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In this work, modified g-C3N4 was fabricated successfully by calcination of ionic liquid (IL) and urea. The addition of IL changed the polymerization mode of urea, induced the self-assembly of urea molecules, modified the morphological structure of the tightly packed g-C3N4, and extended the electron conjugation system. When using 1-butyl-3-methylimidazolium chloride ([Bmim]Cl) as a modifier, the heteroatom Cl could be inserted into the g-C3N4 to optimize the electronic structure. The results of characterizations indicate that the unique structure of modified g-C3N4 has an expanded electron delocalization range, introduces an interlayer charge transmission channel, promotes the charge transmission, reduces the band gap, enhances the absorption of visible light, and inhibits electron-hole recombination. Modified g-C3N4 showed excellent photocatalytic performance for the degradation of rhodamine B and tetracycline. Furthermore, the effect of different anions in 1-butyl-3-methylimidazolium salts ([Bmim]Cl, [Bmim]Br, [Bmim][BF4], and [Bmim][PF6]) on the structure and function of g-C3N4 are discussed.

Recently, solar cells based on inorganic cesium lead triiodide perovskite materials have received considerable attention. However, the quality and thickness of perovskite films are still out from satisfaction due to the limited solubility of the precursor materials. Here, a simple twice-coating process is reported for fabrication of high-quality perovskite films in a complete air condition. Defects such as pinholes, can be effectively eliminated by the second coating with further growth of the grain sizes, thus greatly suppressing charge recombination in these perovskite films. Furthermore, the improved film thickness can ameliorate the absorption of incident light. In consequence, the power conversion efficiency of 11.05% with comprehensively improved device parameters is obtained in traditional inverted planar perovskite solar cells, with a dramatic increase of 42% being compared with the control device (7.83%). In addition, the device's stability is also improved due to such high quality twice-coated perovskite films. The results reveal that such twice-coating technique is a promising choice for high-stablilty and efficient perovskite solar cells.

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.

A new three-dimensional exact solution for the free vibrations of arbitrary thick functionally graded annular sector plates with arbitrary boundary conditions is presented. The three-dimensional elasticity theory is employed to formulate the theoretical model. According to a power law distribution of the volume of the constituents, the material properties change continuously through the thickness of the functionally graded annular sector plates. Each of displacements of the annular sector plates, regardless of boundary conditions, is expanded as a three-dimensional (3-D) Fourier cosine series supplemented with closed-form auxiliary functions introduced to eliminate all the relevant discontinuities with the displacements and its derivatives at the edges. Since the displacement fields are constructed adequately smooth throughout the entire solution domain, an exact solution is obtained based on the Ritz procedure by the energy functions of plate. The excellent accuracy and reliability of the current solutions are demonstrated by numerical examples and comparison of the present results with those available in the literature, and numerous new results for thick FG annular sector plates with elastic boundary conditions are presented. The effects of gradient indexes are also illustrated.

A series of novel binary TiO2/BiOX (X = Cl, Br, I) and ternary TiO2/CQDs/BiOBr hybrid photocatalysts were prepared through a facile hydrothermal method. TiO2/BiOX heterostructures were fabricated by varying the halogen ions. The photocatalysts were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, UV–Vis diffuse reflectance spectroscopy, and X-ray photoelectron spectroscopy. Among the binary TiO2/BiOX, TiO2/BiOBr showed the most preferable photocatalytic activities due to suitable band gap alignment and photo stability, reaching almost 80% MO degradation during 180 min irradiation under simulated sunlight. Moreover, the effects of synthesis temperature, Ti/Bi ratio on the composition and structure were investigated, the results indicated TiO2/BiOBr with Bi/Ti = 10% prepared at 120 °C possessed the best photocatalytic performance. Carbon quantum dots were introduced to accelerate electrons transfer at interface or prevent charges recombination on the surface, resulting a much better photocatalytic performance for TiO2/CQDs/BiOBr hybrid photocatalysts.

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.

To resolve online shopping disputes with product return, some insurance companies have developed a new type of insurance called return-freight insurance to compensate consumers’ loss of return-freight fees. Traditional insurance-premium determination (such as support vector machines) has not fully merged all e-commerce factors, such as the product-fit uncertainty of online shopping, that could affect both insurance demand and return quantity. Based on these traits, we develop a profit-maximization model in terms of certain market-reaction parameters, especially product-fit uncertainty, and calculate the optimal pricing strategy, including both the insurance premium and the compensation. Using prospect theory, we explain why online product review could influence insurance applicants’ risk-averse behavior in the e-commerce situation. Then we solve for the reasonable premium and compensation given online product reviews from the insurance company’s perspective and obtain a number of managerial guidelines for using marketing and operational-strategy variables to influence those reaction parameters so as to obtain the maximum benefit from the market. Interestingly, when consumers’ sensitivity to product-fit uncertainty is moderate, an increase in product-fit uncertainty moves insurance premium and compensation in the opposite direction.

Potassium and iodide codoped mesoporous titanium dioxide (TiO2) was synthesized via an improved sol–gel method using F127 and polyvinylpyrrolidone (PVP) as pore-forming agents. Due to the synergistic effect of codoped K and I, the light absorption of the catalyst is enhanced, and the separation efficiency of photogenerated charge is improved. KI doping also increases the specific surface area, improves the adsorption capacity of TiO2 to pollutants, and promotes active site exposure for organic pollutant degradation. The synthesized potassium and iodide codoped titanium dioxide shows excellent photocatalytic activity and stability under simulated sunlight and exhibits perfect acid and alkali resistance.

In this paper, TiO2 photoanodes were doped with yttrium under different doping concentrations via hydrothermal method and further employed to assemble dye-sensitized solar cells (DSSCs). XRD, XPS, SEM, TEM, UV–Vis DRS and PL measurements were carried out to investigate the yttrium doping effects on crystal structure, chemical status, optical properties and dye loading capacity of the photoanodes. The photovoltaic performance of the photoanodes with various yttrium doping concentration was measured by recording the photocurrent-photovoltaic curves, and the result indicated that TiO2:0.006 Y exhibited the best power conversion efficiency with high short circuit current density (Jsc) and open circuit voltage (Voc). This improvement may be due to the enhanced visible light harvesting, increased dye loading capacity and reduced photoelectron recombination. Keywords: Dye sensitized solar cells, TiO2 photoanode, Rare earth doping, Yttrium

Bi4NbO8Cl is a novel bismuth-based catalyst with a 2D sheet structure for photodegradation under visible light irradiation. However, Bi4NbO8Cl semiconductor has low quantum efficiency, as well as the photogenerated electrons (e-) and holes (h+) tend to recombine in a single semiconductor, thereby decreasing their degradation efficiency. Hence, in this work, Bi2O3/Bi4NbO8Cl 0D/2D heterojunctions containing Bi2O3 quantum dots were prepared to enhance the photocatalytic performance, in which e- and h+ were separated and transferred to different semiconductors for oxidation and reduction, respectively. Compared to bare Bi4NbO8Cl, the photocatalytic activity of 0.5 Bi2O3/Bi4NbO8Cl increases by 2.6 times in the degradation of Rhodamine B since the formation of heterojunctions. X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and Fourier transform infrared spectroscopy (FT-IR) has confirmed the formation of heterojunction. The photoluminescence (PL), photocurrent, and electrochemical impedance spectra (EIS) tests indicate that the quantum efficiency has been improved. This research may be valuable for the industrial application of photocatalysts and provide a new idea for designing photocatalysts.

The strategy to improve the photocatalytic performance is still a challenge for the novel Sillen-Aurivillius perovskite type Bi4NbO8Cl. Herein, heterostructured Bi/Bi4NbO8Cl was fabricated via in-situ solvothermal method, without the additional introduction of Bi-sources. Simultaneously, the amount of oxygen vacancies (OVs) were increased, as the [Bi2O2] blocks released in the solvothermal process to serve as precursors for Bi particles. Due to the large work function of Bi, a Schottky barrier formed at the Bi/Bi4NbO8Cl interface, promoting photo-induced charge separation generated in the Bi4NbO8Cl semiconductor, supplying more holes for the organic compounds decomposition, which could be widely applied in water decontamination. Furthermore, the OVs facilitate the consumption of photo-induced electrons by assisting oxygen activation to produce superoxide radicals (·O2−), leaving more holes in the valence band of Bi4NbO8Cl, and thus result in the enhancement of Rhodamine B (RhB) degradation by 1.82 times over Bi/Bi4NbO8Cl photocatalysts. Through the synergistic effect of Bi and OVs, the Bi/Bi4NbO8Cl also exhibits enhanced photocatalytic performance towards various organic water-contaminants, such as methyl orange, acid orange 7, p-nitrophenol and tetracycline hydrochloride.

Altering the semiconductor composition and suitable energy levels to form a cascade structure is a feasible approach to achieve superior photocatalytic activity. In this study, Bi4NbO8Cl was prepared by a ball milling-calcination method. And one-pot hydrothermal process was developed as a new strategy to synthesize ternary Bi4NbO8Cl/BiOCl/Nb2O5 (BBN) composites, where ultrafine Nb2O5 nanoparticles and BiOCl were in-situ grown and loaded on the surface of Bi4NbO8Cl using NbCl5 as raw material. An enhanced photocatalytic performance towards RhB removal by Bi4NbO8Cl/BiOCl/Nb2O5 is assigned to the in-situ formation of intimated interfaces contacts among Bi4NbO8Cl, BiOCl and Nb2O5, and suitable conduction band (CB) alignments in the ternary hybrid. The staggered energy levels inhibit the recombination of photoinduced electron-hole pairs and increase the separation efficiency of charge carriers, subsequently enhances the photocatalytic efficiency.

Bismuth-based semiconductor materials have been considered as potential and green technology to alleviate various organic pollutants in recent years. In this work, we modified the Bi4NbO8Cl semiconductor via developing hetero-structure to overcome the shortcoming of fast recombination of electrons and holes. Bi2S3 quantum dots with Bi4NbO8Cl were successfully in-situ synthesized by the hydrothermal method, which were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and UV–vis diffuse reflectance spectroscopy. The Bi2S3/Bi4NbO8Cl hetero-structure with broad light absorption region and low recombination efficiency was employed to photodegrade the organic pollutants (rhodamine B, Rh-B) under visible-light irradiation. It exhibited an enhanced photocatalytic degradation of Rh-B compared to Bi4NbO8Cl and Bi2S3, due to the in-situ synthesized Bi2S3 quantum dots that could effectively separate the photo-induced electron-hole pairs and suppress their recombination. Besides, the DFT data further explained the interfacial properties of Bi2S3/Bi4NbO8Cl. Thus, this work provides a unique idea in the design of novel photocatalysts, thereby promoting their potential application in industry.

Layered perovskite oxyhalide Bi4NbO8Cl has been reported as a stable photocatalyst for the organic pollutant removal. In this work, Bi4NbO8Cl was synthesized using liquid-combustion approach, and an efficient Ag/Bi4NbO8Cl photocatalyst was prepared via photo-deposition method. Transmission electron microscope (TEM) and X-ray photoelectron spectroscopy (XPS) display that metallic Ag nanoparticles (∼10 nm) are uniformly distributed on the surface of Bi4NbO8Cl. Owing to a shift of the valence and conduction band and band-gap narrowing, demonstrated by UV-vis diffuse reflection spectroscopy (UV-vis DRS) and Mott-Schottky results, the Ag/Bi4NbO8Cl show enhanced photocatalytic degradation of RhB with almost 100% within 3 h. Photogenerated holes (h+) are foremost active specie responsible for the degradation of RhB via the capture agent test. The improvement of photocatalytic performance of 3% Ag/Bi4NbO8Cl could be attributed to the synergetic effect of the surface plasmon resonance and electron sinkers by Ag nanoparticles, strengthening the visible-light absorption ability, as well as promoting the separation efficiency of charge carriers, which are beneficial for enhancing photocatalytic performance. The present work provides a promising insight into the design Bi-based photocatalysts to solve environmental pollution.

Polymer acceptors for organic solar cells have got increased attention and becoming a strong candidate to replace small molecular electron acceptors. Here, a polymer acceptor (PBDTβNPDI) was constructed with naphthyl substituted asymmetric benzo [1,2-b:4,5-b']dithiophene (BDTβN) as donor unit and simple N,N′-Bis(1-propylbutyl)-1,7-dibromoperylene-3,4:9,10-tetracarbox- diimide (PDI) as acceptor unit. The designed polymer has broad absorption spectrum and tuned aggregation with asymmetric donor unit. Then all-polymer solar cells based on PTBTz-2 electron donor and PBDTβNPDI electron acceptor were prepared. The results exhibit that the device has matched energy levels, complementary absorption spectra, and desirable crystallites and nanoscale phase separation, which result in balanced mobility, low weak bimolecular recombination, and thus obtain a remarkable power conversion efficiency of 6.14% with high short circuit current density of 13.89 mA cm−2 and decent open circuit voltage of 0.88 V. The results indicate that rational regulation of PDI polymers by asymmetric strategies can obtain ideal polymer accepters, and it has a strong potential to get better results with our in-depth research.

CdSiO3: Mn2+, Eu3+ long-lasting phosphor was prepared by sol–gel method. The phosphor particles were characterized by the X-ray diffraction (XRD), scanning electron microscopy (SEM) and fluorescence spectrophotometer. The excitation and emission spectra indicated that the particles emitted strong light at 587 nm under around 280 nm excitation. The effects of the calcining temperature and the soaking time on the afterglow properties were studied systematically. Comparing with conventional solid-state synthesis method, the sol–gel method had the advantages such as low energy consumption and homogeneous mixing. In this paper, the decay speed of the afterglow for CdSiO3: Mn2+, Eu3+ particles was slower than that obtained by the conventional solid-state synthesis method. In addition, role of Eu3+ co-doped into CdSiO3: Mn2+ matrix was also discussed in this paper.

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

CdSiO 3 : Mn 2+ , Tb 3+ long-lasting phosphor was prepared by the conventional high temperature solid-state method. Effects of the content of Mn 2+ and Tb 3+ on the luminescent properties of phosphor CdSiO 3 : Mn 2+ , Tb 3+ were investigated by means of photoluminescence (PL) spectra, the afterglow intensity decay curves and the thermoluminescence (TL) spectra. It was found that when the Mn 2+ and Tb 3+ dopant-concentrations were 0.4 mol% and 0.8 mol% of Cd 2+ ions in CdSiO 3 , respectively, the luminescence of phosphor prepared had better luminescent property and longer afterglow time. Role of Tb 3+ co-doped into CdSiO 3 : Mn 2+ matrix was discussed in this paper.

ZnO powders with different Co2+ doping concentrations (0, 0.5, 1, 3 and 5 mol%) were prepared by the hydrothermal method and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), UV–vis diffuse reflectance spectrometer, and photochemical reaction instrument. The results show that the ZnO powders are hexagonal wurtzite structures and their crystallization decrease with the increase of Co2+ doping concentration. The products are spherical which have diameter of about 200 nm, and their absorption edge shift to longer wavelength with the increase of the Co2+ concentration. The photocatalytic activities of the powders are evaluated using a basic organic dye, methyl orange (MO). Compared with undoped ZnO, it is found that the photocatalytic properties of the Co-doped ZnO have been improved greatly. When the doping concentration is 3 mol%, the degradation ratio of MO can reach 78% after reacting for 240 min.

CdSiO 3 : Mn 2+ , RE 3+ (RE = Sm, Dy, Eu) long-lasting phosphors were prepared by the conventional high temperature solid-state method. The results of XRD measurement indicated that the products calcined at 1050 °C for 3 h had a good crystallization without any detectable amount of impurity phase. From photoluminescence (PL) spectra and the afterglow intensity decay curves, rare-earth ions co-doped CdSiO 3 : Mn 2+ phosphors possessed better luminescence properties than Mn 2+ doped ones. Role of Eu 3+ co-doped into CdSiO 3 : Mn 2+ matrix was discussed in this paper.

Pure CdSiO3 powder was successfully prepared by sol–gel method using Cd(NO3)2·4H2O and (CH3CH2O)4Si (TEOS) as raw materials. The prepared powders were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM) respectively. The effects of the reacting temperature and the calcining time on phase formation and size homogeneity were investigated. The results indicated that the single phase CdSiO3 powders with good homogeneity and good crystallization could be obtained by sol–gel method at 900 °C for 2 h.

Polyaniline was deposited potentiodynamically on a stainless steel substrate in the presence of an inorganic acids (sulfuric acid). The electrochemical characterization of the electrode was carried out by means of cyclic voltammetry and electrochemical impedance spectroscopy in the organic acids (p-toluene sulfonic acid) solution. The results show that polyaniline has a high specific capacitance of ∼431.8 F g−1 at 1 mV s−1, high coulombic efficiency of ∼95.6% at 20 mV s−1, and exhibits a high reversibility. This indicates the promising feasibility of the polyaniline used as an electrochemical capacitor material in the electrolyte of p-toluene sulfonic acid solution especially at high charge–discharge process.

The syntheses of Nd2O3 nanowires were performed through sol–gel process assisted with porous anodic aluminum oxide (AAO) as a template. The morphology and the phase composition of the prepared nanowires were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and energy disperse spectroscopy (EDS). The results showed that the Nd2O3 nanowires could be successfully synthesized by using this method. The nanowires had successfully grown into the nanochannels of the AAO template. The prepared nanowires were quite uniform. Both the XRD and EDS examinations revealed that the obtained nanowires were not others but Nd2O3.

CdSiO 3 :Mn 2+ , Dy 3+ long-lasting phosphor was prepared by the conventional high temperature solid-state method. Effects of the content of Mn 2+ and Dy 3+ on the luminescent properties of phosphor CdSiO 3 :Mn 2+ , Dy 3+ were investigated by means of photoluminescence (PL) spectra and the afterglow intensity decay curves. It was found that when the Mn 2+ and Dy 3+ dopant concentrations were 1 and 0.8 mol% of Cd 2+ ions in CdSiO 3 , respectively, the luminescence of phosphor prepared had better luminescent property and longer afterglow time. Role of Dy 3+ co-doped into CdSiO 3 :Mn 2+ matrix was discussed in this paper.

The Bi 0.5 (Na 0.7 K 0.2 Li 0.1 ) 0.5 TiO 3 powder synthesis through molten salt method was investigated in the temperature range of 650–700 °C for 2–4 h. The XRD results indicated that the optimal synthesizing temperature for molten salt method was 700 °C, significantly lower than that for conventional processing route of solid state reaction method, where a calcining temperature of 850 °C was needed. The SEM results revealed better crystallization of the powders obtained through molten salt method, compared with those through the conventional processing route of solid state reaction method.

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.

In this paper, the concept of possibility is further considered, fuzzy optimal value of the linear programming with fuzzy numbers is given, and the continuity theorems of optimal value in parametric linear programming are proposed.