The plasma Bi/Bi₂MoO₆/TiO₂ composite nanofibers were prepared via a facile one-step solvothermal method, using electrospun TiO₂ nanofibers as substrate, and glucose as reducing agent. The photocatalytic activity of the samples were evaluated by photodegradation of rhodamine B and 4-chlorophenol solution under visible light irradiation. The results showed that metal Bi nanoparticles were generated on the surface of Bi₂MoO₆ nanosheets via reduction of Bi ³⁺ in situ by glucose, meanwhile grew on the TiO₂ nanofibers surface. The photocatalytic activity of the Bi/Bi₂MoO₆/TiO₂ composites nanofibers can be further improved by depositing metallic Bi owing to its surface plasmon resonance. The RhB catalyzed by the sample was degraded by 95.8% under visible light irradiation for 50 min, and the degradation efficiency remained over 92% after 5 cycles while the 4-CP was degraded for 68.8% under visible light irradiation for 180 min. All above results suggest that the photocatalysts have good photocatalytic activity and stability.

MoS₂ quantum dots (QDs) decorated NH₂-MIL-125 (MoS₂ QDs/NH₂-MIL-125) heterostructures were successfully fabricated by a facile method. XRD results exhibit that NH₂-MIL-125 and MoS₂ form crystals in the synthesis process of MoS₂ QDs/NH₂-MIL-125 heterojunctions. TEM results demonstrated clearly that the MoS₂ Quantum dots with size of about 4 nm successfully disperse on the surface of NH₂-MIL-125 plate. Compared with bulk MoS₂ and NH₂-MIL-125, the MoS₂ QDs/NH₂-MIL-125 heterostructures exhibit enhanced photocatalytic performance in degradation of methyl orange under visible light irradiation, about 5.8 and 7.4 times higher that of pure bulk MoS₂ and NH₂-MIL-125, respectively. Meanwhile, MoS₂ QDs/NH₂-MIL-125 composites exhibit good stability and reusability during cycle experiment. The excellent photocatalytic activity of MoS₂ QDs/NH₂-MIL-125 heterostructures is attributed to the formation of heterojunctions between MoS₂ QDs and NH₂-MIL-125, Tacilitating separation of the photogenerated charge carries. PL results prove that MoS₂ QDs/NH₂-MIL-125 composites own lower recombination of photogenerated electrons and holes, resulting in superior photocatalytic ability.

Photocatalyst of N-doped Bi₂O₂CO₃ (N-BOC)/CdSe quantun dots (QDs) composite was sucessfully prepared for degradation of nitric oxide (NO), an indoor air pollutant. The results of X-ray diffraction, transmisssion electron microscopy and X-ray photoelectron spectroscopy showed that after combination with CdSe QDs structure and morphology of N-BOC remained the same as before combination. Photocatalytic degradation of NO showed that introduction of CdSe QDs significantly enhanced the removal ratio of NO. Moreover, the generating ratio of toxic byproduct NO₂ decreased to 1%, which indicated efficient inhibition for the toxic byproduct generation. From UV-Vis absorption spectroscopy and photoluminescence spectroscopy, the CdSe QDs showed promotion on light absorption, and inhibition of charged recombination of photo-induced carriers. More importantly, only signals of NO₃ ^- were captured in in situ DRIFTS measurements, whilst the signals from NO₂ could be barely detected during photocatalytic process. Superoxide radicals (O₂ ^-) and holes (h ⁺) are considered to be possible active species in the reaction, which dominate the oxidation process from NO to NO₃ ^-.

Visible-light-driven photocatalyst BiVO₄ was synthesized via a facile microwave-hydrothermal method using BiVO₃·5H₂O and NH₄VO₃ as raw materials. Crystal structure of BiVO₄ photocatalyst could be selectively controlled to be tetragonal or monoclinic by simply adjusting the pH of the precursor solution. The prepared samples were characterized by XRD, UV-Vis, Raman, and SEM. The mechanism of BiVO₄ formation with different crystal structures was discussed. Meanwhile, the photocatalytic performances of the prepared sample were evaluated by degradation of methylene blue and photocalytic oxidation of NO gas in air under visible light irradiation. The results showed that BiVO₄(z-t) microsphere was obtained when the precursor pH is 3-5, but when the pH is less than 2 or greater than 7, the as-prepared powders are BiVO₄(s-m) with polyhedron morphology. This may be due to the change of pH that could form transformation of vanadate and bismuth ion in the precursor solution, and then affect the formation process of BiVO₄, resuting in the change of crystal structure, morphology, crystal surface, and VO₄ tetrahedron of BiVO₄(s-m). The photocatalytic tests indicated that the activity of BiVO₄(s-m) was much better than that of BiVO₄(z-t). The BiVO₄(s-m) sample prepared at pH 9 exhibits excellent visible-light photocatalytic activity, because of its higher crystalline, preferentially exposed facts (040), and higher degree distortion of VO₄^3- tetrahedron.

Antimony trisulfide (Sb₂S₃) nanorods were successfully synthesized via hydrothermal method with the assistance of polyethylene glycol (PEG) and N,N-dimethylformamide (DMF), using natural stibnite as precursor. The effects of experimental parameters on the morphology and the properties of the obtained Sb₂S₃ were systematically studied, and the possible formation mechanism of Sb₂S₃ nanorods in the preparation process was also discussed. Phase, compositions, morphology and photoelectric properties of the products were investigated by a series of characterization methods. The photocatalytic activity of nano Sb₂S₃ on the degradation of methyl orange were investigated under the visible light irradiation. The results showed that the Sb₂S₃ nanoflakes formed after hydrothermal synthesis at 160℃ for 12 h, and the nanoflakes would transform into nanorods eventually after N₂-annealing at 400℃ for 1 h. The obtained Sb₂S₃ nanorods with a single crystal structure are typically 2~3 μm in length, 100~200 nm in width, which are direct semiconductor with band gap of 1.66 eV. Photocatalytic degradation rate of the obtained Sb₂S₃ nanorods on methyl orange under visible light irradiation is higher than that of commercial Sb₂S₃, which is up to 87.6% after 60 min degradation, exhibiting obvious visible-light activity.

A facile strategy for anatase titanium dioxide (TiO₂) nanoparticle preparation was proposed via a non-aqueous precipitation method. With the aid of glacial acetic acid, tetrabutyl titanate underwent non-hydrolytic reaction in solvent ethanol. Glacial acetic acid increased polarity of Ti-O and C-O bonds of tetrabutyl titanate, and promoted non-hydrolytic de-etherization poly condensation reaction to form Ti-O-Ti bond in the solvent. After refluxing at 80℃ for 24 h, the Ti-O-Ti bond was rearranged to form anatase TiO₂ nanoparticles with the particle size of 5 nm-20 nm and specific surface area of 169.4 m²/g, which exhibited good dispersion and excellent photocatalytic activity. The degradation rate against methyl orange under ultraviolet radiation for 2 h reached 99.81%, showing promising prospect in wastewater treatment process.

Improving catalysis efficiency and reducing production cost attract extensive interest for the study of photocatalyst. Herein a blue titania crystal with aluminum atoms modified on the surface was prepared by aluminum reduction and deposition. The blue titania displays a unique core-shell structure with crystallization nuclei inside and with oxygen vacancies and aluminum atoms outside. And the blue titania shows excellent photocatalytic and electrochemical performance under simulated sunlight. Under high vacuum, with vapored aluminum atoms being deposited on titania nanocrystals, Ti⁴⁺ is reduced to Ti³⁺, which creates a large number of oxygen vacancies on the surface. Additionally, moderate amounts of aluminum atoms coated on titania become photo-induced charge carrier traps, facilitating the separation and transport of charge carriers, which enhances the photocatalytic capability. TiO₂-Al_0.36 exhibits the best photocatalytic performance, degrading methyl orange in 8 min, and it shows excellent photochemical property with the photocurrent of 1.47 mA·cm^-2, which is more than 8 times as high as that of pristine titania (0.17 mA·cm^-2).

Pure triclinic porous FeVO₄ with multiple morphologies were fabricated by adopting hydrothermal strategy using Fe(NO₃)₃ and NH₄VO₃ as inorganic source and NH₃ solution as pH adjuster. The samples were characterized by means of techniques such as X-ray diffraction, scanning electron microscopy, and ultraviolet-visible diffuse reflectance spectroscopy. It was found that hydrothermal temperature and pH of the precursor solution exerted a great effect on the crystalline structure and the particle morphology of the product. Porous triclinic FeVO₄ nanorods were generated hydrothermally at 180℃ and pH of 4 or 7, sheet-like FeVO₄ was obtained at pH 4.0 and hydrothermal temperature of 120℃. However, the mixture of Fe₂O₃ (in majority) and FeVO₄ (in minority) was prepared when pH of the precursor solution was raised to 10 at 180℃ or the hydrothermal temperature was raised to 240℃ at pH 4.0. Among the FeVO₄ samples, porous FeVO₄ nanorods with the highest surface area of 10.4 m²/g exhibited the best visible-light-driven photocatalytic performance for the degradation of MO. It is concluded that such an excellent photocatalytic performance is attributed to its higher crystallinity, surface area, and surface oxygen vacancy density, porous structure, and lower bandgap energy.

Sheet-like agglomerates β-Bi₂O₃ were synthesized via an extraction-precipitation stripping-decomposition method using a leaching solution of bismuthinite as raw materials in acidic chloride media. Phase form of as-prepared Bi₂O₃ was confirmed by X-ray diffraction (XRD) and its morphology was observed by scanning electron microscope (SEM) and transmission electron microscope (TEM). Moreover, photocatalytic activity of the β-Bi₂O₃ was evaluated by measuring the degradation of Rhodamine B (RhB) under visible light irradiation. The results showed that the powders consisted of nanoflakes. The β-Bi₂O₃ exhibited a smaller band gap energy and larger absorbance edge than α-Bi₂O₃ and reported β-Bi₂O₃. In addition, 99.23% of the RhB was degraded under 4 h visible light irradiation and β-Bi₂O₃ was a fairly stable photocatalyst under the experimental conditions.

Multiferroic KBiFe₂O₅ was successfully prepared by a facile hydrothermal method. Its phase purity and morphology were investigated by powder X-ray diffraction (XRD) and field emission scanning electron microscopy (FE-SEM). The visible-light absorption was confirmed by UV-Vis diffuse reaction spectroscopy (UV-Vis DRS). Effect of pH value on visible-light-driven photocatalytic properties of KBiFe₂O₅ was evaluated by degrading rhodamine B (RhB) and methyl orange (MO). It can be found that lower pH value contributed to smaller average particle size. The D₅₀ of the sample at pH 7 is about 10 times larger than that at pH 2. Acid condition is beneficial to the dispersion of KBiFe₂O₅ nanoparticles, which leads to an enhanced photocatalytic performance. Photocatalytic activity of KBiFe₂O₅ is significantly improved by decreasing pH value of the solution, which is attributed to the promoted dispersion of catalyst particles in the suspension and the enhanced adsorption of dye molecules on the catalyst surface.

Novel visible-light-responsive Au/Bi₂WO₆ heterogeneous nanostructures were successfully prepared through in situ growth gold nanoparticles (Au NPs) on the second-structural nanosheets of three-dimensional (3D) Bi₂WO₆ via a facile photoreduction process. XRD, FE-SEM, HR-TEM, FT-IR, XPS, and UV-Vis-DRS spectra were employed to investigate the phase composition, morgphology and light-absorption properties of as-preapared samples. Rhodamine B(RhB) and phenol were selected as model pollutants to evaluate photocatalytic activities of samples. The experimental results reveal that the as-prepared Au/Bi₂WO₆ heterogeneous nanostructures exhibit much higher photocatalytic activities than pure Bi₂WO₆ for dye degradation. It is also revealed that 1.5at%Au/Bi₂WO₆ sample exhibit the best photocatalytic activities in the degradation process of RhB and phenol, the apparent rate constant is about 1.5 and 2.2 times as high as that of pure Bi₂WO₆ under visible light irradiation, respectively. Moreover, the trapping experiments results show that photogenerated hole (h⁺) and ·O₂^- serve as the main active species for the photodegradation of RhB over Au/Bi₂WO₆ heterogeneous nanostructures. The enhanced photocatalytic efficiencies of Au/Bi₂WO₆ heterogeneous nanostructures are attributed to the charge transfer from Bi₂WO₆ to the deposited Au NPs as well as their surface plasmon resonance (SPR) absorption, which enhance the migration efficiency of the electron-holes and retard the recombination of electrons-hole pairs. Au NPs decorated Bi₂WO₆ heterogeneous nanostructures have considerable potential applications in solar-driven wastewater treatment.

The g-C₃N₄/MoS₂ nanosheets/graphene oxide (GO) ternary composite photocatalyst was successfully prepared by a ball milling method. Its structure, morphology and optical property were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), UV-Vis absorption spectroscopy (DRS), and photoluminescence spectroscopy (PL), respectively. The results indicated that the heterogeneous structure of MoS₂ nanosheets and g-C₃N₄ were formed on the surface of GO. The photocatalytic activity of the photocatalyst was evaluated by degradation of organic Rhodamine B (RhB) under visible light irradiation. The ternary composite photocatalyst could degrade 96% of RhB within 120 min, about 3, 2.1 and 2.8 times higher than that of the g-C₃N₄, g-C₃N₄/MoS₂ composite and g-C₃N₄/GO composite. Based on the experimental results and the band structure, a possible charge transfer mechanism of ternary composite photocatalyst was proposed.

With unique electronic effect, TiO₂ nanoparticles can be used as photocatalysts to reduce or eliminate the organic pollutants only under irradiation of sunlight. It is, therefore, highly desirable to improve its dispersion and solubility to broaden its application in different fields especially in environmental conservation. Here provides a case of two-step method to prepare yellow transparent water-soluble TiO₂-ionic liquids hybrid nanomaterial. In this hybrid system, organic sulfonate groups as canopy provide “self-solvent” for the dispersion of the TiO₂ nanoparticles. This dispersion experiment results indicated that the water-soluble organic canopy in the TiO₂-ionic liquids hybrid nanomaterial offered good solubility in water and the TiO₂-ionic liquids hybrid nanomaterials used in-home decoration could be easily wiped away on the surface of furniture. Data from photocatalytic degradation efficiency for decomposing formaldehyde demonstrated that the hybrid nanofluids possessed excellent photocatalytic performance. The water-soluble TiO₂-ionic liquids hybrid nanomaterials could be a promising candidate for environmental conservation in the future.

In this study, a CQDs/BiPO₄ nanocomposite with enhanced visible-light absorption and charge separation was fabricated via a one-step hydrothermal reaction. The photocatalytic activity of the CQDs/BiPO₄ nanocomposite was evaluated by degradation of rhodamine B (RhB). The result showed that the CQDs/BiPO₄ composite exhibited superior photocatalytic performance to pure BiPO₄ under simulated solar light, as well as under visible light irradiation. Its enhanced photocatalytic performance could be ascribed to the excellent light harvesting properties, which increased utilization rate of solar energy, electron transfer efficiency and reservoir ability of the nanocompsites, facilitating the charge separation efficiency of the composite.

A novel NaTaO_3-xS_x catalysts were successfully synthesized by one-step hydrothermal method using Ta₂O₅ as starting material and Na₂S₂O₃ as sulfur source. Its catalytic mechanism and reaction process were tested by degradation experiment. The samples were characterized by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XRS), UV-Vis diffuse reflectance spectra (UV-Vis DRS) and X-ray diffraction (XRD). The results showed that the as-prepared S-doped NaTaO₃ did not display obvious variations to the surface charge and micro-morphology of NaTaO₃. UV-Vis diffuse reflectance spectrum analysis indicated that S^2- partially substitute of O^2- ions in the lattice to form Ta-S-Ta bonds, and the light response range of the doped NaTaO_3-xS_x samples extends to the visible region. The results of degradation experiment indicated that NaTaO_3-xS_x exhibited much higher activity than that of pure NaTaO₃. The reason is that in the crystal lattice of NaTaO_3-xS_x, S^2- ions replace part of the O^2-ions, which form a mixed valence band energy levels. The results of GC-MS showed that the monohydroxylated species (m/z = 304) results in the production at m/z = 156, 226 and 276, which is further degraded into species of m/z = 212 and 156. Finally, the photogenerated oxidative species forming over S-doped NaTaO₃ catalyst surface further decompose these intermediates into the final carbon dioxide and some non-toxic inorganic products (SO₄^2-, NO₃^- and NH₄⁺). In addition, in a ten-time recycling test, S-doped NaTaO₃ displayed reliable recycling photocatalytic performance, whose photocatalytic efficiency kept at a high level and only existed very slight drop, due to the loss of photocatalyst during the reclaiming process.