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In this article, we report the fabrication of gallium oxide (α-Ga2O3) microspheres (GOMs) by a self-assembly process. Gallium nitrate with oxalic acid in a hydrothermal process results in α-GaOOH, which was further converted into gallium oxide by calcinations at 450 °C for 3 h. We first report the formation of various morphological α-GaOOH by using the above-mentioned methodology. The influence of hydrothermal temperature and time on the crystal structure and its morphology was studied, and the results indicated that hydrothermal temperature played an important role in the final morphology of α-GaOOH. The flower-like α-GaOOH formed at 175 °C is converted into rodlike α-Ga2O3 after calcination at 450 °C, and the α-GaOOH microsphere and microrod formed at 200 and 225 °C retained their morphology during the calcination process, respectively. The synthesized α-GaOOH and α-Ga2O3 were characterized using X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), high-resolution transmission electron microscopy (HR-TEM), and nitrogen adsorption analysis. The XRD patterns indicated that well-crystallized α-GaOOH and α-Ga2O3 were formed in a hydrothermal and calcination process, respectively. The FE-SEM images indicated the formation of well-organized microspheres and microflowers, which were composed of nanoparticles and nanoplates, respectively. The photocatalytic degradation of Acid Orange 7 (AO7) dye and Cr(VI) reduction by using the synthesized GOM under UV light irradiation was investigated. The photocatalytic experiment showed superior photocatalytic activity of GOM having a higher efficiency than TiO2. We propose a plausible mechanism for the formation of various morphologies of α-GaOOH and α-Ga2O3.

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A new N, C codoped visible light responsive hierarchical porous ZnS photocatalysts have been successfully synthesized by using a simple procedure in large scale without using catalyst or template. This is a first example of a nonmetal doped sulfide semiconductor photocatalyst working under visible light irradiation. N, C codoped ZnS catalysts were formed by thermal decomposition of zinc isothiocyanate at 300, 400, and 500 °C under open atmospheric conditions. The influences of various experimental conditions on the morphology of the catalysts have been investigated. The synthesized catalysts were characterized by the required analytical techniques. The N, C codoped catalysts possess well-crystallized wurtzite structure and have excellent visible light absorption when compared to undoped ZnS. Elemental and XPS analyses confirmed the presence of both nitrogen and carbon elements in ZnS. The chemical natures of nitrogen and carbon have been discussed on the basis of FTIR and XPS results. The visible light induced photocatalytic activity of these catalysts were investigated by using AO7 as a model pollutant and results showed that the synthesized catalysts have excellent photocatalytic activity. A possible growth mechanism of the hierarchical porous photocatalysts was proposed.