A novel, rapid and sensitive 4-chlorophenol (4-CP) photoelectrochemical (PEC) sensor was developed using ZnWO4/BiOCl{110} heterojunctions as sensing electrodes with BiOCl possessing dominated {110} facets. ZnWO4/BiOCl heterojunctions with tunable dominated crystal faces were successfully prepared through facile solvothermal methods in the mixed solvents of deionized water and ethylene glycol. The ZnWO4/BiOCl{110} heterojunction with the dominant {110} crystal plane shows stronger visible light absorption, higher photocurrent intensity, and its heterojunction structure can effectively suppress the recombination of photogenerated electrons and holes, which greatly improves the PEC performance when compared to pure ZnWO4, pure BiOCl, and ZnWO4/BiOCl{001}. The improved PEC activity of 5%ZnWO4/BiOCl{110} heterojunction resulted in a highly improved sensing performance for 4-CP detection, which includes low detection limits, wide detection ranges, good stability and specificity. Under optimal conditions, the 5%ZnWO4/BiOCl{110} PEC sensor affords a linear range from 1 to 10 mu M for 4-CP, with a detection limit of 0.36 mu M. The synergistic impacts of heterojunction structure and crystal plane structure on photogenerated carrier transfer characteristics and light absorption performance may be better understood as a result of this research.

BiPO4/{110}BiOBrxI1-x (x = 0, 0.25, 0.5, 0.75 and 1) nanocomposites with p-n heterojunction structure, which predominantly expose the {110} facet, were successfully created using a straightforward solvothermal technique. Multiple techniques have been implemented to characterize and analyze the produced photocatalyst. The degradation of phenol was used to assess their photocatalytic effectiveness. The best performing sample was the 5% BiPO4/{110}BiOBr0.75I0.25 nanocomposites, achieving complete decomposition of phenol within 60min. Photocurrent measurements revealed that the enhanced performance is attributable to the creation of the heterojunction and the dominant {110} facet, which collectively suppress the recombination of photogenerated charge carriers. Furthermore, the heterojunctions' optical absorption characteristics were tunable by varying the Br/I molar ratio. Superoxide radicals (& sdot;O-2(-)), holes (h(+)) and hydroxyl radicals (& sdot;OH) were identified as the primary active species responsible for photocatalytic degradation via radical trapping experiments.

The BiOIO3/BiOCl heterojunctions with different dominated facet, BiOIO3/{110}BiOCl and BiOIO3/{001} BiOCl, were prepared through facile solvothermal/hydrothermal methods with ethylene glycol/deionized water as solvents. As. prepared BiOIO3/BiOCl photocatalysts were characterized by X-ray diffraction, scanning electron microscope, energy. dispersive spectroscopy, and UV-Vis diffuse reflectance spectra. The photocatalytic activity of BiOIO3/BiOCl heterojunctions was evaluated by photo-catalytically decomposing rhodamine B and phenol in an aqueous solution under visible light irradiation. The results showed that 25% BiOIO3/{110}BiOCl heterojunctions exhibited the highest photocatalytic efficiency. The degradation of RhB over 25% BiOIO3/{110}BiOCl was 98.7% after 15 min of light irradiation. And 100% phenol can be degraded after irradiation for 150 min. The better photocatalytic performance of BiOIO3/{110}BiOCl may be attributed to the strong absorption of the visible light, the heterojunction structure, and the efficient separation of photo-generated carriers benefiting from the dominated (110) facet of BiOCl. The superoxide radicals (center dot O-2(-)) and holes (h(+)) are the main active species in the photocatalytic pro. cess. Moreover, a reasonable mechanism for enhanced photocatalytic performance was also discussed based on the experimental results.

Formaldehyde is one of the most hazardous and typical indoor VOCs air pollutants. Asymmetric AgIO3 was respectively composited with 3D hierarchically structured BiOBr and 2D BiOBr nanosheets to photodegrade gas-phase formaldehyde. Ag/AgIO3/BiOBr(CMC) demonstrated better photocatalytic performance than Ag/AgIO3/BiOBr owning to the role of biomass solvent sodium carboxymethyl cellulose in increasing the specific surface area, reducing the band gap and changing the dominant facets. Moreover, Ag nanoparticles coming from the reduction in AgIO3 were confirmed by XRD, SEM and XPS. The surface plasma resonance effect of Ag NPs improved the efficiency of the light quantum. Besides, different exposed facets of {010} in BiOBr(CMC) and {001} in BiOBr resulted in distinct oxygen vacancy structures. O(2)(2-)could be generated via a two-electron transfer pathway on the {010} dominant facets surface in AABR-CMC, leading to the change in photolysis pathway and facilitating more OH produced by AABR-CMC. Compared with pure AgIO3 and BiOBr or BiOBr(CMC), the photocatalytic efficiency of the composites was improved significantly. Optimal photodegradation efficiency for HCHO was achieved for AABR-75 and AABR-CMC50.

NiO/Fe2O3 modified glass carbon (GCE) electrode was prepared by electrodeposition of NiO nanoparticles on Fe2O3/GCE. The electrochemical characteristics of NiO/Fe2O3/GCE have been examined using cyclic voltammetry. The enhanced electrocatalytic activity of NiO/Fe2O3/GCE modified electrode for nitrite oxidation may be related to the synergistic effect of NiO and Fe2O3 nanoparticles, which may not only modify the electronic structure of the composite materials but also favor the increase of active sites in NiO/Fe2O3 and help to adsorb more active materials. To detect nitrite, the NiO/Fe2O3/GCE modified electrode was employed as an electrochemical sensor. There is a strong linear correlation between concentration and peak current (R = 0.9993) in the 5-500 & mu;M range, and a detection limit of 0.05 & mu;M (S/N = 3) was established. NiO/Fe2O3 sensors have excellent selectivity and stability as well. The sensor performs well analytically in determining nitrite in tap water, indicating that it has the possibility for efficient application in nitrite detection. This simple, low-cost, stable and highly sensitive nitrite electrochemical sensor provides a promising method for the detection of nitrite in practical samples.

BiPO4 nanoparticles were loaded into BiOClxBr1-x with hierarchical flower-like structures by hydrothermal method, and an energy band-adjusted BiPO4/BiOClxBr1-x p-n heterojunction with high photoelectrochemical properties was synthesized. Comparing BiPO4 and BiOClxBr1-x to BiPO4/BiOClxBr1-x, improved photoelectrochemical properties are obtained on BiPO4/BiOClxBr1-x. The high performance of BiPO4/BiOClxBr1-x may be attributed to the formation of p-n junction between BiOClxBr1-x and BiPO4, efficiently enhancing charge separation and lowering the recombination rate of photogenerated carriers. The PEC sensor was optimized by adjusting the Cl/Br molar ratio of BiPO4/BiOClxBr1-x. The optimal coupling of the oxidation efficiency and light absorption capacity in various band structures is what causes the 5% BiPO4/BiOCl0.75Br0.25 p-n heterojunction to exhibit the maximum photoelectrochemical activity. The PEC sensor of 5% BiPO4/BiOCl0.75Br0.25 p-n heterojunction presents the low detection limit of 0.11 nM (S/N=3), and it also exhibits high linear ranges (R2=0.9927) of 2-20 μM with good selectivity and stability for the 4-CP detection.

Ternary heterojunction photocatalyst Ag/AgIO3/BiOCl and Ag/AgIO3/BiOCl(CMC) were prepared to solve the contaminants of TC antibiotics residue in water and volatilizing HCHO in indoor air. Morphology modification, heterojunction construction, dominant facet controlling and surface plasma resonance strategies were merged into to modify the photocatalyst. First, biomass solvent assisted synthesis of AABC-CMC does a favor for harvesting the visible light and improving the adsorption of organic pollutants compared to AABC. In addition, Ag nanoparticles (NPs) have been successfully anchored on the surface of heterostructure to enhance the adsorption of visible light, and act as a visible light "trigger" for two wide band gap components of heterojunction. Non-centrosymmetric AgIO3 and band gap matching in heterostructure accelerates separating and transferring of electron-hole pairs, and reduces the probability of recombination. Besides, the IEF differing in BiOCl(CMC) and BiOCl results the difference of photocarriers migrating path when composited with AgIO3.The shorter transmission distance in the AABC-CMC reduces the recombination of photocarriers in the bulk and improve photocatalytic property of AABC-CMC. The possible charge transfer mechanism and key radicals differs in photodegradating process, O2− and OH plays a major role in photo-degrading TC and HCHO, respectively.

BiOCl/diatomite composite with enhanced photocatalytic property for the degradation of liquid Tetracycline hydrochloride (TC) and gaseous formaldehyde (HCHO) were successfully prepared by a facile hydrothermal method at different pH value. The structure and morphology characterizations of BiOCl/diatomite composite exhibit that diatomite not only acts as a natural porous support of photocatalyst but also acts as dominant facets regulator at pH = 3 when the doping amount is change, owing to the surface electrical property of the diatomite and interaction between diatomite and BiOCl. This interaction is certified by XPS and FT-IR which indicate that Bi in layer structure of [Bi2O2](2+) group interacts with the O in Si-O-Si bond when the formation of BiOCl with the participation of diatomite. The BET characterization confirms that the increasing amount of diatomite enables the composite with more reaction points for light harvest and molecule adsorption than pure BiOCl. Furthermore, TC and formaldehyde are targeted as degradation objects to test the photocatalytic property of BiOCl/diatomite composite. The optimum photocatalytic property are BiOCl(3-1.2) and BiOCl(12-0.6) at TC degradation and BiOCl (3-0.3) and BiOCl(12-0.6) at formaldehyde elimination, which is much better than that of pure diatomite or BiOCl. The difference of optimum photocatalysts in liquid and gaseous phase systems can be attributed to the photoelectric performances of BiOCl/diatomite composite, which were characterized by DRS, PL, transient photocurrents and the electrochemical impedance spectroscopy technique. (C) 2019 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved.

The g-C3N4-BiOBrxI1-x nanocomposites were successfully prepared using solvothermal methods. The obtained g-C3N4-BiOBrxI1-x composites had tunable band structures and displayed preferable photocatalytic performance for CO2 reduction irradiated by visible light. Moreover, comparing to pure g-C3N4 and corresponding BiOBrxI1-x, all the obtained g-C3N4-BiOBrxI1-x nanocomposites exhibited distinctly higher activity for CO2 reduction, with 5% g-C3N4-BiOBr0.25I0.75 nanocomposites displaying the best photocatalytic performance. Enhanced photocatalytic performance of g-C3N4-BiOBrxI1-x nanocomposites may arrive from their advantages of high efficiency of electron-hole separation, tunable band structures, and rapid charge transfer. Moreover, a possible visible light induced photocatalytic mechanism on g-C3N4-BiOBrxI1-x nanocomposites was further proposed.

BiIO4 nanoflakes were successfully prepared through a facile hydrothermal method. The as-prepared BiIO4 was characterized by scanning electron microscope (SEM), high-resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD), energy-dispersive spectroscopy (EDS) and ultraviolet visible diffuse reflectance spectroscopy. BiIO4 nanoflakes showed excellent photocatalytic activity for the degradation of phenol solution under simulated solar irradiation. The influence of synthesis temperature on the morphology, size and photocatalytic performance of BiIO4 was investigated. BiIO4 prepared under 140 degrees C exhibited the highest removal rate of phenol under simulated solar light irradiation. In addition, the parametric studies such as the effect of catalyst loading and phenol solution pH were carried out to optimize the reaction conditions. The active species trapping experiment demonstrated that h(+) and center dot OH are the major active species during the photocatalytic process.

AgIO₃/Ag₂O/Ag nanocomposites with enhanced photocatalytic activities were synthesized by a onestep coprecipitation method at room temperature. The optimum hybrid of AgIO₃/Ag₂O = 1.25:1 with Ag nanoparticles (Ag NPs) loading (denoted as AA125) exhibited superior photocatalytic activity, demonstrating 97.19% tetracycline (TC) degradation within 60 min under simulated solar irradiation. This was approximately 10.44 and 2.63 times higher than that of pure Ag₂O and AgIO₃, respectively. The advanced photocatalytic activity can be ascribed to the synergetic effects of the heterostructured AgIO₃/Ag₂O/Ag and the strong surface plasmon resonance (SPR) effect of Ag NPs generated on the surface, which improved the separation and transfer efficiency of photoinduced electron-hole pairs. The results from radical scavenger experiments indicated that the degradation of TC was driven mainly by the participation of superoxide radical (·O-₂).

Constructing heterojunction is an effective way to enhance the catalytic activities of semiconductor photocatalyst owing to its special synergistic effect. In this study, a novel p-n heterostructured CdWO₄/BiOCl nanocomposites were synthesized by a facile hydrothermal and subsequently chemistry bath method. The photocatalytic performance of CdWO₄/BiOCl heterojunctions was investigated by degrading phenol and RhB under simulated solar light irradiation. Highly improved photocatalytic activities were achieved on all CdWO₄/BiOCl heterojunctions compared with both pure CdWO₄ and BiOCl. The CdWO₄/BiOCl heterojunction with optimal mole ratio of 25% CdWO₄ displayed the highest photoactivity with RhB and phenol being completely degraded in 15 min and 6 h, respectively. Mechanism analysis revealed that the interface of p-n heterojunction of CdWO₄/BiOCl composites can produce spontaneously electric field which can effectively separate photogenerated electrons and holes. Moreover, the active species research demonstrated that holes and superoxide radicals proved to be the principal active species during the photocatalytic process. This work demonstrated that the CdWO₄/BiOCl photocatalyst may be a promising material for purifying the organic contaminant in practical application.

A series of novel BiPO4–BiOBrxI1 x p–n heterojunctions were successfully prepared by a facile solvothermal method. The morphology, structure and optical properties of photocatalysts were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and ultraviolet visible diffuse reflectance spectroscopy. The visible light photocatalytic activities of BiPO4–BiOBrxI1 x heterojunctions were investigated by photocatalytically reducing CO2. After 4 hours of irradiation, the 5% BiPO4–BiOBr0.75I0.25 heterojunction showed the highest photocatalytic activity with the yields of CO and CH4 up to 24.9 and 9.4 mmol gcat 1 respectively. The improved photocatalytic activity may be due to the formation of BiPO4–BiOBrxI1 x p–n heterojunctions which can effectively restrict the recombination rate of the photoexcited charge carriers. Moreover, the energy band structure of BiPO4–BiOBrxI1 x heterojunctions could be easily adjusted by changing the mole ratio of I and Br. The possible mechanism of the enhancement of the photocatalytic performance was also proposed based on experimental and theoretical analysis. The present study may provide a rational strategy to design highly efficient heterojunctions with an adjustable energy band for environmental treatment and energy conversion.

3D hierarchical structure BiOX(X ═ Cl, Br)-(CMC) assembled from 2D nanosheets with {010} facets exposed have been successfully synthesized by the assistance of biomass solvent CMC-Na. All the nitrogen adsorption isotherms and photoelectrochemical results reflected that BiOX(X Cl, Br)-(CMC) exhibit higher specific surface area, superior optical absorption efficiency and separation efficiency of photoinduced electron-hole than BiOX(X═Cl, Br) 2D nanosheets exposed with {001} facets. Besides, 96.5% and 60.3% of tetracycline hydrochloride (TC) were photodegradated in 60 minutes under the visible light irradiation catalyzed by BiOBr-(CMC) and BiOCl-(CMC), which is much better than BiOBr and BiOCl. The formation and enhanced photocatalytic activity of 3D hierarchical structure BiOX-(CMC) may be ascribe to the bi-functional groups of CMC, which can affect the crystallization process and morphology of BiOX. According to the merit of environmental friendly and improved photocatalytic activity of the 3D hierarchitecture, we believe that this work broadens the possibility of designing efficient BiOX photocatalyst with {010} facets exposed.

A series of novel BiPO4-BiOBr x I1-x p-n heterojunctions were successfully prepared by a facile solvothermal method. The morphology, structure and optical properties of photocatalysts were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and ultraviolet visible diffuse reflectance spectroscopy. The visible light photocatalytic activities of BiPO4-BiOBr x I1-x heterojunctions were investigated by photocatalytically reducing CO2. After 4 hours of irradiation, the 5% BiPO4-BiOBr0.75I0.25 heterojunction showed the highest photocatalytic activity with the yields of CO and CH4 up to 24.9 and 9.4 μmol gcat -1 respectively. The improved photocatalytic activity may be due to the formation of BiPO4-BiOBr x I1-x p-n heterojunctions which can effectively restrict the recombination rate of the photoexcited charge carriers. Moreover, the energy band structure of BiPO4-BiOBr x I1-x heterojunctions could be easily adjusted by changing the mole ratio of I and Br. The possible mechanism of the enhancement of the photocatalytic performance was also proposed based on experimental and theoretical analysis. The present study may provide a rational strategy to design highly efficient heterojunctions with an adjustable energy band for environmental treatment and energy conversion.

A novel BiIO 4 /Ag 3 PO 4 nanocomposite photocatalyst was synthesized through hydrothermal and chemical precipitation methods. The as-prepared samples were characterized by scanning electron microscope (SEM), X-ray diffraction (XRD), and ultraviolet visible diffuse reflectance spectroscopy. Moreover, the photocatalytic activity was evaluated by degradation of phenol under visible light irradiation. BiIO 4 /Ag 3 PO 4 nanocomposite exhibited higher photocatalytic activity than BiIO 4 and Ag 3 PO 4 , with 5% BiIO 4 /Ag 3 PO 4 nanocomposite displaying the highest activity. The enhanced photocatalytic performance may be due to the formation of BiIO 4 /Ag 3 PO 4 heterojunction interface, which is beneficial to the separation and migration of the photogenerated electrons and holes. In addition, the active species trapping experiment demonstrated that •O 2− and •OH were the major active species during the photocatalytic process.

A novel ferric oxide/multi-walled carbon nanotubes ( $$\hbox {Fe}_{2}\hbox {O}_{3}$$ /MWCNTs)-modified glassy carbon electrode (GCE) was prepared by drop casting $$\hbox {Fe}_{2}\hbox {O}_{3}$$ /MWCNTs onto the surface of GCE. Scanning electron microscopy (SEM) image shows that the $$\hbox {Fe}_{2}\hbox {O}_{3}$$ /MWCNTs has a nanostructure. Cyclic voltammetry (CV) results show that the $$\hbox {Fe}_{2}\hbox {O}_{3}$$ /MWCNTs-modified GCE presents excellent electrochemical activity in the presence of 1 mM nitrite in a 0.1 M phosphate-buffered saline (PBS) to compare the $$\hbox {Fe}_{2}\hbox {O}_{3}$$ and MWCNTs-modified GCE. Differential pulse voltammetry (DPV) results also show that the $$\hbox {Fe}_{2}\hbox {O}_{3}$$ /MWCNTs has excellent electrocatalytic performance to nitrite in a pH 7.0 PBS. The amperometric response result shows that the $$\hbox {Fe}_{2}\hbox {O}_{3}$$ /MWCNTs-modified GCE can be used to detect nitrite concentration in a wide linear range of $$10\textendash 1000\, \upmu \hbox {M}$$ with a detection limit of $$0.1\, \upmu \hbox {M}$$ .

Novel perylene liquid crystals with 2, 4 and 6 peripheral alkyl chains or 6, 8 and 10 peripheral alkyl chains at both the imide and bay-positions were investigated.

Herein, a novel visible-light-driven heterojunction AgI/WO3 nanocomposite was successfully prepared using a facile two-step hydrothermal-precipitation process and applied for photodegradation of organic pollutants. The information of phase structures, morphology, optical properties of the asprepared samples was analysed in detail by XRD, TEM, EDS, STEM, DRS measurement and so on. Formation of the heterostructure and intimate interactions between AgI and WO3 can promote highly effective photogenerated electron-hole pairs separation, which enable the heterojuctions to perform excellent photocatalytic activity as greatly enhanced photocatalysts compared to that of pristine AgI and WO3 for decomposing Rhodamine B (RhB) dye under visible light irradiation. In addition, the AgI/WO3 (1:1) nanocomposites exhibit optimal photocatalytic activity. Moreover, the as-prepared samples exhibit good stability, which is favorable for its potential application. Additionally, we have an analysis on a possible photocatalytic mechanism based on trapping experiments together with other experimental results.