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Constructing a highly efficient and stable photocatalyst is a promising strategy to protect the environment. In this work, we creatively synthesized a novel CdS/Bi4NbO8Cl heterostructured photocatalyst by in situ hydrothermal method. By using ciprofloxacin as target antibiotic residue pollutant, it is found that the CdS/Bi4NbO8Cl shows improved photocatalytic efficiency compared to bare CdS or Bi4NbO8Cl, and the photocatalytic activity of CdS/Bi4NbO8Cl with the molar ratio of 0.3 is the highest, reaching about 90%. X-ray diffraction, scanning electron microscope, and transmission electron microscope were employed to study the composition, morphology, and structure of the composite photocatalysts, while UV–vis diffuse reflection (UV–vis DRS), photoluminescence, transient photocurrent response, electrochemical impedance spectroscopy, and Mott–Schottky plots together show that the significant improvement in photocatalytic activity is due to synergistic effects of enhanced light harvesting and separation of photo-induced charges carriers, caused by the intimate contact between CdS and Bi4NbO8Cl. It is expected that the facile, low-cost method and the excellent performance of the synthesized photocatalyst in this paper can contribute to the management of water pollution.

This paper proposes a network anomaly detection model of direct batch growing hierarchical self-organizing mapping based on entropy, which facilitates clear topology representation for the asymmetrically-distributed data. Since the entropy-defined parameters dynamically vary with the incident dataset, that is, follow a data-adaptive manner, the proposed model is naturally valid in all cases with various data types. For fine-grained data distinguishing, a resemble entropy parameter is proposed for the first time to our best knowledge. The experimental results validate that the proposed model achieves a more efficient network anomaly detection than the conventional models, especially for real-world applications with unexpected anomaly data updating.

Since the photocatalytic effect of a single conventional photocatalyst is often not ideal, it is particularly important to design and construct an efficient and stable photocatalyst in a compound way. In this study, we exploited the sol–gel method to combine BiOCl and TiO2 and gave full play to their respective advantages to prepare BiOCl/TiO2 composite materials. Then, X-ray diffraction (XRD), scanning electron microscope (SEM), and transmission electron microscope (TEM) characterization techniques were utilized to study important indicators of composites—composition, morphology, and structure. In the photodegradation experiment of methyl orange (MO), it was found that the photocatalytic performance of 10BTO (the molar ratio of TiO2 to BiOCl is 10:1) was the best among all the composite photocatalysts, and almost complete degradation of MO was realized. Besides, repeated experiments and recyclability tests on composite materials display favorable stability. Through ultraviolet–visible diffuse reflectance spectroscopy (UV–Vis DRS), photoluminescence (PL), transient photocurrent response, electrochemical impedance spectroscopy (EIS), and electron spin resonance (ESR), a possible degradation mechanism is proposed. Given that there are serious environmental pollution problems in our country, we sincerely hope this research will do its best to degrade organic pollutants in wastewater.

NiTiO3/Bi4NbO8Cl heterostructure photocatalysts were successfully synthesized by a mechanical mixing method. The crystal structure, morphology, optical properties and energy band structures of all samples were determined by X-ray powder diffraction, X-ray photoelectron spectroscopy, scanning electron microscope, transmission electron microscope, ultraviolet–visible diffuse reflection spectra (UV–Vis DRS), and Mott–Schottky tests. The NiTiO3/Bi4NbO8Cl composites were observed to possess an improved activity in the photocatalytic degradation of organic dye rhodamine B (RhB) under irradiation. In particular, Bi4NbO8Cl modified with NiTiO3 (10% in weight) exhibits the best photocatalytic performance. The enhanced photocatalytic performance can be ascribed to the formation of intimate interfacial contact and type-II band alignment between NiTiO3 and Bi4NbO8Cl. From the results of photoluminescence spectra (PL), time-resolved decay spectra (TR-PL), photocurrent and electrochemical impedance spectroscopy, the rapid separation and transportation of photoinduced charge carriers were proved. In addition, the proposed mechanism for the enhanced photocatalytic activities is proposed in this paper.

A new evaluation mechanism was proposed to enhance the representation of data topology in the directed batch growth hierarchical self-organizing mapping. In the proposed mechanism, the growth threshold and the correlation worked in a case-sensitive manner through the statistic calculation of the input data. Since the proposed model enabled a more thorough representation of data topology from both the horizontal and the vertical directions, it naturally held great potential in detecting various traffic attacks. Numerical experiments of network intrusion detection were carried out on the datasets of KDD99, Moore and CICIDS2017, where the good performance validated the superiority of the proposed method.

A strong interfacial contact of heterostructured photocatalysts plays a key role in charges migration, thus promoting photocatalytic performance. Benefiting from the unique two-dimensional (2D) morphology and abundant terminals, 2D/2D “face-to-face” WO3·H2O/g-C3N4 heterostructured self-assemblies were fabricated employing tungsten oxide hydrate (WO3·H2O) nanoplates and graphitic carbon nitride (g-C3N4) sheets as precursors. Compared to pristine WO3·H2O and g-C3N4, the binary WO3·H2O/g-C3N4 heterostructures exhibit excellent photocatalytic performance towards water decontamination, using organic dye rhodamine B/methyl orange as probes. It is found that WO3·H2O/g-C3N4 with 20 wt% mass ratio (WHC-20) possesses the best photocatalytic activities, with about 3.05 times higher than that of pristine g-C3N4. The remarkable increase performance is attributed to the enhanced evolution of superoxide radicals (·O2−) via photoreduction in adsorbed oxygen molecules (O2−), which are promoted by efficient Z-scheme charges separation and rapid electrons transfer at 2D/2D interface. Given the low-cost, facile synthetic procedure and recycling stability, the heterostructured WO3·H2O/g-C3N4 could be served as a promising photocatalyst to deal with water contamination.

Utilizing more solar energy and suppressing recombination of photo-induced charges are primary issues for photocatalyst's design. In this work, BiOBr was introduced into CdTe/TiO2 to construct a novel ternary BiOBr/CdTe/TiO2 composite via a facile solvothermal method. The composition, morphologies, optical properties, specific area, and photocatalytic performances were all investigated in detail. The heterojunction among three-dimensional TiO2 particles, BiOBr and CdTe acts an interfacial channel to boost the charges migration. As a result, the ternary BiOBr/CdTe/TiO2 heterojunctions exhibited higher visible light photocatalytic activities on photo-decolorization of methyl orange (MO) than the pure TiO2 and the binary CdTe/TiO2 and BiOBr/TiO2. Furthermore, the ternary BiOBr/CdTe/TiO2 composites were converted into hollow structure, and showed the better photocatalytic performance, reaching 75% degradation towards MO in 120 min. This study provided an attractive thought to design highly efficient photocatalysts, which possessed a promising for wastewater purification.

Hollow and heterostructured architectures are recognized as an effective approach to improve photocatalytic performance. In this work, ternary TiO2/CdTe/BiOI with hollow structure was constructed via a step-by-step method. In addition, the effect of TiO2 structural regulation and the energy band alignment of BiOI and CdTe quantum dots (CdTe QDs) with TiO2 in TiO2/CdTe/BiOI on photocatalytic dye removal were also studied. The results reveal that the TiO2/CdTe/BiOI heterostructures with hollow substrates exhibit much higher photocatalytic activities than pure TiO2, P25, TiO2/CdTe, and TiO2/BiOI and ternary TiO2/CdTe/BiOI with solid substrates. For TiO2(H)/CdTe/BiOI, several synergistic factors may be responsible for the remarkable visible-light photodegradation performance, such as strong visible-light absorption by BiOI and larger specific surface area.

As an artificial neural network method, self-organizing mapping facilities efficient complete and visualize high-dimensional data topology representation, valid in a number of applications such as network intrusion detection. However, there remains a challenge to accurately depict the topology of network traffic data with unbalanced distribution, which deteriorates the performance of e.g. DoS attack detection. Hence, we propose a new model of the “statistic-enhanced directed batch growth self-organizing mapping”, renew the definition of the growth threshold used to evaluate/control neuron expansion, and first introduce the inner distribution factor for fine-grained data distinguishing. The numerical experiments based on two datasets, KDD99, and CICIDS2017, demonstrate that the key performance in DoS attack detection including the detection rate, the false positive rate, and the training time are greatly enhanced thanks to the statistic concepts consulted in the proposed model.

Constructing heterojunction is an effective strategy to enhance photocatalytic performance of photocatalysts. Herein, we fabricated ZnTiO3/Bi4NbO8Cl heterojunction with improved performance via a typical mechanical mixing method. The rhodamine (RhB) degradation rate over heterojunction is higher than that of individual ZnTiO3 or Bi4NbO8Cl under Xenon-arc lamp irradiation. Combining ZnTiO3 with Bi4NbO8Cl can inhibit the recombination of photo-excited carriers. The improved quantum efficiency was demonstrated by transient-photocurrent responses (PC), electrochemical impedance spectroscopy (EIS), photoluminescence (PL) spectra, and time-resolved PL (TRPL) spectra. This research may be valuable for photocatalysts in the industrial application.

BiVO4/TiO2 nanocomposites were fabricated by a facile wet-chemical process, followed by the synthesis of TiO2 hierarchical spheres via hydrothermal method. The BiVO4/TiO2 nanocomposites were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, UV–Vis diffuse reflectance spectroscopy and X-ray photoelectron spectroscopy. The results showed that prepared TiO2 presented hierarchical spherical morphology self-assembled by nanoparticles and an anatase–brookite mixed crystal phase. The introduction of monoclinic BiVO4 components retained the hierarchical structures and expanded the light response to around 510 nm. Type II BiVO4/TiO2 heterostructured nanocomposites exhibited improved photocatalytic degradation towards methylene blue under visible-light irradiation, especially for the composite photocatalysts with atomic Ti/Bi = 10, which showed double degradation rate than that of pure BiVO4. The enhanced photocatalytic mechanism of the heterostructured BiVO4/TiO2 nanocomposites was discussed as well.

The development of a photocatalyst with high activity, large specific surface area and precise band gap adjustment is the focus of the field of photocatalysis in realizing energy conversion and improving environmental issues. In this paper, a simple synthesis process for co-doping of KCl and NH4Cl to precisely adjust the band gap of g-C3N4 was developed. Various characterization results show that doping with KCl and NH4Cl can reduce the band gap of the carbon nitride, increase its visible light absorption, improve its carrier separation efficiency, thus showing good photocatalytic activity. Cl and K enter the g-C3N4 layers via intercalation and form a dual-element charge transport channel between these layers, thereby facilitating the transport of electrons. The introduction of NH4Cl increases the specific surface area of the composite, thus providing abundant adsorption and reaction sites. The co-loaded photocatalyst CN-NH4Cl-0.05KCl was used to degrade rhodamine B (RhB) and tetracycline (TC) and showed excellent photocatalytic activity. A possible mechanism of photocatalytic degradation is proposed based on the analytic results.

In this study, TiO2 photoanodes doped with samarium ions via a method of hydrothermal treatment were used to fabricate dye-sensitized solar cells (DSSCs). Different doping concentrations were investigated on the effects of the cell’s performance. Some techniques including XRD, scanning electron microscopy, HRTEM, XPS, UV-Vis, photoluminescence were used to characterize the morphology, structure, and optic properties of the prepared photoanodes. The photovoltaic performance of the fabricated cells was further evaluated by measuring the current density–voltage (J–V) curves. It was found that: (1) The down-conversion luminescence effect derived from samarium doping could enhance the light-harvesting ability. (2) Compared with the undoped sample, the samarium-doped cells exhibited enhanced photovoltaic performance. Among the cells with different doping concentrations, the cell TiO2:0.015 Sm showed the best power conversion efficiency of 6.08% with a high open-circuit voltage (Voc) and a short-circuit current density (Jsc).

In this paper, TiO2 particles (~30 nm) modified with Gd2O3-coating layer (~2 nm) for dye-sensitized solar cells (DSSCs) were fabricated via the hydrothermal method. Among the solar cells based on the Gd3+-doped TiO2 photoanodes, the optimal conversion efficiency was obtained from the 0.025Gd3+-modified TiO2-based cell, with a 17.7% improvement in the efficiency as compared to the unmodified one (7.18%). This enhancement was probably due to the improved UV radiation harvesting via a down-conversion luminescence process by Gd3+ ions, enhancement of visible light absorption and improved dye loading capacity. In addition, after Gd modification, a thin coating could be formed on the TiO2 nanoparticles, which worked as an energy barrier and resulted in a lower charge recombination.

TiO2/WO3 composite nanotubes were synthesized in an anodic aluminum oxide (AAO) template by a sol–gel method. The prepared nanotubes were characterized by transmission electron microscopy, scanning electron microscopy, powder X-ray diffraction, and Brunauer–Emmett–Teller surface area. Using the nanotubes embedded in the AAO templates as catalysts, photocatalytic degradation of methyl orange aqueous solution was carried out under UV light irradiation. The results showed that the TiO2/WO3 composite nanotubes with the thickness about 50 nm could be successfully synthesized by this method. TiO2 showed anatase phase and WO3 displayed monoclinic phase. The composite nanotubes (TiO2/WO3) exhibited higher photocatalytic activity than the pure nanotubes (WO3 or TiO2). The possible reason for improving the photocatalytic activity was also discussed.

Heterostructured photocatalysts play a significant role in the removal of contaminants by decreasing the recombination of the photo-induced charges. Herein, we presented novel TiO2/C/BiVO4 ternary hybrids employing a 2D layered Ti3C2 MXene precursor, overcoming the lattice mismatching of TiO2/BiVO4 binary heterostructures simultaneously. Raman and XPS analyses proved the strong coupling effects of TiO2, carbon and BiVO4 components, and the heterostructures were identified from high-resolution transmission electron microscopy results. Moreover, the ternary TiO2/C/BiVO4 composites exhibit excellent photocatalytic performance of Rhodamine B degradation, which is about four times higher than pure BiVO4 and twice that of binary TiO2/BiVO4 heterostructures, reaching a reaction constant of 13.7 × 10-3 min-1 under visible-light irradiation (λ > 420 nm). In addition, for the possible mechanism for dye elimination it was proposed that RhB molecule be directly oxidized by photo-induced holes (h+) on the BiVO4 components and superoxide radical ([Formula: see text]) generated from conduction band electrons of the heterostructures. This work will provide possibilities for developing visible-light responsive nanomaterials for efficient solar utilization.

Highlights: ► New long-lasting CdSiO{sub 3}: Mn{sup 2+}, RE{sup 3+} (RE = Tb, Eu, Nd) phosphors were synthesized by a sol–gel method. ► The afterglow performance of the CdSiO{sub 3}: Mn{sup 2+}, Eu{sup 3+} phosphor was the best. ► The role of RE{sup 3+} co-doped into the CdSiO{sub 3}: Mn{sup 2+} matrix was discussed in this paper. -- Abstract: Mn{sup 2+} and RE{sup 3+} (RE = Tb, Eu, Nd) co-doped CdSiO{sub 3} orange phosphors were prepared at 1050 °C by a sol–gel method. The phase and crystallinity of the synthesized materials were investigated by X-ray powder diffraction (XRD) and scanning electron microscopy (SEM). The luminescence characteristics were analyzed using photoluminescence (PL) spectra, afterglow decay curves, long-lasting phosphorescence spectra, and thermoluminescence (TL) spectra. Due to the difference in co-doped rare earth ionic radii, it varied greatly in trap density and trap depth caused by the different defects deriving from RE{sup 3+} ions co-doping into the CdSiO{sub 3}: Mn{sup 2+} host. The afterglow intensity and time for these samples increased as follows: CdSiO{sub 3}: Mn{sup 2+}0.2%, Nd{sup 3+}0.8% < CdSiO{sub 3}: Mn{sup 2+}0.4%, Tb{sup 3+}0.8% < CdSiO{sub 3}: Mn{sup 2+}0.4%, Eu{sup 3+}0.3%. CdSiO{sub 3}: Mn{sup 2+}0.4%, Eu{sup 3+}0.3% had the best afterglowmore » properties, which could be due to the proper traps formed by Eu{sup 3+} ions co-doping into the host. The role of RE{sup 3+} co-doped into the CdSiO{sub 3}: Mn{sup 2+} matrix and the possible long-lasting phosphorescence process was also discussed in this paper.« less

The ZnNb 2 O 6 powder synthesis was carried out using the molten salt method in the present study. With an inorganic salt mixture of KCl–NaCl as a solvent, the ZnNb 2 O 6 powder could be only obtained at 600 °C while in the cases of temperatures above 600 °C large amount of impurity of NaNbO 3 was present in the products. With the ZnCl 2 addition into the solvent, both the XRD and the SEM examinations showed that the NaNbO 3 could be successfully prevented from formation in a wide temperature range of 600–800 °C and pure ZnNb 2 O 6 were obtained. Besides, the formed ZnNb 2 O 6 rods were noticeably larger with ZnCl 2 present.