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Porous magnetite (Fe3O4) and hematite (α-Fe2O3) nanoparticles were prepared via the sol-gel auto-combustion method. The gels were prepared by reacting ferric nitrates (as oxidants) with starch (as fuel) at an elevated temperature of 200 °C. Different ratios (Φ) of ferric nitrates to starch were used for the synthesis (Φ = fuel/oxidant). The synthesized iron oxides were characterized by Fourier transform infrared (FT-IR) spectroscopy, Raman spectroscopy, X-ray diffraction (XRD) spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), Brunauer-Emmet-Teller (BET) and vibrating sample magnetometer (VSM) analysis techniques. The crystal structure, morphology, and specific surface area of the iron oxide nanoparticles (Fe3O4 and α-Fe2O3) were found to be dependent on the starch content. The FT-IR, XRD and VSM analysis of the iron oxides for Φ = 0.3 and 0.7 confirmed the formation of the α-Fe2O3 core, whereas at Φ = 1, 1.7, and 2 showed that Fe3O4 cores were formed with the highest saturation magnetization of 60.36 emu/g at Φ = 1. The morphology of the Fe3O4 nanoparticles exhibited a quasi-spherical shape, while α-Fe2O3 nanoparticles appeared polygonal and formed clusters. The highest specific surface area was found to be 48 m² g-1 for Φ = 1.7 owing to the rapid thermal decomposition process. Type II and type III isotherms indicated mesoporous structures. [ABSTRACT FROM AUTHOR]

[Display omitted] • MoS 2 nanosheets were successfully deposited onto silicon nanowires (SiNWs) through hydrothermal process. • The MoS 2 /SiNWs heterostructure have been successfully prepared by combing hydrothermal and metal assisted chemical etching processes. • MoS 2 /SiNWs heterostructure exhibited an improvement of photocatalytic degradation of MB under visible light irradiation. Molybdenum disulfide (MoS 2) is weakly stacked by vander Waals force, and the interaction force between the layers of MoS 2 and Silicon is weak. Therefore, direct growth of homogeneous high quality MoS 2 films on silicon substrates stays challenging. Herein, for the first time, few layered MoS 2 nanosheetswere successfully deposited onto silicon nanowires (SiNWs) through hydrothermal process. First, as prepared MoS 2 /SiNWs heterostructure was characterized by using Raman spectroscopy, Scanning Electron Microscopy (SEM) and by means of the Energy-Dispersive X-ray spectroscopy (EDX). Second, the photocatalytic activity ofsynthesizedMoS 2 /SiNWs photocatalyst was systematically evaluated for the decoloration of methylene blue (MB) under visible light irradiation. It was found that MoS 2 /SiNWs heterostructure exhibited excellent photocatalytic activity against this dye compared with synthesized SiNWs films. Also, it was found that after irradiation during 180 min, the MoS 2 /SiNWs film exhibited the highest photocatalytic efficiency (90%), in comparison to SiNWs (62%). Finally, it is assumed that the photocatalytic activity improvement was attributed to visible light absorption improvement, the enhancement of the photogenerated electron-hole pair's separation efficiency. Moreover, thanks to the nanoflowers structure assembled by nanosheets with few layers, the specific surface area was increased offering more sites for MB pollutant adsorption. [ABSTRACT FROM AUTHOR]

Titanium dioxide nanorods arrays (NRAs) photoanodes have been grown by the hydrothermal method on FTO coated glass substrates for different hydrothermal reaction time. Synthesized TiO 2 NRAs films were compared in terms of their structural, optical and morphological properties. Their wettability and photoelectrochemical performances were also investigated. We found that the sample elaborated at 10 h has the best physical properties. SEM images show that the surface of the FTO substrate is uniformly covered by TiO 2 NRs with the optimum packing density. UV–vis-absorption measurements revealed that this sample exhibits good (excellent) light harvesting capabilities. The wettability tests revealed that this sample is more hydrophilic among all prepared samples. A strong correlation between morphological, optical and photoelectrochemical performance has been discussed. [ABSTRACT FROM AUTHOR]