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In this study, Ce-doped ZnO photocatalysts are successfully prepared by using a simple and facile one-pot water bath method. The as-prepared samples are characterized by means of X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), ultraviolet–visible (UV–Vis) diffuse spectroscopy and Brunauer-Emmett-Teller (BET) surface area analysis. It is found that the as-synthesized Ce-doped ZnO possessed hollow porous structure, high surface areas and large pore volumes. The photocatalytic degradation efficiency (99%) of methyl orange (MO) with an optimal molar ratio of 0.3% Ce-doped ZnO is realized. The separation behavior of photogenerated electrons-holes pairs was investigated by surface photovoltage (SPV) and transient photovoltage (TPV) technique. The results illuminate that Ce element in Ce-doped ZnO tremendously promotes the separation of charges and inhibits the recombination of photogenerated charge carriers, corresponding to the excellent photocatalytic performance. [ABSTRACT FROM AUTHOR]

The construction of a Z-scheme heterojunction favors the improvement of the photocatalytic activity of photocatalysts. Herein, the LaVO 4 /Bi 3 O 4 Cl Z-scheme heterojunction was designed reasonably by the method of in situ growth. The obtained heterojunction was further used as a photocatalyst for the degradation of ofloxacin (OFX), an antibiotic, in wastewater. The degradation efficiency of OFX by the optimal sample (LBC-2) was 94.3 % and the values of k were about 114.7 and 2.4 times those of LaVO 4 and Bi 3 O 4 Cl, respectively. In addition, LBC-2 maintained high activity after 4 cycles. The significantly reduced recombination rate of carriers in LBC-2 was reflected by the results of the photoluminescence (PL), photocurrent (PC), and electrochemical impedance spectroscopy (EIS) studies. The degradation pathways of OFX were proposed accounting to the intermediates detected by liquid chromatography-mass spectroscopy (LC-MS). Toxicity estimations showed that the toxicity of some intermediates decreased. This work provides new insight into the development of Z-scheme photocatalysts for the removal of antibiotics as pollutants. • Novel Z-scheme LaVO 4 /Bi 3 O 4 Cl composite photocatalysts were synthesized. • LaVO 4 /Bi 3 O 4 Cl composites exhibited excellent activity for ofloxacin degradation. • The apparent rate constant for ofloxacin degradation was about 114.7 and 2.4 times as that of LaVO 4 and Bi 3 O 4 Cl. • Z-scheme heterojunction boosted the fast transfer of charge carriers. • The degradation pathway of ofloxacin was deduced. [ABSTRACT FROM AUTHOR]

Abstract: ZnO films with three different microstructures including hexagonal prisms, plates and rose-like twinned crystals were fabricated using chemical bath deposition with different concentration of gelatin. The growth mechanisms of ZnO films were discussed, and the gelatin played a vital role as a polyelectrolyte capping the formation of microstructures. The photoluminescence and Raman properties were found sensitive to the crystal morphologies of ZnO films. Significantly, the photodegradation efficiencies of methylene blue under UV light irradiation in the presence of ZnO films consisted of hexagonal prisms and rose-like twinned crystals were 95% and 96%, respectively. The excellent photocatalytic activities can be ascribed to the high oxygen vacancies concentration and high percentage of polar planes, and this result was important in addressing the origin of high photocatalytic activity. [Copyright &y& Elsevier]

Abstract: A visible light active photocatalyst was prepared through boron-doping by using sodium borohydride as boron source. Different from the previous boron-doped titania prepared at high temperature, our preparation was carried out at 55°C under hydrothermal condition. The as-prepared boron-doped titania was characterized by X-ray diffraction, transmission electron microscope, X-ray photoelectron spectroscopy, Raman spectroscope, diffuse reflection spectra and N2 adsorption–desorption measurements. The results showed that diboron trioxide phase appeared in the X-ray diffraction pattern of such photocatalyst. Compared to boron-doped titania synthesized by sol–gel method and pure TiO2, this novel photocatalyst exhibited stronger absorption in the visible region, and it also showed larger surface area. The photocatalytic activity was evaluated for degradation of Reactive Brilliant Red (C.I. Reactive Red 2) and 4-chlorophenol under visible light irradiation, respectively. The trend of photocatalytic activity was as follows: boron-doped titania (hydrothermal method)>boron-doped titania (sol–gel method)>pure titania>Degussa P25. [Copyright &y& Elsevier]

Abstract: A novel magnetically separable composite photocatalyst, titania-coated magnetic activated carbon (TMAC), was prepared by depositing of anatase titania onto the surface of magnetic activated carbon (MAC). The MAC was prepared by a simple route: directly adsorbing of magnetic Fe3O4 nanoparticles onto activated carbon. The prepared samples were characterized by XRD, scanning electron microscopy (SEM) and vibrating sample magnetometer (VSM). The photocatalytic activity of the samples was determined by degradation of reactive brilliant red X-3B under either UV or visible irradiation, and compared to Degussa P25. The composite photocatalyst can be separated easily from solution by a magnet, its photocatalytic activity in degradation of X-3B also has dramatic enhancement compared to that of P25 titania. The composite photocatalyst can also be reused with a little reduction of its photocatalytic activity. The degradation rates of X-3B were both higher than 80% after six cycles under UV and visible irradiation. [Copyright &y& Elsevier]

Direct Z-scheme Bi 3 TaO 7 –CdS semiconductor materials were synthesized via hydrothermal method. The activity of the composites was investigated by the ciprofloxacin (CIP) degradation under visible light irradiation. Bi 3 TaO 7 –CdS composite catalysts all exhibited enhanced photocatalytic performances compared to both single photocatalysts (Bi 3 TaO 7 and CdS). The characteristics of the morphology and structure, the photoelectric properties and the composition of chemical elements of these samples have been studied extensively. Besides, capture experiments demonstrated that superoxide radical and hole worked together for the CIP degradation. The optimal catalyst exhibited stable CIP degradation activity in four cycles repeating experiments. Finally, a possible Z-scheme charge migration mechanism was proposed for the Bi 3 TaO 7 –CdS composite photocatalysts. Three possible pathways were proposed for the CIP degradation based on the detected intermediates by LC/MS. This work provided a feasible idea for the further research of Z-scheme photocatalysts for the emerging contaminants degradation. • CdS/bismuth tantalate composite photocatalysts were synthesized for the first time. • The charge transfer followed Z-scheme mechanism. • The photocatalyst exhibited enhanced performance for CIP degradation of ciprofloxacin compared to Bi 3 TaO 7 and CdS. • The mechanism for the enhanced activity was discussed deeply. • The degradation pathways were deduced based on the detected intermediates. [ABSTRACT FROM AUTHOR]

LaFeO 3 /Bi 3 NbO 7 p-n heterojunction photocatalysts were prepared successfully through an in-situ growth method. The phase structure, optical property, morphology and microstructures of the obtained samples were studied by X-Ray diffractometer (XRD), Ultraviolet–visible absorption spectrum (UV–vis DRS), photoluminescence (PL) spectroscopy, transmission electron microscope (TEM), high resolution transmission electron microscope (HRTEM) and scanning electron microscope (SEM). The visible light responsive photocatalytic activity of as-obtained samples were investigated by the photo-reduction of Cr (Ⅵ). The effects of preparation conditions (proportion of BNO/LFO and temperature) on the activity were studied. Results showed that the as-obtained BNO-LFO-200-5 composite behaved the best photocatalytic activity (with rate constant of 0.0212 min−1) among all the obtained samples. The rate constant was about 42.4-times and 17.7-times as that of pristine BNO (0.0005 min−1) and LFO (0.0012 min−1), respectively. The enhanced photocatalytic property of the as-prepare LaFeO 3 /Bi 3 NbO 7 composites can be ascribed to the formation of p-n junction between BNO and LFO, which significantly increased the separation efficiency of photo-excited electron-holes. • A novel LaFeO 3 –Bi 3 NbO 7 p-n heterojunction photocatalyst was prepared for the first time. • The composites exhibited significantly enhanced activity for Cr (Ⅵ) photocatalytic reduction. • The heterojunctions promote the photo-generated carriers transmission and separation. [ABSTRACT FROM AUTHOR]

One of the current key issues in the photocatalysis is to obtain the band alignment of coupled semiconductor experimentally, which is the most significant aspect for understanding the efficient photocatalytic activity precisely. In this article, a BiVO 4 /BiOI{001} heterojunction was detected by the transmission electron microscopy (TEM). The results of electrochemical impedance spectroscopy (EIS) reveal that a higher efficiency of charge immigration across the electrode/electrolyte interface for the BiVO 4 /BiOI{001}. In addition, the electron lifetime was investigated by the Bode phase plots, which are responsible for the observed photocatalytic behaviors. As a result, the photocatalytic activities for rhodamine B (RhB) degradation and iodine ion oxidation are remarkably increased compared to the individual BiVO 4 and BiOI{001}. In fact, a direct band alignment in the BiVO 4 /BiOI{001} does not give well a logical interpreting on its photocatalytic behavior. However, through the valence-band offset formula, we demonstrated the exact band alignment of corresponding components in the BiVO 4 /BiOI{001}. This band alignment was further confirmed by the PL spectra, which CM2 with photo-oxidation (Mn 2+ ) is red shift and CM2 with photo-reduction (Ag + ) is blue shift compared with CM2. [ABSTRACT FROM AUTHOR]

A p-n-type Bi 5 O 7 I-modified porous g-C 3 N 4 nano-heterojunction is synthesized via a simple preparation technique using the template method and annealing-hydrothermal co-deposition method. The results of SEM, EDS, elemental mapping, XRD, TEM, XPS and FT-IR imply that the Bi 5 O 7 I nanoparticles were successfully deposited on the surface of the g-C 3 N 4 nanosheets. The photocatalytic activity of the as-prepared p-n-type nano-heterojunction remarkably exhibits an enhancement of 30 times that of the unmodified samples. Furthermore, the photocatalytic degradation enhancement mechanism has been studied, which could be ascribed to the p-n-type nano-heterojunction and lamellar-porous structure of the g-C 3 N 4 . [ABSTRACT FROM AUTHOR]

Novel hierarchical flower-like SnO 2 (HFL-SnO 2 ) nanostructures are successfully synthesized through the hydrothermal method. We find that the hierarchical architectures of SnO 2 is assembled by a number of regular-shaped nanosheets, which are cross-linked in the interior of the micro-flower. The product also has a high specific surface area of about 78.8 m 2 g −1 . Based on the nucleation and self-assembly process, a possible formation mechanism is proposed. The effects of SDS and NaCl on the product are also studied. Moreover, the product exhibits excellent photocatalytic activity and take possession of good stability and reusability under visible light. This study provides valuable experimental data for further study of nanomaterials and their photocatalytic properties. [ABSTRACT FROM AUTHOR]

In the present work, a series of layered BiOBr/g-C 3 N 4 heterojunction photocatalysts were prepared via a simple reflux process, and their photocatalytic performance was investigated by the degradation of rhodamine B (RhB) and bisphenol A (BPA) under visible light irradiation. It was found that BiOBr nanoplates were deposited on the external surface of g-C 3 N 4 nanosheets (CNNS) and the tightly contacted interface was formed between two components, giving rise to a 2D porous layered heterojunction structure with a high specific area. It was found that BiOBr nanoplates coupled with the proper amount of CNNS exhibited an excellent photocatalytic performance due to the combined effects of layered heterojunction, high specific surface area and porous structure, which lead to the high efficiency of light harvesting and charge separation. The active species of OH is the most crucial one while h + and O 2 − contributed to a lesser extent in RhB and BPA photocatalytic degradation. Based on the direct evidence of the formed OH, O 2 − and h + active species detected by active species capture experiment and ESR spectra, a Z-scheme photocatalytic mechanism was proposed for the charge separation. The present work may provide an insight for designing novel layered Z-scheme heterojunction photocatalysts with a high performance. [ABSTRACT FROM AUTHOR]

Co-utilization of solar and mechanical vibration energy via the piezo-photo bicatalysis is a new-emerging strategy for the management of environmental pollution. The combined bicatalysis is always expected to have a higher degradation rate than the sole catalysis. In this work, piezocatalysis coupled with photocatalysis has been applied to Bi 4 Ti 3 O 12 nanoflakes to check their synergistic effect. It was found that the dual catalysis including sonication exhibits an inferior degradation rate to the only piezocatalysis, which is contrary to the results reported in many references. However, if the piezoelectric stress is only afforded by a mechanical stirrer, the combined piezo-photo bicatalysis has a remarkable synergistic enhancement effect than the individual one. The radical trapping experiments were performed to identify the reactive active species involved in the decomposition of Rhodamine B (Rh B). The competition or cooperation of main active species in dual catalysis is suggested to clarify the underlying mechanism dominating the hybrid bicatalysis degradation efficiency. Additionally, the universality of the mechanism is also confirmed for treating Methyl Blue (MB) and Methyl Orange (MO). • Bi 4 Ti 3 O 12 nanoflakes were prepared by hydrothermal method. • Bi 4 Ti 3 O 12 was chosen as a model catalyst to explore coupling effect of photocatalysis and piezocatalysis. • Synergy between piezocatalysis and photocatalysis doesn't always take effect, depending on specific piezocatalytic manner. • Competition or cooperation of main active radicals is suggested to play a key role in determining synergetic efficiency. [ABSTRACT FROM AUTHOR]