Facile Construction of 2D/2D ZnIn2S4-Based Bifunctional Photocatalysts for H2 Production and Simultaneous Degradation of Rhodamine B and Tetracycline.

A two-dimensional/two-dimensional (2D/2D) TiO2/ZnIn2S4 photocatalyst was reasonably proposed and constructed by a two-step oil bath-hydrothermal method. TiO2 nanosheets uniformly grown on the surface of ZnIn2S4 nanosheets and a synergetic effect between the TiO2 and ZnIn2S4 could highly contribute to improving the specific surface area and hydrophilicity of ZnIn2S4 as well as accelerating the separation and transfer of photon-generated e--h+ pairs, and thus enhancing the visible-light photocatalytic degradation and H2 evolution performance of ZnIn2S4. Rhodamine B (RhB) and tetracycline (TC) were simultaneously selected as the target pollutants for degradation in the work. The optimum photocatalytic RhB and TC degradation properties of TiO2/ZnIn2S4-10 wt% were almost 3.11- and 8.61-fold higher than that of pure ZnIn2S4, separately, while the highest photocatalytic hydrogen evolution rate was also observed in the presence of TiO2/ZnIn2S4-10wt% and 4.28-fold higher than that of ZnIn2S4. Moreover, the possible photocatalytic mechanisms for enhanced visible-light photocatalytic degradation and H2 evolution were investigated and proposed in detail. Our research results open an easy pathway for developing efficient bifunctional photocatalysts.

Coupling ZnIn2S4 Nanosheets with MoS2 Hollow Nanospheres as Visible-Light-Active Bifunctional Photocatalysts for Enhancing H2 Evolution and RhB Degradation.

In this study, Mo-glycerate was used as a precursor to create MoS2 hollow nanospheres (HNS), which were then used for the first time to modify ZnIn2S4 nanosheets to create MoS2 HNS/ZnIn2S4 photocatalysts. The findings demonstrate that MoS2 HNS/ZnIn2S4 heterojunctions exhibited remarkably boosted photocatalytic properties and excellent reusability for both RhB degradation and H2 evolution without the use of Pt as a co-catalyst. Among the heterojunctions, the RhB degradation and H2 evolution efficiencies of the optimized MoS2 HNS/ZnIn2S4-3 wt % composite were almost 5 and 34 times higher than those of ZnIn2S4, respectively. The excellent performance of MoS2 HNS/ZnIn2S4-3 wt % might be attributed to the expansion of the visible-light response range and the accelerated separation efficiency of photo-induced carriers, according to the findings of the optical property tests. Based on the established band gap position and characterization results, a potential mechanism for appealing photocatalytic activity over MoS2 HNS/ZnIn2S4 heterojunctions was also postulated.

Fabrication and enhanced visible-light photocatalytic H2production of B-doped N-deficient g-C3N4/CdS Hybrids with robust 2D/2D hetero-interface interaction.

2D layered photocatalysts with proper electronic structure have sparked much attention in the field of visible-light photocatalysis for H2production. Herein, by simply calcining the mixture of ultrathin g-C3N4(CNN) and NaBH4, heteroatom B and N defect were simultaneously introduced into g-C3N4. The obtained modified g-C3N4(BDCNN) was further coupled with 2D flower-like CdS nanosheet. The optimal 2D/2D BDCNN/CdS-15% heterojunction behaved ideal photocatalytic activity for H2revolution by water splitting, and the highest H2revolution rate was as high as 1013.8µmol g-1h-1, which was 6.7 times, 2 times, and 5.8 times of the corresponding values of pristine CNN, BDCNN and CdS respectively. It was evidenced that the band structure of 2D/2D BDCNN/CdS-15% was well tuned for better visible-light adsorption and higher separation efficiency of photo-induced carriers for enhancing H2revolution performance. The achievement in this study provided informative principles for exploring g-C3N4based heterojunctions with higher H2-production performance.

In situ fabrication of a novel CdS/ZnIn2S4/g-C3N4 ternary heterojunction with enhanced visible-light photocatalytic performance.

In this study, a novel g-C3N4-based ternary heterojunction was rationally designed and constructed by the in situ growth of ZnIn2S4 nanosheets and CdS nanoparticles onto the g-C3N4 nanosheets using a facile two-step oil-bath method. Through optimizing the proportion of ZnIn2S4 and CdS component, g-C3N4 nanosheets coupled with ZnIn2S4 nanosheets and CdS nanoparticles (denoted as CdS/ZnIn2S4/g-C3N4) exhibited obviously higher photocatalytic properties for RhB removal than the single-component and dual-component systems. Among the as-obtained ternary photocatalysts, it was found that the ternary CdS/ZnIn2S4/g-C3N4-0.2 photocatalyst displayed the optimum photocatalytic property (96%) within a short time (30 min), which was almost 27.42 and 1.17 times higher than that of pure g-C3N4 and binary ZnIn2S4/g-C3N4-0.7 composite. The excellent activity of the ternary CdS/ZnIn2S4/g-C3N4 heterostructure is assigned to the synergetic effects of CdS nanoparticles, ZnIn2S4 nanosheets and g-C3N4 nanosheets, which not only broaden the visible-light absorption range, but also improve the charge mobility and separation rate, thus boosting the visible-light-driven photocatalytic property of g-C3N4.

In situself-assembly fabrication of ultrathin sheet-like CuS modified g-C3N4heterojunction and its enhanced visible-light photocatalytic performance.

Photocatalysts with heterojunction structure have been widely used for organic degradation. In this study, CuS/g-C3N4heterojunction was formed byin situself-assembly via a simply hydrothermal method. A series of characterizations were applied to analyzing the morphology, structure, optical properties and photo-induced electron transfer of the samples. The effect of CuS mass ratio in the CuS/g-C3N4composite on methyl blue (10 mg l-1) degradation under visible-light illumination was discussed. When CuS mass ratio was 60%, CuS/g-C3N4behaved the highest photocatalytic efficiency which is 17 times higher than that of pure g-C3N4, and the optimal heterojunction exhibited promising photocatalytic stability as well. The synthesized CuS/g-C3N4with intimate contact and promising photocatalytic performance provides important implications on analogous researches on g-C3N4-based heterojunctions for photocatalytic applications.

Enhanced H2evolution performance by carbonized SiC/g-C3N4heterojunction under visible-light illumination.

In this study, carbonized silicon carbide/graphitic carbon nitride ((SiC/C)/g-C3N4) composites were fabricated via a facile calcination method. The optimal SiC/C/g-C3N4composite shows an excellent visible-light photocatalytic activity for water splitting, with the highest hydrogen evolution amount being 200.2µmol, which is four times higher than that of pure g-C3N4when triethanolamine and platinum (1.0 wt%) are used as the sacrificial agent and cocatalyst, respectively. With an intimate interface between SiC/C and g-C3N4, the energy band structure of g-C3N4was well engineered for photocatalytic H2production. This study provides a novel method for fabricating g-C3N4-based heterojunctions for application in environmental conservation.

Effect of kerosene combustion atmosphere on the mild steel oxide layer.

In arson cases, accelerants were usually used by criminals to achieve the purpose of rapid arson. Therefore, fire investigators aim to determine whether accelerants was used in the fire scene. Metallic material has to react with corrosive gas around it at high temperature and the oxidation products may store the information of reactants. Accelerants present in fire scenes impart some oxidative characteristics on metallic materials. The aim of this work is to figure out the possibility to identify the presence of accelerant in a fire according to the oxidation patterns of metallic material. This paper researched the oxidation behavior of mild steel at high temperature in a simulated flame environment. The surface morphological and cross-sectional microstructural features of the samples were characterized by X-ray diffractions, X-ray photoelectron spectroscopy and scanning electron microscopy with energy-dispersive spectroscopy analysis after oxidation. The carbon in the combustion atmosphere had a carburizing effect on the metal oxide layer. It was mostly C-C, C-O and C=O of organic matter could be used as in fire investigation. Various oxidizing atmosphere composite systems promote the formation of metal oxide layers. And bidirectional oxidation mode in the oxide layer further accelerates the oxidation rate. The (wustite) FeO phase was not found in the oxide layer because of the strong oxidation of the combustion atmosphere. These results offer complementary information in fire characteristics, which combining the characterization of surface scale with traditional chemical analysis of recovering ignitable liquid residues from fire debris are expected to offer crucial information for determining the presence of combustion accelerants at a fire scene.

Construction of 3D CrN@nitrogen-doped carbon nanosheet arrays by reactive magnetron sputtering for the free-standing electrode of supercapacitor.

Owing to their favorable chemical stabilities and electronic conductivities, transition metal nitrides (TMNs) have been targeted as the potential electrode materials for the supercapacitors. Herein, 3D CrN@nitrogen-doped carbon nanosheet arrays (NCs) were successfully deposited on carbon paper (CP) by reactive magnetron sputtering method. The CrN@NCs@CP electrode exhibited satisfactory electrochemical properties: initially, the electrode showed a 132.1 mF cm-2specific capacitance at 1.0 mA cm-2current density; subsequently, the electrode demonstrated a 95.9% capacitance retention after 20 000 galvanostatic charge-discharge cycles at 5.0 mA cm-2current density. The specific capacitance of the CrN@NCs@CP electrode was significantly higher than that of the CrN@CP electrode (4.1 mF cm-2at 1.0 mA cm-2). Furthermore, the symmetric supercapacitor that incorporated two CrN@NCs@CP electrodes demonstrated 5.28µWh cm-2(2.7 Wh kg-1) energy density at 0.41 mW cm-2power density. These findings exemplify the suitability of the 3D composite electrodes of TMNs for energy storage application.

Acid etching followed by hydrothermal preparation of nanosized Bi2O4/Bi2O3 p-n junction as highly efficient visible-light photocatalyst for organic pollutants removal.

As a promising visible-light photocatalyst, Bi2O4 has the advantage of broadband spectral response range. However, the high recombination rate of photoexcited charge carriers induced by the submicrorod morphology of pure Bi2O4 greatly restricts its visible-light photocatalytic performance. Herein, a novel nanosized Bi2O4/Bi2O3 p-n junction was developed by a dilute HCl acid etching and subsequent hydrothermal method, using NaBiO3·2H2O as the sole bismuth precursor. A product of NaBiO3·2H2O@BiOCl was formed firstly when NaBiO3·2H2O was partially reduced by insufficient dilute HCl aqueous solution. Then, BiOCl reacted with NaBiO3·2H2O during the following hydrothermal reaction process, resulting in the formation of Bi2O4 nanoparticles (NPs) anchored on the surface of plate-like Bi2O3. The content of Bi2O3 in the junction can be easily controlled by changing the added amount of dilute HCl acid. This strategy could not only realize the NPs-sized Bi2O4 but also construct nanometered Bi2O4/Bi2O3 p-n junction simultaneously, which remarkably improves the separation efficiency of charge carriers. Furthermore, the obtained Bi2O4/Bi2O3 heterojunctions have larger specific surface areas than Bi2O4 alone. Due to these advantages, the photocatalytic removal rate of methyl orange (MO) and phenol for the optimal Bi2O4/Bi2O3 heterostructure increased respectively by 5.06 and 2.16 times under visible light, when compared with single Bi2O4. The results of active species trapping experiment and electron spin resonance (ESR) spectra indicate that holes (h+) and superoxide radicals (O2-) are the primary and secondary reactive active species during the photocatalytic degradation process, respectively. This work provides a novel perspective for the design and preparation of high performance Bi2O4-based photocatalyst.

Enhanced Visible-Light Photocatalytic Performance of SAPO-5-Based g-C3N4 Composite for Rhodamine B (RhB) Degradation.

Novel visible-light responded aluminosilicophosphate-5 (SAPO-5)/g-C3N4 composite has been easily constructed by thermal polymerization for the mixture of SAPO-5, NH4Cl, and dicyandiamide. The photocatalytic activity of SAPO-5/g-C3N4 is evaluated by degrading RhB (30 mg/L) under visible light illumination (λ > 420 nm). The effects of SAPO-5 incorporation proportion and initial RhB concentration on the photocatalytic performance have been discussed in detail. The optimized SAPO-5/g-C3N4 composite shows promising degradation efficiency which is 40.6% higher than that of pure g-C3N4. The degradation rate improves from 0.007 min-1 to 0.022 min-1, which is a comparable photocatalytic performance compared with other g-C3N4-based heterojunctions for dye degradation. The migration of photo-induced electrons from g-C3N4 to the Al site of SAPO-5 should promote the photo-induced electron-hole pairs separation rate of g-C3N4 efficiently. Furthermore, the redox reactions for RhB degradation occur on the photo-induced holes in the g-C3N4 and Al sites in SAPO-5, respectively. This achievement not only improves the photocatalytic activity of g-C3N4 efficiently, but also broadens the application of SAPOs in the photocatalytic field.

The Optimal Distance of the Electrode to the Lifting Film Surface when Lifting Dust Footwear Impressions Using an Electrostatic Dust Print Lifter.

Footwear impressions are one of the valuable physical evidence encountered at crime scenes and its identification can facilitate narrowing down the suspects and establishing the identity of the criminals. The technique of electrostatic lifting (ESL) dust shoeprints at crime scenes is well established with scenes of crime examiners. And in the procedure, the recovery of the original item containing the impression should be made as good as it can and not damage the marks. In this study, the different particle sizes of SiO2 were used to simulate dust and light soil residues, comparing different particle sizes and electrode positions were used to compare the adsorption ability on the surface of electrostatic lifting film in high-voltage electrostatic field for the collection of shoeprints. The results indicated that lifting film in electrostatic field will be pressed down to the dust surface, the compaction and electrostatic adsorption force will vary with the distance between the high-voltage electrode and film surface. Reducing the distance can increase the electric field strength near the lifting film, and the adsorption capacity of Mylar aluminum-plating film to dusts can be improved significantly. Adsorption capacity of the lifting film was related to the size of dust particles and significantly improved with the increase of the particle charge. The optimum distance which can get the best adsorption capacity between the electrode and film surface is from 10 to 15 mm.

TiO2-graphene composites with exposed {001} facets produced by a one-pot solvothermal approach for high performance photocatalyst.

TiO2-graphene (TOG) composites with exposed TiO2 {001} facets were prepared by a solvothermal approach without any addition of surfactants or capping agents, only using titanium isopropoxide and graphene oxide ethanol suspension as the precursors. Graphene was covered uniformly and densely with anatase TiO2 nanoparticles, exposing the {001} facets. The X-ray photoelectron spectroscopy, photoluminescence spectroscopy and photocurrent measurements show the presence of electron transfer between TiO2 and graphene. The electron transfer between TiO2 and graphene will greatly retard the recombination of photoinduced charge carriers and prolong electron lifetime, which will contribute to the enhancement of photocatalytic performance. Accordingly, the TOG composites show high photocatalytic activity of methyl orange under UV light, likely due to the effective separation of photoinduced charge, exposure of highly reactive {001} facets and great adsorptivity of dyes.

Erosion effects of atomic oxygen on polyhedral oligomeric silsesquioxane-polyimide hybrid films in low earth orbit space environment.

A novel polyimide (PI) hybrid nanocomposite containing polyhedral oligomeric silsesquioxane (POSS) had been prepared by copolymerization of trisilanolphenyl-POSS, 4,4'-oxydianiline (ODA), and pyromellitic dianhydride (PMDA). The AO resistance of these PI/POSS hybrid films was tested in the ground-based AO simulation facility. Exposed and unexposed surfaces were characterized by SEM and X-ray photoelectron spectroscopy. SEM images showed that the surface of the 20 wt% PI/POSS became much less rough than that of the pristine polyimide. Mass measurements of the samples showed that the erosion yield of the PI/POSS (20 wt.%) hybrid film was 1.2 x 10(-25) cm3/atom, and reduced to 4% of the polyimide film. The XPS data indicated that the carbon content of the near-surface region was decreased from 60.1 to 13.2 at% after AO exposure. The oxygen and silicon concentrations in the near-surface region increased to 1.96 after AO exposure. The nanometer-sized structure of POSS, with its large surface area, had led AO-irradiated samples to form a SiO2 passivation layer, which protected the underlying polymer from further AO attack. The incorporation of POSS into the polyimide could dramatically improve the AO resistance of polyimide films in low earth orbit environment.