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This study focuses on the synthesis of a new high efficiency visible-light photocatalyst made of SnS 2 and conjugated derivative (CPVA) from thermal dehydration of polyvinyl alcohol (PVA), and the evaluation of its performance in photocatalytic reduction of aqueous Cr(VI). SnS 2 /CPVA nanocomposites were synthesized via the procedures of (i) mixing of SnS 2 nanocrystals and PVA in aqueous solution and evaporation of the aqueous solvent to generate SnS 2 /PVA nanocomposites, and (ii) thermal treatment of the SnS 2 /PVA nanocomposites for transforming their PVA into conjugated CPVA. The optimum conditions for synthesis of most efficient SnS 2 /CPVA nanocomposite were explored. The characterization by X-ray diffraction, Raman spectroscopy, infrared spectroscopy, X-ray photoelectron spectroscopy, high resolution transmission electron microscopy and elemental mapping indicated the formation of SnS 2 /CPVA nanocomposites. The photocatalytic experiments showed that SnS 2 /CPVA nanocomposite synthesized under the optimum conditions (SnS 2 /CPVA-1%-180 °C-2 h) had exceptionally higher photocatalytic activity than SnS 2 nanocrystals, physical mixture of SnS 2 nanocrystals and CPVA, SnS 2 /CPVC nanocomposite and TiO 2 /CPVA nanocomposite in the reduction of aqueous Cr(VI) under visible-light (wavelength > 420 nm) irradiation. The mechanism underlying the most enhanced photocatalytic activity of SnS 2 /CPVA-1%-180 °C-2 h was elucidated, based upon comparison between the optical, photoelectric and electrochemical impedance properties of SnS 2 nanocrystals and different SnS 2 /CPVA nanocomposites. Furthermore, the effects of photocatalytic experiment parameters (including dosage of photocatalyst, and initial pH and concentration of Cr(VI) aqueous solution) on the Cr(VI) removal efficiency by SnS 2 /CPVA-1%-180 °C-2 h were also studied. [ABSTRACT FROM AUTHOR]

Polyaniline (PANI) was adopted to modify SnS 2 to develop a novel efficient visible-light-driven photocatalyst. SnS 2 /PANI composite was synthesized via first mixing of SnS 2 and PANI in N,N-Dimethylformamide solution and subsequent evaporation of N,N-Dimethylformamide. The characterization by Raman and Fourier transform infrared spectroscopy demonstrated the production of SnS 2 /PANI composite. UV–vis diffuse reflectance absorbance spectra showed that the coupling with PANI enhanced the visible-light-absorbing capability of SnS 2 . The photoluminescence and electrochemical impedance spectra showed that SnS 2 /PANI composite was more efficient in the separation and transfer of photogenerated charges than SnS 2 . The photocatalytic tests showed that SnS 2 /PANI composite exhibited notably higher photocatalytic activity than SnS 2 in reduction of aqueous Cr(VI) under visible-light (λ > 420 nm) irradiation (the rate of photocatalytic reduction of Cr(VI) by SnS 2 /PANI composite was nearly 4.2 times that by SnS 2 ). The possible reasons underlying the enhanced photocatalytic activity of SnS 2 /PANI composite were also proposed. [ABSTRACT FROM AUTHOR]

Partially conjugated polyvinyl chloride (CPVC)-modified TiO 2 nanoparticles were synthesized by heating the composite of polyvinyl chloride and TiO 2 nanoparticles in air at 150 °C for 1 h (the optimal heating duration among the investigated 0.5 h, 1 h, 2 h, 3 h and 4 h to obtain the most efficient CPVC/TiO 2 composite). The characterization results from X-ray diffraction, Raman spectra, X-ray photoelectron spectroscopy and high resolution transmission electron microscopy confirmed the formation of TiO 2 nanoparticles modified with CPVC. The UV–vis diffuse reflectance spectra indicated that the as-synthesized CPVC-modified TiO 2 nanoparticles had remarkable visible-light-absorbing ability. The photocatalytic experiments demonstrated that the as-synthesized CPVC-modified TiO 2 nanoparticles exhibited high photocatalytic activity in the reduction of aqueous Cr(VI) under visible-light ( λ >420 nm) irradiation, whereas sole CPVC and TiO 2 nanoparticles exhibited no photocatalytic activity in the reduction of aqueous Cr(VI) under visible-light ( λ >420 nm) irradiation. [ABSTRACT FROM AUTHOR]

An alternative simple, economical and efficient acid-soaking method was proposed to improve the activity of g-C 3 N 4 for photocatalytic reduction of aqueous Cr(VI) in this work. The improvement was achieved simply by soaking g-C 3 N 4 (which was obtained by heating melamine in air at 550 °C for 4 h) in 5 mol/L HNO 3 or HCl aqueous solution for 2 h (the HNO 3 and HCl-treated samples were denoted as g-C 3 N 4 HNO 3 and g-C 3 N 4 HCl, respectively). The compositions, structures, Brunner–Emmet–Teller (BET) specific surface areas, Zeta potentials and optical properties of g-C 3 N 4 , g-C 3 N 4 HNO 3 and g-C 3 N 4 HCl were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, field emission scanning electron microscopy, N 2 adsorption/desorption isotherms, Zeta potential analyzer and UV–vis diffuse reflectance spectroscopy. The photocatalytic properties of g-C 3 N 4 , g-C 3 N 4 HNO 3 and g-C 3 N 4 HCl were tested in the reduction of aqueous Cr(VI) under visible-light ( λ > 420 nm) irradiation. It was observed that both g-C 3 N 4 HNO 3 and g-C 3 N 4 HCl exhibited higher photocatalytic activity than g-C 3 N 4 . The higher photocatalytic activities of acid-treated samples may be attributed to their larger BET specific surface areas, positive surface charges and larger adsorption capacities for Cr(VI). Furthermore, the soaking treatment with 5 mol/L HNO 3 aqueous solution can not only remove the Cr(III) species deposited on the surface of g-C 3 N 4 HNO 3 after use in photocatalytic reduction of aqueous Cr(VI), but also enhance the photocatalytic efficiency of g-C 3 N 4 HNO 3 in reuse. [ABSTRACT FROM AUTHOR]

This communication reports the development of a new efficient visible-light-driven composite photocatalyst comprising ZnFe 2 O 4 nanoparticles and conjugated polymer (CPVC) from the dehydrochlorination of polyvinyl chloride (PVC). ZnFe 2 O 4 /CPVC nanocomposites were synthesized via three main steps: (i) the synthesis of ZnFe 2 O 4 nanoparticles by a sol-gel method; (ii) the adsorption of PVC in tetrahydrofuran solution by ZnFe 2 O 4 nanoparticles to form ZnFe 2 O 4 /PVC nanocomposites; and (iii) the dehydrochlorination of PVC in the ZnFe 2 O 4 /PVC nanocomposites by heating at 150 °C for 2 h. X-ray diffraction, Fourier transform infrared spectroscopy and high-resolution transmission electron microscopy characterization revealed that the as-synthesized product was core/shell structured ZnFe 2 O 4 /CPVC nanocomposites. The photocatalytic results demonstrated that the ZnFe 2 O 4 /CPVC nanocomposites had much higher photocatalytic activity than ZnFe 2 O 4 nanoparticles in the reduction of aqueous Cr(VI) under visible-light (λ>420 nm) irradiation. Thus, ZnFe 2 O 4 /CPVC nanocomposites are promising for use as a new efficient visible-light-driven photocatalyst. [ABSTRACT FROM AUTHOR]

• Design and preparation of SnO 2 /SnS 2 /CPVC ternary composite as photocatalyst. • SnO 2 /SnS 2 /CPVC shows synergistically enhanced photoinduced charge separation. • SnO 2 /SnS 2 /CPVC has far higher visible-light photocatalytic activity. • SnO 2 /SnS 2 /CPVC shows good photocatalytic reusability and stability. • Useful for the development of new efficient ternary composite photocatalysts. A new high-efficiency ternary composite photocatalyst (SnO 2 /SnS 2 /conjugated polyvinyl chloride derivative (CPVC)) was designed based on the hypothesis that any two of its components can constitute type-II heterojunction, and its three components should have synergistic effect on the enhancement of photoinduced charge separation. SnO 2 /SnS 2 /CPVC ternary composite was prepared adopting an easy-to-implement four-step synthesis method. Photoluminescence and electrochemical impedance spectra showed that SnO 2 /SnS 2 /CPVC is more efficient than SnO 2 /SnS 2 , SnS 2 /CPVC, SnO 2 /CPVC and SnS 2 in the separation and transfer of photoinduced charges. Results from their photocatalytic reduction of Cr(VI) under visible-light irradiation indicated that SnO 2 /SnS 2 /CPVC has significantly higher visible-light photocatalytic activity than SnO 2 /SnS 2 , SnS 2 /CPVC, SnO 2 /CPVC, SnS 2 , CPVC and SnO 2. Moreover, SnO 2 /SnS 2 /CPVC also demonstrated good photocatalytic reusability and stability. This study not only has developed a new high-activity visible-light photocatalyst (SnO 2 /SnS 2 /CPVC), but is also useful for the design of other new ternary composite photocatalysts with synergistically enhanced visible-light photocatalysis. [ABSTRACT FROM AUTHOR]