Gangqiang Zhu

One-step solvothermal synthesis of Fe-doped BiOI film with enhanced photocatalytic performance

Ultrathin nanosheets consisting of Fe-doped BiOI were obtained on a FTO (SnO2:F) glass substrate via a simple solvothermal process. High-resolution transmission electron microscopic analysis indicates that the ultrathin nanosheets are exposed with {001} facets. The Fe-doped BiOI film has a higher photocatalytic activity for degrading Rhodamine B under visible light irradiation in comparison with the undoped BiOI films. The photocatalytic activity reached a maximum when the Fe doping concentration was 7%. It is believed that an optimal concentration of Fe3+ ions improves the electron–hole separation efficiency, hence improving the degradation rate of Rhodamine B. Scavenger test results indicate that the photo-generated h+ and ˙O2− play an important role in the degradation of Rhodamine B. A possible photocatalytic degradation mechanism for Rhodamine B by Fe-doped BiOI film is presented.

Controlled synthesis and enhanced luminescence of BiOCl:Eu3+ ultrathin nanosheets

BiOCl:Eu3+ ultrathin nanosheets were synthesized through a facile solvothermal method with the assistance of polyvinyl pyrrolidone. The ultrathin nanosheets showed a size ranging from 50–100 nm and a height of 2.9 nm, which is about four [Cl–Bi–O–Bi–Cl] layers. In addition, the luminescence properties and mechanism were investigated in detail, and compared with that of the nanoplate. It was found that the luminescence intensity for the BiOCl:Eu3+ ultrathin nanosheet was 6 times stronger than that of the nanoplate. Importantly, the oxygen vacancies act as a luminescence centers, and there was effective energy transfer from BiOCl ultrathin nanosheets to Eu3+ ions. In BiOCl:Eu3+ ultrathin nanosheets, white-light emission was observed under near-ultraviolet (NUV) excitation. These BiOCl:Eu3+ ultrathin nanosheets exhibit great potential as color-emitting phosphors for white light-emitting diode applications.

Synthesis of plasmonic enhance sphere-like Ag/AgI/Bi5O7I photocatalysts with improved visible-light responsive activity under LED light irradiation

Coupling surface plasmon with semiconductor has been demonstrated to be an efficient strategy for improving the photocatalytic performance of the photocatalyst. The sphere-like Ag/AgI/Bi5O7I composites were synthesized by a hydrothermal-decomposition process, followed by an in-situ ion exchange reaction. Under LED lamp irradiation (400u2009<u2009λu2009<u2009800xa0nm), the as-prepared Ag/AgI/Bi5O7I displayed a great enhancement in photocatalytic activities for the degradation of organic dyes (Rhodamine B and methyl orange), as compared with the pure orthorhombic phase Bi5O7I. The scavenger test results indicated that the photo-generated h+ would play an important role in the degradation of organic pollutants. Moreover, the Ag/AgI/Bi5O7I nanocomposite generates high photoactivity in the cycling photocatalytic test. According to the experimental results, the possible photocatalytic degradation mechanism of Ag/AgI/Bi5O7I was also proposed. From our perspective, this advantage is mainly ascribed to two aspects: (i) the surface plasmon resonance effect of Ag nanoparticles; (ii) the highly efficient separation of electrons and holes through the closely contacted interfaces in the Ag/AgI/Bi5O7I system.

Fullerene modification of Ag3PO4 for the visible-light-driven degradation of acid red 18

This work synthesized a C60/Ag3PO4 composite via the modification of Ag3PO4, by incorporation of an acid treated fullerene (C60), with the aim of improving the photocatalytic activity and stability of Ag3PO4. XRD, SEM, Raman, XPS, PL, and UV-vis DRS were used to study the structural characteristics of the obtained photocatalysts. Acid red 18 (AR18) was adopted to evaluate the photocatalytic activity of the as-prepared photocatalysts under visible light irradiation. The results showed that C60 was successfully hybridized with Ag3PO4, and the C60/Ag3PO4 composite showed higher photocatalytic activity and better stability than Ag3PO4. The enhancement of photocatalytic activity strongly depended on the amount of C60 on Ag3PO4, and the optimum amount was found to be a weight ratio of 2% (C60/Ag3PO4). Superoxide radical anions (O2˙−) were confirmed to be the main participants in the degradation of AR18, determined by the active free radical capture experiments, and O2˙− production by 2% C60/Ag3PO4 was nearly 1.5 times higher than that by Ag3PO4. The superior photocatalytic activity and stability of C60/Ag3PO4 could be attributed to the presence of C60, which can not only be used as an electron acceptor for photo-induced electrons from Ag3PO4 to reduce the recombination of photo-induced electron–hole pairs, but also to improve O2˙− production during the photocatalysis process.

Preparation of hollow Ag/AgCl/BiOCl microspheres with enhanced photocatalytic activity for methyl orange under LED light irradiation

Hollow Ag/AgCl/BiOCl microspheres photocatalysts have been successfully fabricated by anchoring Ag/AgCl nanoparticles on the surfaces of BiOCl microstructures. The as-synthesized composites greatly enhanced photocatalytic performance in the degradation of methyl orange under LED light irradiation, which was much higher than the Ag/AgCl or pure BiOCl. The photocatalytic mechanisms were analyzed by active species trapping experiment, where the photogenerated hole played critical roles in the reacting process. Our results revealed that the surface plasmon resonance of metallic Ag and heterojunction of Ag/AgCl/BiOCl photocatalysts had a great effect on the photocatalytic activity.

Photochemically Induced Electron Transfer: Simultaneously Decolorizing Dye and Reducing Cr(VI)

Hexavalent chromium (Cr(VI)) and dyes are of particular environmental concern and need to be removed from water urgently due to their high toxicity. Herein, we explored the possibility of electron transferring from dye Orange II (OII) to Cr(VI) under UV and simulated solar light irradiation, expecting to simultaneously decolorize dyes and reduce Cr(VI). Experimental results show that light irradiation can partially decolorize OII but has no ability to reduce Cr(VI) in solution only with OII or Cr(VI). However, both dyes and Cr(VI) can effectively and simultaneously be decolorized and reduced in the solution containing both OII and Cr(VI) under light irradiation, and a low pH level and high OII/Cr(VI) concentration ratio significantly favor the co-removal. Additionally, insoluble organo–Cr(III) complexes identified by FTIR and XPS characterization were generated during the reaction. These complexes are beneficial to the removal of chromium and total organic carbon from water. The possible degradation pathway of OII is further proposed based on the detection of degraded products by GC-MS analysis. The results of this work offer an approach for simultaneously removing multiple contaminants.