Feng Fu

Design and construction of the sandwich-like Z-scheme multicomponent CdS/Ag/Bi2MoO6 heterostructure with enhanced photocatalytic performance in RhB photodegradation

A sandwich-like Z-scheme tricomponent CdS/Ag/Bi2MoO6 photocatalytic system was rationally designed and successfully fabricated, in which Ag was loaded onto Bi2MoO6 microspheres by a facile photoreduction method and CdS was subsequently deposited onto the surface of Bi2MoO6 and Ag/Bi2MoO6 through a deposition–precipitation method. During this process, a series of Ag/Bi2MoO6 and CdS/Bi2MoO6 were also prepared. All the composites were characterized by XRD, TEM, SEM, EDX, XPS, UV-vis DRS, and IR spectra to confirm the successful integration of Ag or (and) CdS with Bi2MoO6, the alteration of morphology and the formation of a new phase before and after Ag or (and) CdS loading. The degradation of rhodamine B (RhB) dye under visible light irradiation (>420 nm) revealed that the CdS/Ag/Bi2MoO6 composite exhibited a highly visible-light-responsive photocatalytic performance compared to single Bi2MoO6 or CdS and dual Ag/Bi2MoO6 or CdS/Bi2MoO6. The enhanced photocatalytic performance of CdS/Ag/Bi2MoO6 was ascribed to its special structure – a typical Z-scheme photocatalytic system, in which Ag nanoparticles directly connected to the surface of CdS and Bi2MoO6 to form a solid–solid interface (ohmic contact), acting as a conductor that greatly shortened the distance for photogenerated electron transfer and combined photogenerated electrons from the CB of Bi2MoO6 with the photogenerated holes from the VB of CdS through ohmic contact, and thereby led to the efficient separation of photogenerated electrons and holes and showed stable and strong reducibility and oxidizability. Moreover, the surface plasmon resonance effect of metallic Ag nanoparticles also played an important role in the enhanced photocatalytic performance of RhB degradation under visible light irradiation. Furthermore, investigations on photoluminescence and photoelectrochemical properties also demonstrated indirectly the highly efficient separation of photogenerated electrons and holes in the Z-scheme CdS/Ag/Bi2MoO6 photocatalytic system. This new Z-scheme photocatalytic system will be applied to more photoreactions in further exploration.

La and F co-doped Bi2MoO6 architectures with enhanced photocatalytic performance via synergistic effect

Novel La and F co-doped Bi2MoO6 architectures were first successfully synthesized via a facile solvothermal process, and characterized using XRD, SEM, TEM/HR-TEM, XPS, EDS, UV-Vis DRS and PL spectra. The enhanced photocatalytic activities of La and F co-doped Bi2MoO6 architectures were evaluated by the photodegradation of rhodamine B (RhB) under visible-light irradiation. The results demonstrated that the F-1.0 at% La–Bi2MoO6 photocatalyst exhibits significantly enhanced photocatalytic activity, which is 6.54 times higher than that of pure Bi2MoO6. The cause can be attributed to the co-incorporation of La and F into Bi2MoO6 broadening the absorption in the visible-light region and thereby leading to the formation of new energy levels on top of the valence band of F–La–Bi2MoO6, and on the other hand, the synergistic effect of F and La, in which F doping led to the increase of absorptivity of F–Bi2MoO6 and acted as an n-type impurity to supply a hole carrier. The doped La3+ ions act in a key role to capture and transfer/release the photogenerated electrons for conversion from O2 to ·O2− to delay the recombination of the photogenerated electrons and holes, greatly suppressing the recombination of photogenerated electron–hole pairs and thus significantly improving photocatalytic activity in RhB photodegradation. The radical capture experiment confirmed that h+ and ·O2− were the main active species and were responsible for RhB photodegradation. Moreover, on the basis of the PL spectra, active species trapping detection and photocurrent response experiments, the mechanism of the enhanced photocatalytic activity for F–La–Bi2MoO6 was proposed.

AgBr nanoparticles decorated BiPO4 microrod: a novel p–n heterojunction with enhanced photocatalytic activities

AgBr nanoparticles loaded BiPO4 microrods have been successfully synthesized via a facile deposition–precipitation method. XRD, FE-SEM, TEM, EIS, UV-Vis-DRS techniques were employed to characterize the phase composition, morphology and light absorption properties of the as-synthesized samples. Methylene blue (MB) and phenol (Ph) were selected as model pollutant to investigate the photocatalytic activity of the as-synthesized samples under visible-light irradiation. The experimental results show that different amount of AgBr on BiPO4 exhibit an obvious effect on the degradation of MB and the optimum molar ratio of AgBr and BiPO4 is 1 : 10. In particular, the photocatalytic activity of AgBr/BiPO4 is superior to the activities of two individual photocatalyst, indicating the presence of a synergic effect between two component in AgBr/BiPO4. On the basis of photocatalytic results and energy band diagram, the activity enhancement mechanism of AgBr/BiPO4 composite has also been investigated. The p-type semiconductor AgBr and n-type semiconductor BiPO4 can match each other and form a novel p–n heterojunction, thus increasing the photogenerated electron–hole pair separation efficiency. Therefore, this work provides some help for the design of novel and efficient BiPO4-based photocatalyst with multi-components for enhancing visible-light-driven photocatalytic activity.

Porous BiOBr/Bi2MoO6 Heterostructures for Highly Selective Adsorption of Methylene Blue

Porous BiOBr/Bi2MoO6 (Br/Mo) heterostructures were designed and successfully fabricated, in which BiOBr nanoparticles were deposited on the surface of the secondary nanoplate of three-dimensional porous Bi2MoO6 architectures through a deposition–precipitation process. The as-prepared Br/Mo heterostructures were used as an adsorbent to remove methylene blue (MB) from aqueous solution. The batch adsorption results indicated that 50.0 wt % Br/Mo heterostructures show an enhanced adsorption capacity compared with pure Bi2MoO6 and BiOBr. The effects of initial solution, initial concentration, and contact time were systematically investigated. The optimum adsorbent amount and the pH value were determined to be 0.8 g L–1 and 2, respectively. Meanwhile, the experiments also revealed that porous Br/Mo heterostructures possess higher preferential adsorptivity for MB than that for methyl orange (MO–) and rhodamine B (RhB+). The dynamic experimental result indicated that the adsorption process conforms to the pseudo-second-order kinetic model. Weber’s intraparticle diffusion model indicated that two steps took place during the adsorption process. Thermodynamic analysis results showed that the adsorption is a physisorption process, which conforms to the Langmuir isotherm model. Additionally, the possible adsorption mechanism was also investigated. The present study implied that Br/Mo heterostructures are promising candidates as adsorbents for MB removal. Therefore, fabrication of semiconductor-based heterostructures could be a strategy to design new efficient adsorbents for the removal of environmental pollutants.

Synthesis of Ag, Pd-Loaded Bi2WO6 and its Photocatalytic Activities

Ag, Pd loaded Bi2WO6 photocatalyst were prepared via a photoreduction process and characterized with UV-Vis-DRS, XRD and FE-SEM. The photocatalysis experimental results indicated that the photocatalytic activity of Ag-loaded Bi2WO6 was greatly enhanced compared with pure Bi2WO6, and the content of silver has an impact on the catalytic activity of Ag-loaded Bi2WO6 photocatalyst. The loaded Ag and Pd acts as the electron receptor on the surface of Bi2WO6, which inhibits the recombination of photogenerated charge carrier between Ecb to the Evb in the Ag-loaded Bi2WO6. As a result, the reduction of electron-hole recombination decreased, which could significantly improve the photocatalytic activity.

Synthesis of Fe3+ Doped Bi2MoO6 Nanoplate and its Performance on Photocatalytic Degradation of Salicylic Acid

Fe3+ doped Bi2MoO6 photocatalyst was successfully synthesized via a hydrothermal process using Bi (NO3)3 and (NH4)6 Mo7O244H2O as starting materials. XRD, SEM and UV-Vis absorption spectrum techniques were employed to characterize the phase composition and spectrum properties of the as-synthesized samples. Salicylic acid was selected as a model pollutant to investigate the effect Fe3+ doping on the photocatalytic activity of as-synthesized Bi2MoO6. The experimental results indicated that Fe3+ element doping can enhance the photocatalytic activity of Bi2MoO6 photocatalyst. When the amount of Fe3+ doped in Bi2MoO6 is 0.5%, the photocatalyst exhibits the best photocatalytica activity. The doped Fe3+ doped into the crystal lattice of Bi2MoO6 photocatalyst act as the electron traps and facilitates the separation of the separation of photogenerated electron-hole pairs due to its electron deficient. Thus, Fe3+ doping improve the photocatalytic with great efficiency.

Preparation of Silver-Doped TiO2 Photoatalyst via a Simple Sol-Hydrothermal and their Visible Light Photocatalytic Activity

Silver-doped nano-TiO2 photocatalyst were synthesized via a simple hydrothermal route. The samples were characterized by XRD, XPS, FE-SEM and UV-Vis absorption spectrum techniques. Rhodamine B was selected as the model-pollutant to evaluate the photocatalytic activity of the samples. The XRD results indicated that the Ag-doped TiO2 were pure anatase phase. The UV-Vis spectroscopy revealed that the Ag doping can increase the absorption intensity of TiO2 in the visible region, which results in the improving the photocatalytic activity of TiO2 photocatalyst. Photocatalytic experimental results revealed that Ag-doping TiO2 catalyst shows the enhancement photocatalytic activity.

Investigation of Photocatalytic Oxidative-Extraction Desulfurization of Simulation Gasoline

Photocatalytic Oxidative-Extraction Desulfurization (Photo-cat-EODS) of thiophene, the main sulfur-containing compound of catalytic cracking (FCC) gasoline, has been investigated in heterogeneous photocatalysis process using WO3/ZnO composite as photocatalyst and air was used as the oxidant. Extraction process was also employ followed by the photocatalytic oxidative process to remove the oxidative products using acetonitrile as the extractant. Furthermore, orthogonal experiments method was used to optimize the processing parameters.

Microwave-Assisted Hydrothermal Synthesis of Ag/BiVO4 Architecture with Enhanced Photocatalytic Activities

BiVO4 microcrystals were prepared via a microwave-assisted hydrothermal process. Ag loaded BiVO4 photocatalyst was prepared by a photoreduction process. XRD, UV-Vis-DRS and FE-SEM techniques were employed to investigate its’ phase composition, absorption property and morphology. The photocatalytic activity of the as-prepared samples was evaluated by the degradation ratio of Rhodamine B. The result indicated that the as-synthesized BiVO4 are spherical microcrystals built up by square nanoplates. After Ag nanoparticles deposite, the photocatalytic activity of BiVO4 was greatly enhanced. Furthermore, the photoctalytic activity enhancement mechanism was also discussed.