The present work reports the formation of 3D nanoflower-like morphology of iron alkoxide via the anodization of Fe sheet in ethylene glycol (EG) electrolyte. XRD, FESEM, EDX, XPS, Raman and FTIR are applied to characterize the samples. SEM results show that the as-anodized sample is composed of 3D nanoflowers with hierarchical nanosheets beneath it. The average width of the nanoflower petal is ∼25 nm and the length is about 1 μm. The 3D nanoflowers are transformed into spherical nanoparticles (NPs) with uniform size when calcined at elevated temperature. XRD and Raman results indicate that the 3D nanoflowers consist of akaganeite, which transforms into magnetite and hematite by annealing. XPS and FTIR results confirm that the nanoflowers contain significant amounts of F, C and OH, which are drastically decreased after annealing. The formation of 3D nanoflower-like morphology can be attributed to EG. A possible formation mechanism of 3D nanoflowers and their transformation into NPs is proposed. We showed that the morphology of the as-anodized iron oxide can be tailored simply by changing the electrolyte. The anodization of Fe sheet in glycerol-based electrolyte under identical conditions produced nanotubes.

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A green, efficient, simple, and general route has been developed to synthesize a wide variety of metal oxide nanoparticles (NPs) in large quantities at room temperature. Various metal and alloy oxide NPs like In 2 O 3 , SnO 2 , ZnO, Fe 2 O 3 , NiO, TiO 2 , ZrO 2 , CuO, Al 2 O 3 , and sus-304L are synthesized by anodization of metals and alloy in KCl aqueous electrolyte. Metallic wire or sheet is very rapidly and directly converted into metal oxide NPs by the anodization process, allowing mass production of oxide NPs. The produced NPs are crystalline, and their colloidal suspensions in ethanol or water remain stable for several days. The size of the synthesized NPs can be readily tuned by changing the anodizing voltage. We found that the ultrafast reaction rate caused by chloride ions plays an important role in the formation of metal oxide NPs. The produced oxide NPs are characterized using various tools. SEM and TEM results confirm the formation of various metal oxide NPs. Sus oxide NPs shows higher catalytic efficiency compared to that of commercial magnetite NPs. Our results indicate that anodization is an efficient route for the production of good quality and diverse metal as well as alloy oxide NPs on a large scale. The possible formation mechanism is presented. This approach can also be applied to other complex metals and alloy oxide NPs.

We have presented a mechanism to explain why the resulting oxide morphology becomes a porous or a tubular nanostructure when a zircaloy is electrochemically anodized. A porous zirconium oxide nanostructure is always formed at an initial anodization stage, but the degree of interpore dissolution determines whether the final morphology is nanoporous or nanotubular. The interpore dissolution rate can be tuned by changing the anodization parameters such as anodization time and water content in an electrolyte. Consequently, porous or tubular oxide nanostructures can be selectively fabricated on a zircaloy surface by controlling the parameters. Based on this mechanism, zirconium oxide layers with completely nanoporous, completely nanotubular, and intermediate morphologies between a nanoporous and a nanotubular structure were controllably fabricated.

Cheap and visible-light responsive Cu/TiO2 photocatalysts were fabricated by illuminating ultraviolet (UV) to a mixture of TiO2 nanoparticles (NPs) and Cu2O NPs in an evacuated reaction chamber. The Cu2O NPs were reduced by UV in an oxygen-free reaction chamber, and hence, metallic Cu NPs with size less than 5 nm were uniformly loaded on TiO2. Due to the plasmon resonance of the Cu NPs, the Cu/TiO2 exhibited a good performance of water-splitting hydrogen production under visible light in the presence of glycerol as a hole scavenger. The optimum hydrogen production rate of Cu/TiO2 was 0.24 mmol h(-1) g(-1). The Cu/TiO2 also showed high stability of the photocatalytic performance in the evacuated chamber; however, the visible-light responsive photocatalytic properties dramatically and rapidly decreased when exposed to air.