A Nano-Rattle SnO2@carbon Composite Anode Material for High-Energy Li-ion Batteries by Melt Diffusion Impregnation

Tin Oxide (SnO2)-Decorated Reduced Graphene Oxide (rGO)-Based Hydroelectric Cells to Generate Large Current

Nonphotocatalytic water splitting through oxygen-deficient, mesoporous metal oxide design-based hydroelectric cells (HECs) is a well-known phenomenon. To exploit more power from HECs, a metal oxide with more oxygen deficiency is desirable. In this study, oxygen-deficient mesoporous SnO2 via a sol-gel method and its composites with reduced graphene oxide (rGO) have been presented. Raman spectra of SnO2-rGO nanocomposites revealed an increase in the oxygen vacancies, while the X-ray diffraction (XRD) pattern confirmed the strain formation in the nanocomposite lattice owing to defect formation. The X-ray photoemission spectroscopy (XPS) results also indicated the presence of oxygen vacancies on the surface of SnO2, whereas Brunauer-Emmett-Teller (BET) measurements revealed that adding rGO into SnO2 increased the surface area from 44.54 to 84.00 m2 g-1. The water molecules are chemidissociated on the oxygen-deficient mesoporous surface of the pellet followed by physiodissociation at the mesopores. The redox reaction of the dissociated ions at the Zn anode and the Ag inert cathode produces current in the outer circuit. Interestingly, adding few drops of water into a SnO2-rGO-based HEC resulted in a short-circuit current of 148 mA with an open-cell voltage of 1.0 V. The maximum power delivered by the SnO2-rGO-based HEC is 148 mW. The addition of rGO into SnO2 boosts the peak current remarkably from 68 to 148 mA, which is the highest reported current generated by a hydroelectric cell.

Green Biosynthesis of Tin Oxide Nanomaterials Mediated by Agro-Waste Cotton Boll Peel Extracts for the Remediation of Environmental Pollutant Dyes

The sustainable synthesis of metal oxide materials provides an ecofriendly and more exciting approach in the domain of a clean environment. Besides, plant extracts to synthesize nanoparticles have been considered one of the more superior ecofriendly methods. This paper describes the biosynthetic preparation route of three different sizes of tetragonal structure SnO₂ nanoparticles (SNPs) from the agro-waste cotton boll peel aqueous extract at 200, 500, and 800 °C for 3 h and represents a low-cost and alternative preparation method. The samples were characterized by X-ray diffraction, Fourier transform infrared spectrophotometry, ultraviolet-visible absorption spectroscopy, high-resolution transmission electron microscopy (HR-TEM), and energy-dispersive X-ray spectroscopy. Surface area and porosity size distribution were identified by nitrogen adsorption-desorption isotherms and Brunauer-Emmett-Teller analysis. The photocatalytic properties of the SNP samples were studied against methylene blue (MB) and methyl orange (MO), and the degradation was evaluated with three different size nanomaterials of 3.97, 8.48, and 13.43 nm. Photocatalytic activities were carried out under a multilamp (125 W Hg lamps) photoreactor. The smallest size sample exhibited the highest MB degradation efficiency within 30 min than the most significant size sample, which lasted 80 min. Similarly, in the case of MO, the smallest sample showed a more superior degradation efficiency with a shorter period (40 min) than the large-size samples (100 min). Therefore, our studies suggested that the developed SNP nanomaterials could be potential, promising photocatalysts against the degradation of industrial effluents.

Preparations of NiFe2O4 Yolk-Shell@C Nanospheres and Their Performances as Anode Materials for Lithium-Ion Batteries

At present, lithium-ion batteries (LIBs) have received widespread attention as substantial energy storage devices; thus, their electrochemical performances must be continuously researched and improved. In this paper, we demonstrate a simple self-template solvothermal method combined with annealing for the synthesis of NiFe2O4 yolk-shell (NFO-YS) and NiFe2O4 solid (NFO-S) nanospheres by controlling the heating rate and coating them with a carbon layer on the surface via high-temperature carbonization of resorcinol and formaldehyde resin. Among them, NFO-YS@C has an obvious yolk-shell structure, with a core-shell spacing of about 60 nm, and the thicknesses of the NiFe2O4 shell and carbon shell are approximately 15 and 30 nm, respectively. The yolk-shell structure can alleviate volume changes and shorten the ion/electron diffusion path, while the carbon shell can improve conductivity. Therefore, NFO-YS@C nanospheres as the anode materials of LIBs show a high initial capacity of 1087.1 mA h g-1 at 100 mA g-1, and the capacity of NFO-YS@C nanospheres impressively remains at 1023.5 mA h g-1 after 200 cycles at 200 mA g-1. The electrochemical performance of NFO-YS@C is significantly beyond NFO-S@C, which proves that the carbon coating and yolk-shell structure have good stability and excellent electron transport ability.