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This study presents the first evidence for FeOx intra-gap states on Bi2WO6- magnetized materials enhancing the Norfloxacin (NFX) degradation with respect to Bi2WO6 within acceptable times under indoor visible light (< 5 mW/cm(2)). The kinetically faster photocatalyst Bi2WO6-FeOx contained magnetite (Fe3O4). This material lead to NFX removal within one hour and was able to degrade NFX showing a stable performance over many cycles. Evidence for the Bi2WO6-FeOx photocatalyst behaving predomonantly as a semiconductor is described in this study. Evaluation of the magnetic field effect due to the FeOx intra-gap states and the applied light intensity are correlated with acceleration of the NFX-degradation kinetics. Bi2WO6-FeOx samples show a weak photoluminescence. The pH of the solution was monitored in situ and became more alkaline by 0.3 units within the time of NFX degradation. Reactive oxygen species (ROS) have been identified to account for this observation and a preliminary mechanistic scheme is suggested consistent with the experimental runs involving redox reactions. Several surface techniques have been used to characterize the nanoparticles (NPs) surfaces of the materials used during the course of this study. Magnetic photocatalysts are shown to have a potential for practical applications compared to more traditional methods currently used in the separation of dispersed catalysts at the end of environmental cleaning processes.

In this work, we synthesized highly porous reduced graphene oxide foams, presenting augmented antibacterial activity in presence/absence of peroxymonosulfate (PMS). To date, this is the first investigation of photocatalytic PMS disinfection by 3D-rGO materials. The foams were prepared through hydrothermal (3DG-W) and solvothermal method (3DG-EG), and analyzed by SEM, PXRD, FTIR, Raman spectroscopy and BET. Hydrothermally synthesized aerogels (3DG-W) were better organized and had higher specific surface area. The higher ratio of I-D/I-G in 3DG-W showed the greater removal of oxygen functional groups, larger density of structural defects and a smaller average size of the sp(2) domains. Although in the dark PMS activation by 3DG and the subsequent bacterial inactivation likely proceeds via a non-radical pathway, under visible light, the bacterial inactivation rate for 3DG-W was similar to 3 times higher than that of 3DG-EG and radical pathways are dominant. The generated germicidal reactive species were identified using appropriate scavengers and accordingly, an overview of the occurring photocatalytic and PMS activation pathways is discussed, while the mechanisms leading to bacterial inactivation are hereby detailed.

Bi2WO6 is considered an effective photocatalyst, even under the visible part of the solar spectrum, and recent advances in the modification of its structure leave promise for harnessing its enhanced effectiveness. Our experimental E. coli disinfection results have shown that the flower-like morphology brought considerable enhancement to the overall performance over the nanoparticle form. To clarify the photocatalytic mechanism of Bi2WO6, a combination of experimental and computational methods has been employed to investigate the surface properties of Bi2WO6 nanosheets self-assembly flower-like architecture. Although experimental evidence has determined the band edge positions of the as-synthesized samples, so as to address the photocatalytic properties, the mechanistic basis of this concept remains unclear. The calculation results demonstrated here deepen our understanding and indicate the potential of surface configuration to considerably alter the electronic structure and related photocatalytic properties of Bi2WO6 nanosheets. Firstly, we consider a range of surface slab models of Bi2WO6 (010) facet and calculate their surface Gibbs free energies. Having determined that the bi-termination is energetically more favorable by ab initio atomistic thermodynamics, hydrogen passivated termination was proved to be most stable. Through the analysis of the electronic band structure within the DFT-1/2 scheme and work function of the most stable termination, excellent agreement of experimental and theoretical predictions provided a meaningful understanding on the kinetic dependence of photocatalytic bacterial inactivation.