On-Line pH Measurement Cation Exchange Kinetics of Y3+-Exchanged Alginic Acid for Y2O3 Nanoparticles Synthesis.

A new sol-gel method that employs cation exchange from an aqueous metal ion solution with H+ ions of granulated alginic acid was developed for synthesizing high-purity Y2O3 nanoparticles. In this study, the cation exchange kinetics of H+~Y3+ in aqueous solution were analyzed using on-line pH technology and off-line inductively coupled plasma-atomic emission spectrometry (ICP-AES) analysis. Pseudo 2nd-order models were utilized to evaluate the parameters of the kinetics, suggesting that the concentration of H+~Y3+ involved in the cation exchange reaction was 1:1.733. Further, a comprehensive understanding of the Y-ALG calcination process was developed using thermo-gravimetric analysis, along with results obtained from differential scanning calorimetry (TGA/DSC). A detailed analysis of the XRD Rietveld refinement plots revealed that the crystallite sizes of Y2O3 nanoparticles were about 4 nm (500 °C) and 15 nm (800 °C), respectively. Differential pulse voltammetry (DPV) was employed to investigate the electrochemical oxidation of catechol. The oxidation peak currents of catechol at Y2O3 (500 °C)/GCE and Y2O3 (800 °C)/GCE showed two stages linear function of concentration (2.0~20.0 × 10-6 mol/L, 20.0~60.0 × 10-6 mol/L). The results indicated that the detection limits were equal to 2.4 × 10-7 mol/L (Y2O3 (500 °C)/GCE) and 7.8 × 10-7 mol/L (Y2O3 (800 °C)/GCE). The study not only provided a method to synthesize metal oxide, but also proposed a promising on-line pH model to study cation exchange kinetics.

Exploring the activation pathway of photo-induced electrons in facets-dependent I-doped BiOCl nanosheets for PCPNa degradation.

Electrons can degrade pentachlorphenate sodium (PCPNa) directly or activate molecular oxygen to produce·O2-and ·OH for its degradation. However, less work has been performed to control such two kinds of reaction pathway by modifying BiOCl. Herein, we firstly regulated the reaction pathway between electrons and PCPNa by adjusting the amount of surface oxygen vacancies (OVs) and surface adsorbed hydroxyl groups in I-doped BiOCl exposed with different facets. OVs on (001) facets-exposed I-doped BiOCl enabled large amount of PCPNa to adsorb on its surface and facilitated the direct reaction between electrons and PCPNa. In contrary, more surface adsorbed hydroxyl groups and oxygen on (010) facets-exposed I-doped BiOCl can retard the direct reaction between electrons and PCPNa via lowering the adsorption of PCPNa and increasing the activation of molecular oxygen by electrons. Although more·O2-and ·OH generated in I-doped (010)-facets exposed BiOCl, I-doped (001)-facets exposed BiOCl exhibited better photocatalytic activity. We proposed that the direct reaction between electrons and PCPNa can enhance the utilization efficiency of photogenerated electrons and improve photocatalytic degradation efficiency of PCPNa.

Evolution of Surface Oxidation on Ta3N5 as Probed by a Photoelectrochemical Method.

In this work, we present an in situ method to probe the evolution of photoelectrochemically driven surface oxidation on photoanodes during active operation in aqueous solutions. A standard solution of K4Fe(CN)6-KPi was utilized to benchmark the photocurrent and assess progressive surface oxidation on Ta3N5 in various oxidizing solutions. In this manner, a proportional increase in the surface oxygen concentration was detected with respect to oxidation time and further correlated with a continuous decline in the photocurrent. To discern how surface oxidation alters the photocurrent, we experimentally and theoretically explored its impact on the surface carrier recombination and the interfacial hole transfer rates. Our results indicate that the sluggish photocurrent demonstrated by oxidized Ta3N5 arises because of changes in both rates. In particular, the results suggest that the N-O replacement present on the Ta3N5 surface primarily increases the carrier recombination rate near the surface and to a lesser degree reduces the interfacial hole transfer rate. More generally, this methodology is expected to further our understanding of surface oxidation atop other nonoxide semiconductor photoelectrodes and its impact on their operation.

A green route to prepare metal-free phthalocyanine crystals with controllable structures by a simple solvothermal method.

Exploring the environmentally friendly and low-cost synthesis strategies of phthalocyanine (Pc) crystals in just one step is an absolute challenge. The solvothermal synthesis of phthalocyanine crystals shows the advantages of high-quality crystalline products, facile reaction and purification, and low cost. Nevertheless, only a few metal phthalocyanine crystals have been successfully synthesized via solvothermal reactions. In this study, we found that the crystalline ß metal-free phthalocyanine needles could be directly prepared via the tetrapolymerization of phthalodinitrile catalyzed by DBU in solvothermal reactions. Similar to the preparation of ß-phthalocyanine crystals, the α metal-free phthalocyanine crystals with the specific multiply-laminated structures can be obtained through solvothermal reactions assisted by DBN. SEM characterization showed that the individual ß metal-free phthalocyanine has a well-defined quadrangular shape with smooth faces. However, the α metal-free phthalocyanine exhibits a distinctive undulating surface morphology. Both phthalocyanines showed satisfactory thermal stability (from room temperature to about 300 °C), excellent resistance to acid/alkali solution, and fast photoelectric response properties (order of magnitude of response time, 10-6 s) as tested by TG-DSC and TPV, respectively. It is noted that ethanol was used as the reaction medium and the resulting phthalocyanine crystals can be facilely purified using hot ethanol to dissolve the impurities adsorbed on the surfaces of phthalocyanine crystals. Compared to the traditional methods, no re-crystallization operation was carried out for our method. To the best of our knowledge, this is the first report on the solvothermal synthesis of metal-free phthalocyanine crystals with controllable crystal form adjusted by DBU/DBN in one step.

Photoelectrochemical NADH regeneration is highly sensitive to the nature of electrode surface.

(Photo)electrochemistry enables the synthesis of high-value fine chemicals and highly selective activation of molecules that are difficult to prepare using conventional chemical methods. In this work, light-driven NADH (reduced nicotinamide adenine dinucleotide) regeneration is achieved using a molecular Rh(III) mediator on Si photoelectrodes. This process is observed to be highly sensitive to the surface nature of Si photoelectrodes, exhibiting an overpotential reduction up to 600 mV on Si nanowires (SiNWs) as compared to planar Si. The use of a molecular mediator and SiNWs enables 100% selectivity toward NADH synthesis within a broad potential window. The origin of the striking difference is identified as the multifaceted nature of SiNWs.

Surface chemistry and photoelectrochemistry-Case study on tantalum nitride.

Solar water splitting promises a solution to challenges associated with the intermittent nature of solar energy. Of different implementations, photoelectrochemical water splitting, where one or more photoelectrodes harvest light and catalyze water splitting, represents a convenient platform to understand the governing principles of charge behaviors, especially at the light absorber|H2O interface. This Perspective recognizes and discusses the importance of the photoelectrode surface to solar water splitting performance. It presents discussions within the context of a prototypical water splitting material, Ta3N5, which has gained growing attention lately for its outstanding initial performance. Insights into the mechanisms by which Ta3N5 functions are presented, followed by examples of recent efforts to circumvent the issues that Ta3N5 decays rapidly under solar water splitting conditions. Our visions on the future directions of semiconductor-based solar water splitting will be presented at the end.

A simple and facile bioinspired catalytic strategy to decolorize dye wastewater by using metal octacarboxyphthalocyanine particles.

To explore the simple, facile, environmental friendly and low cost catalytic technique to decolorize harmful dye contaminants in solution and understand the mechanism is an interesting and practical research. In this paper, we provide a highly efficient and convenient method for fast decolorization of dyes (methylene blue and rhodamine B) in aqueous solution catalyzed by iron octacarboxyphthalocyanine (FeOCPc) or cobalt octacarboxyphthalocyanine (CoOCPc). Compared to the traditional methods, our method is very simple. The 30 mg/L methylene blue could be decolorized almost absolutely less than 30 min just by dispersing FeOCPc powders into the dye solution. The decolorization of rhodamine B at high concentration (30 mg/L) could be achieved to 100% decolorization degree less than 20 min in the presence of FeOCPc and tert-butyl hydroperoxide (BuOOH). Moreover, the ESR and HPLC-MS measurement were performed to determine the active radicals and various intermediates in decolorization processes and the possible catalytic mechanism was proposed. It is noted that both FeOCPc and CoOCPc catalysts show the different catalytic oxidation behaviors depending on the oxidant (O2 or BuOOH). Our investigation provides a novel, low cost and convenient strategy to purify the environmental pollutions.

The efficient, fast and facile decolorization of organic dyes homogeneously catalyzed by iron octacarboxylic phthalocyanine.

To remove the harmful dye contaminants via an efficient, facile and low energy consumption route is a grave challenge in current chemical industry. Though the great progresses of TiO2 photocatalysis and enzymatic degradation have been witnessed, the strategy for satisfying the above requirements is still worth exploring. Herein, we develop a biomimetic catalysis strategy for the fast decolorization of organic dyes catalyzed by iron octacarboxylic phthalocyanine (FeOCPc) complexes assisted with tert-butyl hydroperoxide (BuOOH). Methyl orange (MO) and methylene blue (MB) were used as the model pollutants and experimental results show that the decolorization degree of 25 mg/L MO could achieve 100% within 20 min and 80% for 25 mg/L MB within 30 min. The molar ratio for FeOCPc/MO and FeOCPc/MB is 0.146 and 0.142, respectively. Interestingly, other than the high-valent iron-oxygen active species, tert-butyl peroxyl radicals and hydroxyl radicals were detected as the active species generated during the catalytic oxidation by the electron paramagnetic resonance (EPR) measurement. This work not only provides a distinctive biomimetic catalysis system of FeOCPc-BuOOH for the fast bleaching of dye pollutants, but also proposes the new insight on a mechanism based on the cooperation catalysis of iron-oxygen active species, tert-butyl peroxyl radicals and hydroxyl radicals.

Ethyl 4-hy-droxy-6-(4-hy-droxy-phen-yl)-4-trifluoro-methyl-2-sulfanyl-idene-1,3-diazinane-5-carboxyl-ate ethanol monosolvate.

The title compound, C(14)H(15)F(3)N(2)O(4)S·C(2)H(5)OH, was prepared by reaction of 4-hy-droxy-benzaldehyde, ethyl 4,4,4-trifluoro-3-oxobutano-ate and thio-urea. The hexa-hydro-pyrimidine ring adopts a half-chair conformation, the mean plane formed by the ring atoms excluding the C atom bonded to the eth-oxy-carbonyl group has an r.m.s. deviation of 0.0333 Å, and the dihedral angle between this plane and the benzene ring is 56.76 (5)°. The mol-ecular conformation is stabilized by an intra-molecular O-H⋯O hydrogen bond, generating an S(6) ring. The crystal structure is stabilized by inter-molecular O-H⋯O, O-H⋯S, N-H⋯O and N-H⋯S hydrogen bonds. The ethyl group of the ester unit is disordered over two positions, with an occupancy ratio of 0.757 (10):0.243 (10).

Photocatalysis effect of nanometer TiO2 and TiO2-coated ceramic plate on Hepatitis B virus.

The photocatalysis effect of nanometer TiO2 particles and TiO2-coated ceramic plate on Hepatitis B virus surface antigen (HBsAg) was investigated. The ELISA (enzyme-linked immunosorbent assay) standard method was used to assess the efficiency of TiO2 material to destroy the HBsAg. The research has shown that the suspension of TiO2 (0.5g/L) can destroy most of the HBsAg under the irradiation of mercury lamp, with the light intensity of 0.6mW/cm(2) at 365nm wavelength, or under the sunlight irradiation for a few hours. TiO2-coated ceramic plates can also destroy the HBsAg under the irradiation of mercury lamp, with the light intensity of 0.05mW/cm(2) at 365nm wavelength or under the room daylight for a few hours.

Novel photodegradable low-density polyethylene-TiO2 nanocomposite film.

A new type of photodegradable low-density polyethylene (LDPE)-TiO2 nanocomposite film was prepared by a melt blending technique. The photocatalytic degradation of the LDPE-TiO2 nanocomposites was investigated. The as-prepared films were characterized by scanning electron microscopy (SEM), high-temperature gel permeation chromatography (HT-GPC), X-ray photoelectron spectroscopy (XPS), FT-IR spectroscopy, and the photoinduced weight loss. The results show that the LDPE-TiO2 nanocomposite films could be efficiently degraded under UV or sunlight illumination. The weight loss rate of the composite film reached 68.38%, the average molecular weight (Mw) of the composite film decreased 94.56%, and the number of average molecular weight (Mn) decreased 93.75% after UV-light irradiation for 400 h. FT-IR and XPS analysis indicated that the LDPE was oxidized during UV-light irradiation. The photocatalytic degradation mechanism of the films is briefly discussed.