Bi2WO6 powders were synthesized by the molten salt method at 250-350 ºC using the mixture of Bi(NO3)3·5H2O and Na2WO4·2H2O as a precursor, and the mixture of LiNO3 and NaNO3 with a molar ratio of 27:33 as a molten salt, respectively. The effects of temperature and salt amount on the phase composition, morphology and photocatalytic activity under the visible light irradiation were investigated. The results revealed that pure phase Bi2WO6 powders could be synthesized at 350 ºC as the weight of molten salts were 2‒5 times as many as the precursor. Bi2WO6 powder synthesized with lower salt amount exhibited larger surface area, more abundant pores, narrower bandgap and lower PL intensity, all of which contributed a higher photocatalytic activity. The synthesized Bi2WO6 powder could degrade 0.01 mol/L Rhodamine-B solution by 97% after irradiation under visible light for 60 min. The obtained Bi2WO6 powder had a good photochemical stability and reusability, revealing potential application in environmental treatment.

A novel adsorbent based nanostructured bismuth oxyiodide (BiOI) microspheres combining the highly effective adsorption and green photocatalytic regeneration were fabricated by a facile and rapid low-temperature chemical bath method. The resultant products were characterized by X-ray diffraction (XRD), Scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), Nitrogen adsorption-desorption measurements, and UV-Vis diffuse reflectance spectroscopy (DRS). The BiOI microspheres displayed remarkable performance towards removal of Rhodamine B (RhB) and Cr (VI) from aqueous solution, showing a maximum adsorption capacity reached up to 40.78 mg g-1 and 38.01 mg g-1, respectively. The kinetics and equilibrium of adsorption process were found to follow the pseudo-second-order kinetic and Langmuir isotherm models. Notably, the BiOI microspheres have excellent photocatalytic regeneration capability due to their intrinsically prominent photoresponse in visible light region. By meaning of providing a new insight into the design of new generation adsorbent that could combine adsorption and solar-driven photocatalysis, the synthesized BiOI microspheres are very promising for the large-scale industrial application for water treatment.

Mn-doped CeO2 flower-like microstructures have been synthesized by a facile one-step composite-hydroxide-mediated method. The structure, morphology, optical and the surface properties of Mn doped CeO2 have been investigated by X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), UV-Vis absorption spectroscopy and X-ray photoelectron spectroscopy (XPS). The XRD results confirmed the successful incorporation of Mn into the CeO2 lattice through the formation of face-centered cubic solid solution. The photocatalytic activities of the catalysts were evaluated by measuring the photodegradation efficiency of Rhodamine B (RhB) under ultraviolet light irradiation. With an optimal molar ratio of 1% in Mn/CeO2 the highest rate photodegradation was achieved under the experimental conditions. The enhanced photocatalytic activity can be attributed to the incorporation of multivalent Mn in CeO2 promoted the separation of photogenerated charges, inhibited the recombination of photogenerated carriers, and thus prolonged the charges lifetime to participate in the photocatalytic reaction.

Cu2(OH)PO4 microstructures were synthesized by the hydrothermal method using three different types cupric salts (Cu (NO3)2, CuSO4, Cu(CH3COO)2) as raw materials. The X-ray diffraction (XRD), scanning electron microscopy (SEM) and UV-visible-NIR absorption spectra were used to characterize the as-obtained products. The different anions (SO42-, CH3COO-, NO3-) have different shapes and polarities, which can generate different interactions in reaction bath, induced the difference of structure and morphology of the prepared Cu2(OH)PO4. The Cu2(OH)PO4 microstructures prepared form Cu(NO3)2•3H2O showed the best photocatalytic activity induced by near-infrared light to degrade 2,4-dichlorophenol (2,4-DCP) solution. Our work suggests that the active morphological surfaces as well as different coordination environments for the metal ions has an important influence on the photocatalytic performance of Cu2(OH)PO4 microstructure.

The composite Ag3PO4/CeO2 photocatlyst, a novel p-n type heterojunction, has been successfully fabricated through a facile hydrothermal process combined with a successive in situ precipitation technique. The X-ray diffraction (XRD), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM) and UV-visible diffuse reflectance spectra (DRS) were used to characterize the as-obtained products. The SEM and TEM image show that CeO2 particles have been successfully loaded and well distributed in the surface of Ag3PO4. The photocatalytic activities of the p-Ag3PO4/n-CeO2 heterojunctions were investigated for their efficiency on the degradation of Rhodamine B (RhB) under ultra-violet light and visible light irradiation, and the results showed that the p-Ag3PO4/n-CeO2 heterojunctions possessed remarkable photocatalytic activities. The enhanced photocatalytic activity can be attributed to the extended absorption in the visible light region resulting from the Ag3PO4 and the effective separation of photogenerated carriers driven by the internal electrostatic field in the junction region.

AbstractA highly efficient photocatalyst Ag3PO4/Ag was prepared by a one-step low temperature chemical bath method. The reflectance spectra (DRS) indicated Ag3PO4/Ag had strong absorption in visible light region. The synthesized Ag3PO4/Ag photocatalyst was used as the efficient photocatalysts for the photocatalytic degradation of Rhodamine B (RhB) under visible-light illumination which showed almost complete degradation (~ 98%) of RhB dye in 90 min. The negative surface of Ag3PO4/Ag photocatalyst also promoted the degradation of a cationic dye like methylene bule (MB; 78% in 90min), while the performance against an anionic dye like methyl orange was poorer (MO; 40% in 90 min). Compared to the pure Ag3PO4 photocatalyst, the Ag3PO4/Ag photocatalyst showed the enhanced visible light photocatalytic informance. The excellent photocatalytic performance is mainly ascribed to the surface plasmon resonance of Ag nanoparticles and a large negative charge of PO43- ions.