A series of tungsten-containing mesoporous SBA15 with different tungsten contents were prepared through a direct co-condensation sol–gel method and then analyzed by various techniques. XRD patterns revealed that the original mesoporous morphology was maintained after introducing tungsten species and forms of tungsten species were changed from incorporated tungsten to isolated tungsten species or low oligomeric tungsten oxide species, and finally to crystalline WO3 with the increase of tungsten precursor content, which were also proven by HRTEM images, UV–Vis DRS, and FT-IR spectra. The W-SBA15 samples exhibited satisfactory photocatalytic performance toward degradation of dye Rhodamine B (RhB) and 2,4-dichlorophenol (2,4-DCP). In particular, the best candidate, sample 10%W-SBA15 showed an apparent reaction rate constant for RhB that was nearly 10 times as high as that of bulk WO3. The enhancement of photocatalytic capability was attributed to the mesoporous morphology with enlarged surface areas, negatively charged surface, and favorable tungsten forms such as incorporated tungsten, isolated tungsten or low oligomeric tungsten oxide species. In addition, active radicals trapping experiments and DMPO spin-trapping ESR spectra indicated that photogenerated holes were major oxidative species during photocatalysis.

•A series of tungsten-titanium-cocontained SBA15 composites were fabricated by a simple synthetic route.•These samples showed enhanced catalytic performance in comparison to those comprising bare tungsten or titanium component.•The enhancement of photocatalytic behavior under visible-light irradiation was discussed.A facile and one-step hydrothermal procedure was adopted to fabricate a series of W-Ti-SBA15 composites (WTS). These as-prepared composites were systematically characterized by a collection of analytic and spectroscopic techniques. It was found that dual phases of titanium and tungsten species coexisted in mesoporous structures of p6 mm hexagonal symmetry. In addition, these composites were visible-light responsive and exhibited enhanced photocatalytic capability toward degradation of Rhodamine B (RhB) and 2,4-dichlorophenol (2,4-DCP) upon visible-light irradiation in comparison to samples containing single component of titanium or tungsten species. Specifically, the best candidate, sample 8%WTS0.7, had the largest apparent reaction rate constant that was nearly 1.2, 2.1, 2.2, and 5.7 times as high as those of 8%WS, TS0.7, WO3/TiO2, and N-TiO2, respectively. The enhancement of photocatalytic performance was mainly attributed to the well-matched band structures of both components and strengthened visible-light adsorption ability, originating from the combination of titania with highly acidic WO3 in SBA15 matrix with large specific surface areas. Active radical species were detected by trapping experiments and a possible photocatalytic mechanism was thus proposed.

•W-Ti-SBA15 composites with low TiO2/SiO2 mass ratios and their Ag-contained analogs were fabricated.•These composites showed enhanced photocatalytic performance in comparison to those with high TiO2/SiO2 mass ratios.•Photocatalysis mechanism of these Ag-W-Ti-SBA15 plasmonic composites was proposed.A group of mesoporous WO3-TiO2-contained SBA15 composites (W-Ti-SBA15) and their Ag-contained plasmonic analogs were fabricated and then systematically characterized by a collection of analytical techniques. Original mesoporous structures with highly ordered channels were well-maintained and WO3-TiO2 could form spherical clusters that were gradually reduced in size accompanying with the decrease of TiO2/SiO2 mass ratios. Deposited Ag species were confirmed as zero-valence Ag by X-ray photoelectron spectroscopy analysis and exerted almost no effect on the morphology, microstructure, and textural but optical property, by which the visible-light harvesting ability of composites was remarkably strengthened owing to the localized surface plasmonic resonance (LSPR) induced by the metallic Ag. Under visible-light irradiation, W-Ti-SBA15 composites showed satisfactory photocatalytic performance that could be further enhanced by using their Ag-contained ternary plasmonic analogs. The enhancement of photocatalytic efficiency was mainly attributed to the favorable mesoporous morphology, the suitable band alignment, and the LSPR effect. Eventually, a possible photocatalysis mechanism was primarily proposed on the base of reactive radical species trapping experiments.

The catalytic photo-oxidation of 3,4-dihydroxybenzoic acid on TiO2 has been studied by in situ ATR-FTIR in flowing water and in flowing wet air/nitrogen gas. In flowing water it was difficult to observe photodegradation intermediates despite photocatalytic action during UV illumination. In the flowing wet air/nitrogen system carboxylic acids and carbonates were observed. It was shown that water plays an important role in the formation of oxidation active species. Oxygen shows a prominent role for carboxylic acid degradation, but the photogenerated hole plays the important role for the 3,4-dihydroxybenzoic acid ring cleavage.

The photolysis of tetrabromobisphenol A (TBBPA) in aqueous solution under simulated solar light irradiation was studied under different conditions to find out mechanisms and pathways that control the transformation of TBBPA during photoreaction. Particular attention was paid to the identification of intermediates and elucidation of the photolysis mechanism of TBBPA by UPLC, LC/MS, FT-ICR-MS, NMR, ESR, and stable isotope techniques (13C and 18O). The results showed that the photolysis of TBBPA could occur under simulated solar light irradiation in both aerated and deaerated conditions. A magnetic isotope effect (MIE)-hydrolysis transformation was proposed as the predominant pathway for TBBPA photolysis in both cases. 2,6-Dibromophenol and two isopropylphenol derivatives were identified as photooxidation products of TBBPA by singlet oxygen. Reductive debromination products tribromobisphenol A and dibromobisphenol A were also observed. This is the first report of a photolysis pathway involving the formation of hydroxyl-tribromobisphenol A.

A series of novel oxygen-rich bismuth oxychloride (Bi12O17Cl2) were synthesized through a facile poly(vinyl pyrrolidone) (PVP)-assisted hydrothermal route. These obtained Bi12O17Cl2 samples were characterized by various physicochemical techniques. It was found that a proper addition amount of PVP could promote the transformation of Bi12O17Cl2 morphology from irregular clusters to three-dimensional hierarchical flower-like microspheres that were nominated as sample BP2. As-synthesized samples were subjected to a photocatalytic degradation of dye Rhodamine B (RhB) or 2,4-dichlorophenol (2,4-DCP) under visible light. Among all candidates, the sample BP2 with a hierarchical flower-like morphology showed the best degradation efficiency for RhB and 2,4-DCP. The apparent rate constant of sample BP2 in terms of degradation of RhB was nearly 5.7 and 45 times that of unmodified BP0 and N-TiO2. The enhanced photocatalytic performance could be ascribed to synergetic effects including unique hierarchical morphologies, large specific surface area, small particle size, good crystallinity, and suitable band structures. A possible mechanism of catalytic degradation was finally proposed basing upon the active species trapping experiments.

Exfoliated g-C3N4 nanosheets (CNs) were composited with bismuth oxychloride (BiOCl) to fabricate a series of hybrids via a facile chemical deposition–precipitation method in this investigation. The as-synthesized BiOCl–CNs hybrids were then fully characterized by a collection of analytical techniques. It was obviously observed that CNs were in intimate contact with hierarchical BiOCl flowerlike units to form heterojunction structures, which facilitates transfer and efficient separation of photoinduced electron–hole pairs, thus greatly increasing catalytic activity upon visible light irradiation. Together with other merits such as enlarged specific surface area, favorable optical properties, and suitable energy-band structures, these robust BiOCl–CNs hybrids showed significantly enhanced photocatalytic performance towards Rhodamine B (RhB) dye removal. Under identical conditions, the apparent photocatalytic reaction rate of the best hybrid BiOCl–CNs-3% was about 2.1 and 26.6 times as high as those of BiOCl and CNs alone, respectively. A possible photocatalytic mechanism was also proposed by means of active species trapping measurements, revealing that superoxide radicals (˙O2−) played a crucial role during the catalytic process.

•BiOBr hybrids were facilely synthesized with exfoliated g-C3N4 nanosheets.•These hybrids showed apparently higher catalytic efficiency than BiOBr and CNs alone.•Excellent degradation performance of hybrids was attributed to the favorable physical and optical features.•Possible photocatalytic degradation mechanism was proposed basing active species trapping experiments.Exfoliated g-C3N4 (CNs)–BiOBr hybrids with heterojunction structure was fabricated through a chemical deposition–precipitation route. The characterization showed the uniform existence of CNs and BiOBr in hybrids. The fabricated CNs–BiOBr was of enlarged specific surface area, unique optical property, and well-matched energy-band structures. The photocatalytic performance on dye Rhodamine B (RhB) and 2,4-diclorophenol (2,4-DCP) were dramatically improved. Under identical conditions, sample 0.5CNs–BiOBr and CNs–BiOBr were identified as the best candidate, respectively, for catalytic degradation of RhB and 2,4-DCP. The former could show a reaction rate over RhB about 2.7 and 6.8 times as high as BiOBr and CNs alone, and the later exhibited a reaction rate over 2,4-DCP nearly 7.5 and 2.5 times as high as individual BiOBr and CNs. Finally, a possible catalytic mechanism was also proposed through active species trapping experiments.A series of novel CNs–BiOBr hybrids with heterojunction structure were fabricated and subjected to the photocatalytic degradation of Rhodamine B and 2,4-diclorophenol under visible light illumination. The enhancement of catalytic ability was explained and a possible mechanism was proposed as well.

Pure and Pt nanoparticle-modified rutile TiO2 were synthesized via hydrolysis of TiCl4 in the absence or presence of Pt nanoparticles. HRTEM, XRD, and SEM were used to characterize the structure of the prepared catalysts. The resulting modified TiO2 catalysts show extended visible light absorbance. Photodegradation of 2,4,6-trichlorophenol (2,4,6-TCP) over these photocatalysts was investigated under visible light illumination. The Pt nanoparticles facilitate the separation of photogenerated electron–hole pairs at low Pt content, then enhances the photodegradation rate of 2,4,6-TCP. 0.18Pt–TiO2 achieved the best photocatalytic activity among the tested catalysts. It was found that singlet oxygen rather than ˙OH acts as the main oxidative species for the degradation of 2,4,6-TCP according to the experimental results. The degradation intermediates of 2,4,6-TCP were identified and the degradation pathway was proposed. Pt nanoparticles on TiO2 significantly enhance O2 adsorption and the formation of ˙O2−. The rutile surface is a favorable condition for stabilizing ˙O2−. These properties of the Pt nanoparticle-modified rutile TiO2 facilitate the formation of 1O2via the reaction of superoxide anions with holes.

The oxidase and dioxygenase reactions of 3,5-di-tert-butylcatechol (DTBC, I) in the presence of V-polyoxometalate were studied. It was found that the addition of a Lewis base quenched the V-polyoxometalate-catalysed catechol dioxygenase reaction and catalysed the oxidase reaction selectively. The existence of V-polyoxometalate accelerates the autoxidation rate of I as demonstrated by the rate measurements. ESR and UV-VIS spectra showed that the Lewis base destroyed the dioxygenation reaction catalyst as formed and restrained its regeneration by suppressing the coordination of catechol radical to vanadium. The by-products of the dioxygenation and oxidation reactions are H2O and H2O2, respectively.

A series of aluminum oxyhydroxide-incorporated titania composites were prepared by a one-pot synthetic procedure using aluminum tri-sec-butoxide as a precursor. The as-synthesized samples were characterized by Fourier transform infrared spectrophotometer, X-ray diffraction, thermogravimetry and differential scanning calorimetry, nitrogen physisorption, and scanning electron microscopy. It was identified that aluminum oxyhydroxide (γ-AlOOH, or boehmite) was produced as aluminum matrix into which titania, commercially available P25, was incorporated. Photocatalytic activity of all nanocomposites was evaluated with respect to the photodecolorization of methyl orange under UV irradiation and almost complete decolorization was eventually achieved under optimum experimental conditions.

Nine monoazathiacrown ethers have been synthesized and explored as ionophores for polymeric membrane Ag+-selective electrodes. Potentiometric responses reveal that the ion-selective electrodes (ISEs) based on 2,2′-thiodiethanethiol derivatives can exhibit excellent selectivities toward Ag+. The plasticized poly(vinyl chloride) membrane electrode using 22-membered N2S5-ligand as ionophore has been characterized and its logarithmic selectivity coefficients for Ag+ over most of the interfering cations have been determined as <−8.0. Under optimal conditions, a lower detection limit of 2.2 × 10−10 M can be obtained for the membrane Ag+-ISE.

•Novel Ag/Bi12O17Cl2 plasmonic composites were constructed.•These composites showed apparently higher catalytic efficiency than Bi12O17Cl2 alone.•Excellent degradation owned to the favorable physical and optical features of samples.•A possible photocatalytic degradation mechanism was proposed.In this investigation, novel Ag/Bi12O17Cl2 plasmonic composites with different Ag contents were constructed through a solvothermal and subsequent photoreduction route and fully characterized by a collection of analytical techniques. Spectroscopic results confirmed the presence and uniform dispersion of Ag nanoparticles on the 2D nanosheets of Bi12O17Cl2. The Ag content in composites exerted considerable influence on the extension of light-adsorption range and the enlargement of specific surface areas. The photocatalytic abilities of these Ag/Bi12O17Cl2 composites were evaluated toward the degradation of rhodamine B (RhB) and 2,4-dichlorophenol (2,4-DCP) under the visible-light irradiation. The results demonstrated that the Ag/Bi12O17Cl2 composites showed much higher photocatalytic efficiencies than that of pure Bi12O17Cl2, especially the sample with an optimal Ag content showing the best photocatalytic behavior among all tested samples. The remarkable enhancement of Ag/Bi12O17Cl2 photocatalytic efficiency could be mainly attributed to the efficient charge separation that was induced by the localized surface plasmon resonance effect of metallic Ag, strong visible-light adsorption and the favorable morphology with enlarged specific surface areas. Eventually, the photocatalysis mechanism over Ag/Bi12O17Cl2 composites was preliminarily proposed on the base of reactive species trapping experiments.Download full-size image