X-ray Photoelectron Spectrophotometer Research Articles

Impact of Ca2+, Ce3+ codoping on ZnSnO3-SnO2 heterostructure for dielectric, optoelectronic and solar cell applications

We have successfully prepared a new mixed oxide system of Sn-rich ZTO (ZnSn2O5). The impact of coupling Ca2+ and Ce3+ inside the lattice of ZnSn2O5 on the dielectric, optical, and photoelectric conduction properties was investigated. In this regard, the co-precipitation technique was used to prepare three samples of ZTO, Ca-ZTO, and Ca/Ce-ZTO. The samples have been investigated by X-ray diffractometer (XRD), Fourier transform infrared (FTIR), field emission scanning electron microscope (FESEM), X-ray photoelectron spectrophotometer (XPS), and an energy dispersive X-ray spectrometer (EDS). The XRD pattern detected phases that highly interfere as a heterostructured compound. The pristine ZTO particles demonstrate a mixture of two morphologies, hexagonal and quasi-spherical shapes, with particle size distributions of 0.25–1.5 µm, resulting in significant porosity between these particles. Meanwhile, the particles of Ca/Ce-doped ZTO have a homogenous morphology as spherical shape and exhibit larger density, particle size distribution range of 1–2 µm. The dielectric constant as a function of frequency or wavelength is increased with the applied temperature (32 to 140 °C) for both pure and Ca/Ce-ZTO samples. Clearly, Ca/Ce-ZTO displays higher absorption in visible light and the estimated band gaps of ZTO, Ca-ZTO, and Ca/Ce-ZTO are equal to 1.58,1.56 and 1.48 eV, respectively. The pristine ZTO showed a stronger n-type effect than Ca and Ca/Ce-doped ZTO samples. The shift from n-type to being close to N-P junction by multiple doping induces the application of these heterostructured materials as buffering layers in energy conversion applications like thin film solar cells and light emitting diodes.

Effect of annealing time on the structure and conductivity of amorphous polycarbosilane-derived silicon carbide ceramics

The isothermal evolution of free carbon structure and conductivity of polycarbosilane-derived SiC(O) ceramics pyrolyzed at 1100 °C, 1200 °C, and 1300 °C for 3–55 h was systematically investigated using different characterization methods, which include X-ray photoelectron spectrophotometer (XPS), Raman spectroscopy, Electron Paramagnetic Resonance (EPR), and Transmission electron microscope (TEM). At 1100 °C, increasing annealing time led to structural rearrangement of free carbon, anti-growth behavior, higher degree of order, and increasing and then decreasing number of defects. At 1200 °C, a complex structural evolution of free carbon was observed, which followed the sp3-to-sp2 transition and increased the ordering degree. At 1300 °C, increasing annealing time resulted in both lateral growth and increasing ordering of free carbon, which enhanced the carbon cluster size and decreased the number of defects. Enhanced sample conductivity with prolonged annealing time was observed and is discussed based on structural evolution of SiC(O) ceramics at different temperatures.

Multi-ionic interaction with magnesium doped hydroxyapatite-zeolite nanocomposite porous polyacrylonitrile polymer bead in aqueous solution and spiked groundwater

Removal of multi-ionic contaminants from water resources has been a major challenge faced during the treatment of water for drinking and industrial applications. In the present study, varying composition of magnesium doped hydroxyapatite (Mg-HAp) and zeolite nanocomposite embedded porous polymeric beads were synthesized using solvent displacement method and its sorption efficiency towards multi-ion contaminant (such as Ag, Al, As, Ba, Be, Cd, Co, Cr, Cu, Mn, Ni, Pb, Se, Tl, Th, U, V and Zn) was investigated in aqueous solution and spiked groundwater. The prepared beads were characterized using suitable techniques like high-resolution transmission electron microscopy (HRTEM), scanning electron microscopy (SEM), and Brunauer-Emmett-Teller (BET) equation. The surface area and pore radius of the beads varied from 6.996 to 66.469 m2/g and 1.698–3.960 nm respectively according to the composition of the bead. The control bead without nanocomposite showed maximum surface area. Multi-ion adsorptions onto beads were confirmed using an inductively coupled plasma-optical emission spectrophotometer (ICP-OES) and X-ray photoelectron spectrophotometer (XPS). The sorption efficiency was high at pH 5 owing to its anionic surface charge leading to an increase in affinity towards the cations. For validating field application, selected high performance beads were tested in multi-ion spiked groundwater. The results indicated that the Mg-HAp nanocomposite bead dominate all the other bead compositions with more than 90% removal efficiency for most of the multi-ion contaminants. The feasible adsorption mechanism has been discussed. This adsorption study revealed that the Mg-HAp nanocomposite bead is a promising material that is cost-effective, non-toxic, biodegradable, eco-friendly and highly efficient towards the removal of multi-ionic contaminants from groundwater.

Green corrosion inhibitors for drilling operation: New derivatives of fatty acid-based inhibitors in drilling fluids for 1018 carbon steel in CO2-saturated KCl environments

Corrosion of the oilfield drilling equipment can considerably affect its drilling effectiveness, service life, and operation safety as well as the surrounding environment. In this study, inhibition effects of three eco-friendly fatty acid-based inhibitors, Polyethylene glycol-2 oleamide (PEG-2 oleamide), Glycerol myristate (GM) and Glycerol linoleate (GL), in emulsion-based drilling fluids against corrosion of carbon steel were investigated. The inhibitors were characterized by Fourier transform infrared (FT-IR) spectroscopy and CHNS–O analysis. Effects of the inhibitors on corrosion of the steel were evaluated by means of electrochemical measurements of open circuit potential (OCP) and potentiodynamic polarization as well as electrochemical impedance spectroscopy (EIS). Scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and X-ray photoelectron spectrophotometer (XPS) were employed to study morphology and the chemical composition of surface layer adsorbed on the metal surface. The study demonstrates remarkable performance of the green inhibitors especially PEG-2 oleamide, which shows an inhibition efficiency of 99.7%. The high inhibition capability results from a formed protective layer that blocks corrosive ions to attack the steel surface. First-principles calculations and molecular dynamics simulation were performed, which reveal chemical bonding between the inhibitors and iron surface, and stronger intermolecular attraction in the adsorbed film of, e.g., PEG-2 oleamide, which renders the PEG-2 oleamide–induced film particularly durable.

Incorporation of trimetallic nanoparticles to the SiO2 matrix for the removal of methylene blue dye from aqueous medium

The removal of toxic dyes from the wastewater is a serious concern. One of the commonly employed dyes in the textile industry is methylene blue (MB). Its presence in water not only reduces the aesthetic value of the water but also affects aquatic life. Considering this, we have worked on the designing of Bi2O3-SrO-FeO@SiO2 nanocomposite using a simple microwave irradiation method. The synthesized Bi2O3-SrO-FeO@SiO2 nanocomposite was characterized by various techniques such as scanning electron microscope, transmission electron microscope, X-Ray diffractometer, elemental mapping, Energy- dispersive X-Ray, and X-ray photoelectron spectrophotometer. The adsorption technique was utilized for the effective removal of MB using Bi2O3-SrO-FeO@SiO2 nanocomposite. Effects of various factors such as the concentration of MB, amount of Bi2O3-SrO-FeO@SiO2 nanocomposite, and reaction time were undertaken for getting some optimized parameters for the further experiments. Adsorption isotherm models such as Langmuir, Freundlich, and Temkin were employed for the adsorption data. Besides, adsorption kinetic models such as Pseudo- first order and Pseudo- second-order were also studied for determining the rate of the undertaken adsorption process. At last, the reusability of the Bi2O3-SrO-FeO@SiO2 nanocomposite was studied for six consecutive cycles for elaborating the practical application of the synthesized adsorbent.

Effect of binary zinc-magnesium oxides on polyphenylsulfone/cellulose acetate derivatives hollow fiber membranes for the decontamination of arsenic from drinking water

Arsenic contamination is continuously threatening the safety of drinking water in many parts of the world. The consumption of chronic arsenic contaminated drinking water can cause serious health related issues. Therefore, the synthesis of novel materials is very much essential for the selective removal of arsenic from aqueous solution. In the present investigation, the effect of increased concentrations (0.6, 1.0 and 1.5 wt%) of binary zinc-magnesium oxide (ZnO-MgO) on cellulose acetate (CA)/polyphenylsulfone (PPSU) and cellulose acetate phthalate (CAP)/PPSU hollow fiber membranes for arsenic removal was performed. As used ZnO-MgO was characterized by using x-ray diffraction (XRD), transmission electron microscopy (TEM) and particle size distribution. Fabricated hollow fiber membranes were characterized using scanning electron microscopy (SEM), atomic force microscopy (AFM), zeta potential, fourier transform infrared (FTIR), x-ray photoelectron spectrophotometer (XPS), thermogravimetric analysis (TGA) and antifouling studies. The results revealed that, there is significant enhancement in the overall performance of the ZnO-MgO containedmembranes. An enhancement of arsenic removal properties was demonstrated from 0.6 wt% of ZnO-MgO in CAP/PPSU (ZMCAP-0.6) membrane was 81.31% with the retention permeability of 69.58 L/m2h bar respectively. Similarly, 1 wt% of ZnO-MgO in CA/PPSU (ZMCA-1) was found to be 78.48% and 198.47 L/m2h bar respectively using 1 ppm laboratory prepared aqueous arsenic solution (pH 6.8 ± 0.2) at 1 bar transmembrane pressure. In addition, improved antifouling properties was noticed with an increased flux recovery ratio and enhanced thermal stability from ZnO-MgO contained membranes. Therefore, as fabricated ZnO-MgO contained membranes provided enhanced arsenic removal tendency without compromising the retention permeability.

Insights into the Surface Science, Storage Mechanism and Electrochemical Phase Evolution of MoS2/CNT Hybrid Electrodes for Supercapacitive Application

Lately, layered MoS2 is found to be one of the most researched pseudocapacitive electrode material for Li+ and Na+ ion batteries because of its unique layered structure for initial ion intercalation and de‐intercalation and high conversion chemistry. As far as supercapacitors are considered, the charge storage in nanostructured MoS2 takes place via electric double layer formation, intercalation and de-intercalation pseudocapacitance and redox pseudocapacitance. Recently, a vast majority of studies on layered MoS2, have been focused on designing hierarchical deformed structures instead of regularly ordered crystallites which may accommodate intercalation stress upto some extent while retaining the original structure. In this study, we have synthesized large aspect ratio carbon nanotubes with a high specific surface area and an appropriate superstructure forming a thin layer of molybdenum disulfide nanoflakes hierarchically dispersed on the surface of the CNTs. This novel technique of preparing MoS2@CNT superstructure using a combination of chemical and physical deposition techniques proved to be very efficient in structurally engineering the microstructure of electrode material. Moreover, sputtering as a fabrication technique, provided an opportunity to precisely grow hierarchical structured MoS2 nanoflakes uniformly throughout the matrix, easily scalable and controllable at lengths down to nanometer ranges irrespective of superhydrophobic nature of CVD grown CNTs. The designed hybrid nanostructure form an open porous network with shorter ionic as well as electron diffusion lengths and provides larger number of intercalation sites. The super capacitive measurements of the MoS2@CNT electrode revealed capacity of 337 mF/cm2 at the sweep rate of 5 mV/s. The storage mechanism involves both electrostatic ionic adsorption as well as Na+ intercalation into the MoS2@CNT matrix. The electrochemical performance of the hybrid is far more superior due to the contribution from both faradaic and non-faradaic processes. Also, the cyclic retention have been immensely improved as compared to bare CNT and MoS2 and has shown a retention of 97.6% after 3500 cycles. Further, to elucidate the charge storage mechanism Trasatti’s and Dunn’s analysis are performed which suggest that pseudocapacitive phenomenon is dominantly responsible for superior charge storage in the hybrid. The electrodes subjected to 10, 50, 1000, 2000 and 3500 charging discharging cycles at 100mV/s were then analyzed using X-ray photoelectron spectrophotometer to understand the change in surface science of the material and reason behind cyclic fading. The phase transformation of electrode suggests that the binding energies of MoS2 shits towards shifts towards lower energies after cycling. This shift indicates partial transition of 2H→1T MoS2 phase due to the transverse gliding of S plane upon the intercalation of electrolytic ions. Additionally, we observed the formation of thin MoO3 oxide layer on the surface of electrode which may be due to the presence of dangling bonds generated by ionic intercalation. Thus, this thin insulating layer may be the reason of capacitive fading after 3500 cycles of constant charging and discharging. The all solid state supercapacitor built using symmetric MoS2@CNT electrodes was found to have high areal and volumetric capacitance of 131 mF/cm2 and 2.9 F/cm3 respectively, with high cyclic stability of 97.6% after 2500 cycles. Figure 1

Adsorption mechanism of carboxymethyl cellulose onto mesoporous mustard carbon: Experimental and theoretical aspects

Carboxymethyl cellulose (CMC) is a versatile polymer for several industrial applications such as oil drilling, detergents, food and beverage, papers, ceramics, coatings, and other promising utilization. However, the deficiency for exploring the binding mechanism of the CMC onto the solid surfaces in aqueous system retards its applications. Herein, the binding aspect of CMC onto mesoporous mustard carbon (MMC) was illuminated where the BET analysis reveals that MMC had a surface area (SBET) = 16.576 m2 g−1, which was primarily contributed by mesopores (average pore diameter and total pore volume of MMC were found to be 12.432 nm and 0.051 cm3 g−1, respectively). The electrokinetic analysis demonstrated that the surface of the MMC is negatively charged with point of zero charge value 9.8 which favor the adsorption of CMC at particular pH value (pH = 3.0). The adsorption free energy of CMC was found as -22.561 kJ mol−1 which was in close agreement with H-bond energy suggesting hydrogen bonding as a governing parameter for CMC L2 type adsorption (also confirmed by high-resolution X-ray photoelectron spectrophotometer, attenuated total reflection Fourier transformation infra-red and urea test). A theoretical model of adsorbent-adsorbate complex (MMC-CMC) was considered in order to probe the interaction between the both. The structural, stability, electronic, and charge transfer features have been explained on the basis of binding energy, HOMO-LUMO gap, natural population analyses, Bader’s QTAIM analysis using DFT approach. The molecular electrostatic potential surface is calculated in probing the reactive sites of the system. Different forms of CMC aggregates stabilized by the HB(s)/π…π stacking, demonstrate varied structural and electronic properties. Such variations could have a significant assessment on the performance of food and pharmaceutical industries. Thus, an apparent overview of the binding aspects of CMC onto the MMC can endorse CMC as a potential adsorbate for various industrial applications.

Photocatalytic Degradation of Bisphenol-A using N, Co Codoped TiO2 Catalyst under Solar Light

Advanced oxidation processes (AOPs) including heterogeneous photocatalysis has proven as one of the best technique for waste-water treatment. Photocatalytic process using semiconductor like TiO2 based heterogeneous photocatalysis is a promising method for the treatment of toxic pollutants. In the present study, visible-light photoactive cobalt and nitrogen co-doped TiO2 nanoparticles were synthesized via wet impregnation method. The photocatalysts were characterized using X-ray diffraction (XRD), Raman Spectra, Fourier Transform Infrared (FTIR) Spectroscopy, Scanning Electron Microscopy (SEM), Transmission Electron Microscope (TEM), UV-vis spectrophotometer and X-ray photoelectron spectrophotometer (XPS). The photocatalytic activitiy of prepared (N, Co)-codoped TiO2 on the mineralization of Bisphenol-A (BPA) under visible light irradiation was studied and the results were compared to commercial TiO2 (Degussa P25). The results demonstrated that 1.5% Co and 0.5% N – codoped TiO2 samples revealed higher activity than commercial TiO2. Total organic carbon (TOC) removal was observed to be 97%, which indicate the complete mineralization of BPA. GC-MS analysis was carried to find out the possible intermediates formed and reaction pathway.

Fabrication of robust biomimetic coating by integrated physisorption/chemical crosslinking technique

Intrinsic hydrophobicity of polymeric biomedical devices generally causes adverse complications (i.e. thrombosis formation). In this study, biomimetic surface modification is conducted on different hydrophobic substrates (PP, PET and PTFE) by physisorption and subsequent UV induced chemical crosslinking of a ternary methacrylate copolymer bearing phosphorylcholine (PC), cholesteryl (Chol) and azidophenyl (Az) side groups, poly(MPC-co-CMA-co-AzMA) (PMCA). X-ray photoelectron spectrophotometer (XPS), atomic force microscopy (AFM) and water contact angle (WCA) measurements are used to monitor the changes in chemical composition, morphology and wetting behavior of the polymeric substrate surfaces before and after surface modification. The protein adsorption and platelet adhesion experiments are also performed to assess its antifouling properties. The results show that the synergistic contribution of physical anchor of Chol groups and chemical crosslinking of Az moieties leads to the formation of a highly crosslinked cell outer membrane mimetic coating with relatively uniform and dense nano-granular surface textures. The resultant PMCA modified surface exhibits greatly enhanced hydrophilicity due to the enrichment of hydrophilic phosphorylcholine moieties on the outer layer of PMCA coating. Particularly, compared with poly(MPC-co-CMA) (PMC) and poly(MPC-co-AzMA) (PMA) coatings, PMCA coating possesses good surface stability and interfacial adhesion performance. It provides the polymeric substrates with significantly improved antifouling property. The amounts of proteins and platelets adsorbed or adhered on PMCA modified surfaces could be reduced by at least 85% and 97% after incubation for 48 h, respectively. It offers a facile way to fabricate robust antifouling surface for the improvement of the biocompatibility of polymeric biomedical devices.

Synthesis, characterization and photodegradation activity of graphitic C3N4-SrTiO3 nanocomposites

Porous graphitic nitride (gC3N4) by template free simple condensation and SrTiO3 nanocubes by sol-gel method were synthesized. Composites containing Different percentages of pGCN were prepared (x% pGCN-ST where x = 5, 10, 30, 50 & 70%). The as synthesized composites were characterized by various instrumental techniques such as X-Ray diffractometer, Fourier transform infrared spectrophotometer, BET surface area analyzer, UV Visible diffuse reflectance spectrophotometer, X-Ray photoelectron spectrophotometer, SEM with Energy dispersive X-ray analyzer (SEM/EDAX) and elemental mapping, Transmission electron microscope, Photoluminescence spectrophotometer and Electrochemical impedance. The composite catalysts were evaluated for their photocatalytic degradation of reactive blue 198 (RB 198), reactive black 5 (RB 5) and reactive yellow 145 (RY 145) in the presence of visible irradiation. Among the different composites 50% pGCN-ST catalyst showed remarkable decolourization of all the three dyes under different irradiation (UV, visible and solar). Kinetics studies were revealed that the photodecolourization reaction followed pseudo first order. TOC and COD studies confirmed that the dyes were mineralized significantly. A possible mechanism for photocatalytic degradation was also proposed in this study.

Visible light photocatalytic activities of template free porous graphitic carbon nitride—BiOBr composite catalysts towards the mineralization of reactive dyes

Template free porous g-C3N4 (pGCN) and flower like bismuth oxybromide catalysts were synthesized by poly condensation and precipitation methods respectively. Various weight percentages of porous GCN-BiOBr composite catalysts (x% pGCN-BiOBr where x=5, 10, 30, 50 & 70wt% of pGCN) were synthesized by impregnation method. All the synthesized catalysts were characterized by X-Ray diffractometer, Fourier transform infrared spectrophotometer, BET surface area analyzer, UV Visible diffuse reflectance spectrophotometer, X-Ray photoelectron spectrophotometer, SEM with Energy dispersive X-ray analyzer (SEM/EDAX) and elemental mapping, Transmission electron microscope, Photoluminescence spectrophotometer and Electrochemical impedance. Photocatalytic degradation of all the synthesized catalysts were tested towards the harmful reactive dyes such as reactive blue 198 (RB 198), reactive black 5 (RB 5) and reactive yellow 145 (RY 145) in presence of visible irradiation. Among the catalysts 30% pGCN-BiOBr resulted in the highest photocatalytic activity towards the degradation of all the three dyes in presence of UV, visible and solar irradiations. Kinetics studies on the photocatalytic mineralization of dyes indicated that it followed pseudo first order. HPLC, TOC and COD studies confirm that the dyes are mineralized into CO2, water and mineral salts.

Synthesis of a fluorine-free polymeric water-repellent agent for creation of superhydrophobic fabrics

A non-fluorinated polymeric alkylsilane, poly(isobutyl methacrylate-co-3-methacryloxypropyltrimethoxysilane) (PIT), is designed and synthesized to replace the commercial long-chain perfluoroalkylsilane (FAS) water-repellent agent. The superhydrophobic polyester fabrics are prepared by anchoring sol-gel derived silica nanoparticles onto alkali-treated polyester fabric surfaces and subsequently hydrophobilizing with PIT, using FAS as control. The surface chemical composition, surface morphology, wetting behavior and durability of the modified polyester fabrics are characterized by scanning electron microscopy (SEM), X-ray photoelectron spectrophotometer (XPS) and video-based contact angle goniometer, respectively. The results show that a porous silica layer could be successfully fabricated onto the surface of polyester fabric through base-catalyzed sol-gel process with tetraethoxysilane (TEOS) as precursor, incorporating additional nanostructured roughness essential for superhydrophobicity. At the same time, such a silica primer layer could provide both secondary reactive moieties (−Si − OH) for the subsequent surface hydrophobization and acceptable adhesion at the silica-polyester fabric interface. When silica modified polyester fabric (SiO2@ fabric) is hydrophobized by PIT solution (10mg/mL), excellent water-repellency could be obtained. The water contact angle is up to 154° and the sliding angle is about 5°. Compared with small molecule water-repellent agent FAS, PIT modified SiO2@ fabric exhibits greatly improved solvent resistance under ultra-sonication, abrasion and simulated laundering durability. The anti-stain property of PIT-modified SiO2@ fabric is also evaluated by using different aqueous colored solutions.

Biomimetic surface modification of polypropylene by surface chain transfer reaction based on mussel-inspired adhesion technology and thiol chemistry

Biomimetic surface modification of polypropylene (PP) is conducted by surface chain transfer reaction based on the mussel-inspired versatile adhesion technology and thiol chemistry, using 2-methacryloyloxyethylphosphorylcholine (MPC) as a hydrophilic monomer mimicking the cell outer membrane structure and 2,2-azobisisobutyronitrile (AIBN) as initiator in ethanol. A layer of polydopamine (PDA) is firstly deposited onto PP surface, which not only offers good interfacial adhesion with PP, but also supplies secondary reaction sites (-NH2) to covalently anchor thiol groups onto PP surface. Then the radical chain transfer to surface-bonded thiol groups and surface re-initiated polymerization of MPC lead to the formation of a thin layer of polymer brush (PMPC) with cell outer membrane mimetic structure on PP surface. X-ray photoelectron spectrophotometer (XPS), atomic force microscopy (AFM) and water contact angle measurements are used to characterize the PP surfaces before and after modification. The protein adsorption and platelet adhesion experiments are also employed to evaluate the interactions of PP surface with biomolecules. The results show that PMPC is successfully grafted onto PP surface. In comparison with bare PP, the resultant PP-PMPC surface exhibits greatly improved protein and platelet resistance performance, which is the contribution of both increased surface hydrophilicity and zwitterionic structure. More importantly, the residue thiol groups on PP-PMPC surface create a new pathway to further functionalize such zwitterion modified PP surface.

Removal of Pb(II) and Cd(II) ions from aqueous solution by thiosemicarbazide modified chitosan

The removal of Pb(II) and Cd(II) ions from aqueous solution by thiosemicarbazide modified chitosan (TCS) was studied in this article. The synthesized TCS was characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), element analysis, N2 adsorption-desorption, scanning electron microscopy (SEM) and X-ray photoelectron spectrophotometer (XPS). Moreover, the influence of solution pH, contact time, initial heavy metal concentration, and solution temperature on the adsorption process was examined, and the adsorbent reusability and adsorption mechanisms were also studied. The results showed that TCS adsorbed greater amount of Pb(II) and Cd(II) ions than the raw chitosan. The adsorption amounts of Pb(II) and Cd(II) ions were affected by increasing solution pH and temperature. The maximum adsorption capacities of the TCS for Pb(II) and Cd(II) ions were found to be 325.2 and 257.2mg/g, respectively. The endothermic adsorption fitted the pseudo-second-order kinetics equation and the adsorption isotherms could be well described by Langmuir model. The metal ions adsorption mechanism was concluded to be mainly dominated by complexation reaction process. The desorption study indicated that the target adsorbent was easy to be regenerated.

Synthesis of polymeric fluorinated sol–gel precursor for fabrication of superhydrophobic coating

A fluorinated polymeric sol–gel precursor (PFT) is synthesized by copolymerization of 2,3,4,5,5,5-hexafluoro-2,4-bis(trifluorinated methyl)pentyl methacrylate (FMA) and 3-methacryloxypropyltrimethoxysilane (TSMA) to replace the expensive long chain fluorinated alkylsilanes. The fluorinated silica sol is prepared by introducing PFT as co-precursor of tetraethyl orthosilicate (TEOS) in the sol–gel process with ammonium hydroxide as catalyst, which is then used to fabricate superhydrophobic coating on glass substrate through a simple dip-coating method. The effects of PFT concentrations on the chemical structure of the formed fluorinated silica, the surface chemical composition, surface morphology, wetting and self-cleaning properties of the resultant fluorinated silica coatings were studied by using X-ray powder diffraction (XRD), Fourier transform infrared spectrometer (FTIR), X-ray photoelectron spectrophotometer (XPS), scanning electron microscopy (SEM) and water contact angle measurements (WCA). The results show that the fluorinated silica sols are successfully obtained. The size and size distribution of the fluorinated silica particles are found greatly dependent on the concentration of PFT, which play a crucial role in the surface morphology of the corresponding fluorinated silica coatings. The suitable PFT concentration added in the sol–gel stage, i.e. for F-sol-1 and F-sol-2, is helpful to achieve both the low surface energy and multi-scaled microstructures, leading to the formation of the superhydrophobic coatings with bio-mimicking self-cleaning property similar to lotus leaves.

Enhanced chromium (VI) adsorption using nanosized chitosan fibers tailored by electrospinning

Stacked chitosan nanofibers with an average diameter of 75nm were successfully produced by electrospinning using 5wt% chitosan in acetic acid as the spinning solution. The fibers were then cross-linked with glutaraldehyde to remove chromium [Cr(VI)] from water via static adsorption. It was found that the adsorption correlated well with pseudo-second order kinetic model, and followed a mixed isotherm of Freundlich and Langmuir. The maximum nanofibers adsorption capacity was 131.58mg/g, more than doubled that of chitosan powders. Common co-ions such as Cl−, NO3−, Na+, Ca2+ and Mg2+ had little or no effect on the adsorption but SO42− was an exception. Fourier transform infrared spectroscopy and X-ray photoelectron spectrophotometer analyses indicated that both amino and hydroxyl groups of chitosan were engaged in the adsorption.

Preparation and Characterization of Cd<sub>1-x</sub>Zn<sub>x</sub>S Thin Films with Chemical Bath Deposition

Cd1-xZnxS thin films were grown on soda-lime glass substrates by chemical-bath deposition (CBD). The surface morphology, thickness, composition, state of the constituent elements and optical properties of the films were studied with X-ray diffraction (XRD), scanning electron microscopy (SEM), step height measurement instrument, X-ray photoelectron spectroscopy (XPS) and spectrophotometer, respectively. The affect of annealing for the Cd1-xZnxS thin films was studied. The Cd1-xZnxS thin films had cubic crystal structure and the average transmittance was 86.8% in the visible range with the optical band gap of 2.61eV and the films thickness was about 50nm. The atomic ratio of (Cd + Zn): S increased after annealing.

Degradation Behavior of Pure Polystyrene Subjected to Two Natural Climate Types and the Simulated Effect of Artificial Accelerated Weathering

Pure polystyrene (PS) was subjected to natural weathering in Qionghai (QH) and Ruoqiang (RQ) of China, representing hot and humid climate and xerothermic climate respectively. The degradation profile of pure PS was studied by Fourier Transform Infrared (FTIR) Spectroscopy, Differential Scanning Calorimetry (DSC), Scanning Electron Microscope (SEM), X-ray Photoelectron Spectroscopy (XPS) and Spectrophotometer. Artificial accelerated weathering tests protocol A and B were carried out to simulate hot and humid climate and xerothermic climate respectively. Results show that pure PS degrade slowly at the initial stage and then become faster. Color shift could be an appropriate indicator for evaluating simulated effect of artificial accelerated weathering and protocol A simulate hot and humid climate perfectly while protocol B turns out weak for xerothermic climate.

Layer-by-Layer Structured Membranes of Silk Fibroin and Polyethylenimine on Electrospun Silk Fibroin Nanofibers

Self-assembled silk fibroin (SF)-polyethylenimine (PEI) multilayered films were fabricated on ethanol treated electrospun SF nanofibrous substrates via the electrostatic layer-by-layer (LBL) adsorption. The film coated membranes were characterized using scanning electron microscopy (SEM), transmission electron microscope (TEM) and X-ray photoelectron spectrophotometer (XPS). The SEM images showed that the multilayers of SF-PEI were formed on the surface of the ethanol treated SF nanofibres. The characteristics such as the fiber shape and porous structure were well maintained as the number of the coated SF-PEI bilayers was less than five. However, obvious adhesive substances and blocked pores were observed on the surface of the fibers as the number of bilayers of SF-PEI increased to six. Furthermore, the obvious core-shell structures were observed by TEM. The thickness of five SF-PEI bilayers was approximately 80nm. Additionally, the XPS results also revealed that the SF-PEI multilayer composite membranes formed. The adsorption mainly depended on a simple electrostatic interaction between the layers of SF and PEI. These SF-PEI multilayer assembled nanofibrous membranes could be a promising material for use as a sensor, gene delivery agent and scaffolds.