectra (UV-vis/DRS), field emission scanning electron microscopy (FE-SEM), energy dispersive x-ray spectroscopy, and vibrating sample magnetometer were used to analyse the nanocomposite's structural, morphological, optical, and magnetic properties. The FE-SEM analysis demonstrated that the surface morphology of Fe3O4, ZnO, and the Fe3O4/ZnO nanocomposite consisted of nanoparticles, nanoflakes, and nanoparticles adhered to the nanoflakes, respectively. The maximum specific capacitance of the electrode based on the Fe3O4/ZnO nanocomposite was measured to be 736.36 Fg-1at a scan rate of 5 mVs-1. The electrode also demonstrated remarkable cycling stability, retaining 86.5% of its capacitance even after 3000 cycles. The Fe3O4/ZnO nanocomposite was found to have an optical bandgap of 2.7 eV, an average particle size of 22.5 nm, and a saturation magnetization of 68.7 emu g-1. The photocatalysis experiment was conducted using the optimised settings, which included a pH of 7.0, a dye concentration of 30 mg l-1, a catalyst dose of 1 g l-1, and a contact time of 120 min. The Fe3O4/ZnO nanocomposite exhibited a notable degradation efficiency towards crystal violet dye upon exposure to visible light, achieving a degradation efficiency of 96.9%. This performance surpassed that of pure ZnO, which attained a degradation efficiency of 70.2%. The nanocomposite exhibited a rate constant of 2.80 × 10-2min-1, which was found to be notably higher than that of pure ZnO (0.8 × 10-2min-1), as determined through modelling (pseudo-first order linear fit). The radical scavenger experiments indicated that the superoxide radicals and hydroxyl radicals are the primary reactive species. The Fe3O4/ZnO photocatalyst can be effectively isolated using a bar magnet. Remarkably, the photocatalytic efficiency of the material remained almost entirely intact even after undergoing four cycles of recycling. In addition, this research opens up exciting new possibilities for use in fields like energy storage and pollution control.

Fabrication of TiN/CNTs on carbon cloth substrates via a CVD–ALD method as free-standing electrodes for zinc ion hybrid capacitors

A novel fabrication of TiN/CNTs@CC was presented and can be used as electrodes with good flexibility and conductivity in ZIHCs.