A series of Ce-doped TiO2 nanoparticles were prepared by a sol–gel process and characterized by XRD, SEM, TEM, EDX mapping, UV–vis DRS, Raman spectroscopy, N2 adsorption–desorption, PL spectra, CO2-TPD, and XPS. It is found that Ce ions can enter the lattice matrix of TiO2 and occupy of Ti sites. This atom replacement leads to the formation of impurity energy levels in the band gap of TiO2, extending light absorption into the visible light region. Because Ce has a more flexible valence state, both Ce3+ and Ce4+ could be formed in the composites. The preference facilitates the photoinduced charge separation inside of the crystals. Moreover, Pd nanoparticles were then loaded as a co-catalyst on the surface of doped composites. As the trapping center of electrons, it can efficiently adsorb and activate CO2 molecules, promoting their transformation into CH4. These composites were then evaluated as photocatalysts for CO2 hydrogenation. While all of them could efficiently catalyze the reaction, 1.0% Pd/0.5% Ce-TiO2 catalysts show the best photocatalytic performance, with CH4 and CO yields up to 220.61 and 27.36 μmol/g, respectively, under visible light irradiation of 3 h. The improved photocatalytic behavior could be possibly induced by the synergistic effect between Ce and Pd. A probable mechanism was thus proposed based on above characterizations and experimental results.

Titanium-based metal–organic frameworks (MOFs), named MIL-125 and NH2-MIL-125, have been successfully synthesized by the hydrothermal method. They were specially designed for the application of methylene blue (MB) removal from aqueous solution. The maximum adsorption capacity of MB was found to be 321.39 mg/g and 405.61 mg/g. The amount of dye that has been adsorbed 99.9% was 300 ppm within 20 and 120 intervals of time. The results show that NH2-MIL-125 is more effective in terms of both selectivity and capacity for the adsorption of MB cationic dye compared with MIL-125. The high adsorption selectivity was due to the unique electrostatic interaction between the amino groups of the dye molecules and NH2-MIL-125 but, on the other hand, owing to the more negative zeta potential (−32.4 mV), resulted from the charge balance for the protonation of −NH2. Moreover, reaction parameters including exposure time, adsorbent dose (0.02–0.05 mg), initial dye concentration (100–500 mg/L), and temperature were studied in detail. The adsorption processes in the two MOFs were determined to follow a pseudo-second-order pathway and obey a Langmuir isotherm model. Furthermore, the reaction was found to be spontaneous in nature yet thermodynamically an endothermic process. Characterization and structural analysis of the samples were evaluated by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectrometry, N2 adsorption/desorption (BET), X-ray photoelectron spectroscopy (XPS), and zeta potential.

Mesoporous Ce0.4Zr0.6O2 solid solutions with four different shapes, including mixed nanorod and nanoparticle (RP, cubic), nanopolyhedron (PH, tetragonal), nanosphere (SP, cubic) and nanoegg (EG, tetragonal), were hydrothermally fabricated. Various physical and chemical techniques were used to reveal shape-dependent structural, optical, electronic and surface properties, providing a powerful insight into the morphological dependence of photocatalytic activity towards methylene blue (MB) degradation. Among these samples, RP, consisting of a cubic Ce-rich phase (Ce0.6Zr0.4O2 nanorods) and a tetragonal Zr-rich phase (Ce0.2Zr0.8O2 nanoparticles), affords the optimal functionality, with a top degradation rate (D = 70.5%) and a peak rate constant (k = 0.0102 min−1). This occurrence results mainly from the prompt separation of excitons and suitable textural properties for MB absorption and activation. A brief introduction to the reaction path when using RP is proposed.

Although the conversion of cellulose to polyols is currently well-developed, the production of the considerably valuable ethylene glycol (EG) is still challenging. Reactions have long relied on the design of suitable catalysts to obtain a high selectivity and yield of EG. Herein, using well-shaped rectangular tungsten trioxide nanosheets as the substrate, we investigated the catalytic performances of various metal supported catalysts for the convertion of cellulose to EG. Results show that Ru/WO3 is more favorable for EG production, with the highest EG yield of 76.3% over the 1% Ru/WO3 nanosheet catalyst. Our characterizations and activity tests suggest that the embedding of Ru nanoparticles onto the WO3 nanosheets produces more W5+ active sites under the same reduction conditions (NaBH4 or H2), which act as Lewis base sites to promote the glucose retro-aldol condensation reaction. Moreover, the Ru/WO3 catalyst holds a portion of Ru in the form of amorphous RuOxδ+ phases, which could further increase the H+ released into an aqueous solution for cellulose hydrogenolysis. A possible catalytic mechanism for this hydrogenolysis process is accordingly proposed.

A series of Pd/TiO2 photocatalysts were synthesized by a simple glucose reduction method, and their photocatalysis properties were evaluated in an array of CO2 hydrogenations. The samples were characterized by XRD, SEM, TEM, EDX, EDX mapping, UV–vis DRS, Raman spectroscopy, PL spectroscopy, XPS, and N2 adsorption. In terms of product yields (in micromoles per gram of catalyst), a 1.0 wt % Pd/TiO2 catalyst (CH4, 355.62; CO, 46.35; C2H6, 39.69) was found to be superior to pristine TiO2 (CH4, 42.65; CO, 4.73; C2H6, 2.7) and other composites under UV irradiation for 3 h, possibly because of a synergistic effect between the palladium nanoparticles and the TiO2 support. The palladium nanoparticles on the surface of TiO2 substantially accelerated electron transfer and acted as active sites for the adsorption and activation of CO2 molecules, to promote CO2 hydrogenation. During the photocatalytic CO2 hydrogenation, dissociated hydrogen reacts with CO2– activated on the Pd/TiO2 photocatalyst to form a new Pd—C surface species that is stable during the reaction and further transforms to generate methane. A detailed mechanism of photocatalytic CO2 hydrogenation is discussed to account for the performance of the Pd/TiO2 photocatalyst in the reaction.

Boron-doped g-C3N4/Zn0.8Cd0.2S (BCN/ZS) has been prepared through a facile two-pot method and acted as an efficient photocatalysis material for degradation of methylene blue (MB) exposed to the Xe lamp. Construction of the ZS solid solution and BCN graphite-like structure, boron introduction into carbon sites in CN framework and formation of the hybrid structure between BCN and ZS are fully confirmed via various physical and chemical techniques. The last two structural factors are closely related to the enhanced photocatalytic function of the hybrids. Moreover, h+ and ˙O2− are testified as the major reactive species in MB photodegradation. Finally, the possible reaction path was proposed.

•MoS2 and MSx/MoS2 (M = Ni, Co, Ag) were prepared via the hydrothermal method.•Catalysis of MoS2 at various reaction conditions was examined.•A surprising conversion of lignin and yield of bio-oil was obtained with CoS2/MoS2.•Cooperation of different metallic sulfide could enhance the catalytic performance.Given the low price and abundance of alkali lignin from pulp and paper industry, the conversion of alkali lignin into valuable chemicals has been of great significance to address the world energy crisis. In principle, this process has long relied on the design of a functionalized catalyst to enable high reactivity and selectivity. Herein, we present a systematic study on the hydrogenation liquefaction of alkali lignin using a series of flower-like hierarchical MoS2–based catalysts, in which, the effect of various reaction parameters, such as temperature, H2 pressure, and reaction time, on product yield and distribution was evaluated. Catalysts were characterized by Powder X-ray diffraction, transmission electron microscopy and scanning electron microscopy. N2 adsorption-desorption isotherms, surface area, pore size distributions and the average pore diameter of catalysts were also measured and calculated. It is worth noting that the incorporation of a secondary metal sulfide into MoS2 could significantly enhance the catalytic performance. Particularly, by using 5 wt% CoS2/MoS2 as catalyst and having H2 pressure, reaction temperature, and reaction time set to be 2.5 MPa, 310 °C, and 1 h, respectively, the highest conversion of alkali lignin could reach 91.26%, with a bio-oil yield of 86.24%. This work thus offers an effective approach to improve the conversion and selectivity in catalytic hydrogenation of alkali lignin into bio-oil by using MoS2–based catalysts.

A novel composite material, MoS2/SrTiO3, has been successfully prepared via a two-step simple hydrothermal method. The photocatalytic performance of MoS2/SrTiO3 composites in the degradation of MO organic dyes under UV-light irradiation and the effect of the loading amount of MoS2 were investigated. For the first time, it was found that the as-prepared composites showed a high degradation rate and that the photocatalytic activity over pure SrTiO3 could be significantly enhanced by loading MoS2. Importantly, there is an optimal loading amount of MoS2 on the SrTiO3 in terms of degradation rate. In addition, the MoS2/SrTiO3 composite material with 0.05 wt% of MoS2 showed the best photocatalytic activity, with a degradation rate as high as 99.81% after 60 min irradiation time. The promoting effect caused by MoS2 can be due to the suppression of recombination between electrons and holes. This study demonstrates high potential for the development of environmentally friendly, cheap non-noble metal composite materials for photocatalytic degradation.

Correction for ‘Synthesis of MoS2/SrZrO3 heterostructures and their photocatalytic H2 evolution under UV irradiation’ by Qingwen Tian et al., RSC Adv., 2015, 5, 734–739.

A novel heterojunction of a MoS2/SrZrO3 photocatalyst was successfully synthesized via a simple hydrothermal process and applied to photocatalytic H2 evolution under UV light irradiation. The samples were characterized by X-ray diffraction, UV-vis absorption spectroscopy, scanning and transmission electron microscopy, X-ray photoemission spectroscopy, energy dispersive X-ray spectroscopy and EDX mapping. The heterostructure with an optimal content of 0.05 wt% MoS2 exhibits the highest H2 evolution rate of 5.31 mmol h−1. This is due to the junction between SrZrO3 and MoS2, which suppresses the recombination of photogenerated electrons and holes. Our work indicated that the prepared MoS2/SrZrO3 heterostructured photocatalyst can be used as an effective material for water splitting.

The catalytic conversion of alkali lignin to chemicals has been the subject of intense research efforts during the past few decades. In this study, VS2 catalysts, with different morphologies of sheets and nanoflowers, were prepared through hydrothermal methods and applied to the hydrogenation of alkali lignin. The conversion of alkali lignin and yield of bio-oil are 77.02 and 58.75%, respectively, at 250 °C under 2 MPa H2 for 1.5 h with a VS2 sheets catalyst, which is higher than that of a flower-like VS2 catalyst. It was found that mainly the components of bio-oil were phenols, important and useful chemicals in transportation fuels and chemical industries. Our results indicated that the prepared VS2 catalyst can be used as an effective material for degrading biomass to obtain valuable chemicals.

Water produced from alkaline–surfactant–polymer flooding technology is more difficult to treat than that from water flooding. In this study, a novel magnetic demulsifier, called M-5010, was synthesized through the reaction of 5010, a type of demulsifier currently used in oilfields, and epoxy group functionalized Fe3O4@SiO2 microspheres. The oil removal rates and effect of the demulsifier dosage as well as the settling time were investigated. It was found that the oil removal rate of M-5010 was higher than that of 5010 under the same conditions. In addition, M-5010 can be recycled and reused by using an external magnetic field that acts as a material phase separator. Accordingly, we found that M-5010 is still effective after being reused for 5 cycles. Our results indicate that the magnetic demulsifier we fabricated can be used as an effective and recyclable material for the removal of oil from oil contaminated wastewater.

Nanosized photocatalysts have been shown to be important to many modern photocatalytic reactions. Control of the microstructure of the nanocrystals enables regulation of their optical properties and enhancement of specific reactions. Here, Cu2+-doped ZnS nanosphere photocatalysts with hierarchical nanostructures and controllable sizes were synthesized via a facile wet-chemical reaction. We demonstrated that small amounts of Cu2+ doping could give rise to the formation of a variety of localized, nanosized Cu1−xZnxS solid solutions that are separated by a continuous ZnS medium. The nano-solid-solutions have predictable band structures and an average size of several nanometers, which ensure facile generation of electron–hole pairs by visible light irradiation and quick migration of the photo-generated charges to the interfaces. With Ru as a cocatalyst, the as-prepared 0.5 mol% Cu2+-doped ZnS nanospheres showed a high H2 evolution rate of 1.03 mmol h−1, corresponding to a quantum efficiency of 26.2% at 425 nm. A hierarchical surface structure with a large surface area is considered crucial for the increased activity. Our work not only showed that the non-toxic metal chalcogenides achieve high efficiency but also provides a new concept of localized nano-solid-solution for photocatalytic applications.

Phosphors with controlled emission spectra are of great interest due to their application for white light emitting diodes. Herein, a new class of Sr3Y2(SiO3)6:Ce3+, Tb3+ phosphors were synthesized by a facile sol-gel combustion method. The phase structure, morphology, and luminescence properties of the phosphors were characterized by using powder X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and photoluminescence excitation and emission spectra, respectively. The results on luminescence properties indicated that co-doped Ce3+ ions served as UV-light sensitizers with excitation energy partially transferred to Tb3+ ions, leading to green emission from Tb3+. Particularly, the corresponding emitting colors of the phosphors could be well-tuned from deep blue (0.16, 0.05) to green region (0.25, 0.45) by adjusting the molar ratio of Ce3+/Tb3+.Sol-gel-combustion synthesis of Sr3Y2(SiO3)6:Ce3+, Tb3+ phosphors with energy transfer from Ce3+ to Tb3+ (The noble phosphors with continuously tunable emission from deep blue to green region)

•Cd0.5Zn0.5S decorated with nanosized NiS surface heterojunctions was fabricated.•The H2 evolution rate reached 1.4 mmol/h with a quantum yield of 33.9%.•The mechanism for the enhanced charge separation was rationalized.•NiS played the role of noble metal promoting electron transfer and H2 evolution.Up to now, most of the semiconductor photocatalysts can only achieve their high photocatalytic activity for hydrogen production with the loading of noble metals, such as Pt or Ru, as cocatalysts, which drastically increases the total cost of the designed photocatalyst. Herein, we report the design and fabrication of a highly efficient Cd0.5Zn0.5S photocatalyst decorated with nanosized NiS surface heterojunctions. The hydrogen evolution rate over this photocatalyst reached 1.4 mmol/h, with a remarkable quantum yield of 33.9%. This efficiency is even much higher than many noble metal loaded photocatalysts. In this hybrid photocatalyst, the nanosized NiS on the surface can serve as electron trapping sites, by which, photogenerated electrons were extracted from Cd0.5Zn0.5S substrate, leading to spatially separated photoreduction and oxidation reactions. More interestingly, it was found that NiS played a similar role as noble metal, providing active sites for proton reduction, and hence efficiently enhancing the overall hydrogen production rate. Our work demonstrates the possibility of substitution of noble metal cocatalyst by a properly engineered surface hetero-junction to achieve efficient and low cost photocatalytic hydrogen production.

The first organic-templated Ba(II) perchlorate with open architecture, [(C6H8N)2Ba(ClO4)4]n (1), has been synthesized in the presence of 3-methylpyridine (3-MP) under hydrothermal conditions. The compound 1 was characterized by single crystal X-ray diffraction, elemental analysis, IR, powder XRD, 1H NMR, TGA and fluorescence spectra. The 12-coordinate Ba(II) ion was located in the center of the irregular icosahedral (BaO12) cage. Then the icosahedral BaO12 cages and the ClO4- linkers joined together to form a (4, 4) topology. And the protonated amine molecules were residing in the interlamellar space of the inorganic macro-anionic topology layers in the aAa mode (a = amine, A = anionic layer). The N–H⋯O hydrogen bonds ensure the stability of the structure by mounted the organic molecules to the main body of the inorganic framework. The solid-state fluorescence spectrum of complex 1 exhibits broad emission at 381 nm at room temperature, which is stronger than the free MPP (MPP = 3-methylpyridinium perchlorate). In addition, the two different synthesis methods provide an effectual impetus about applying hydrothermal reaction chemistry to build novel structures.Highlights► Complex 1 has been synthesized by performing two different methods. ► The first Ba(II) perchlorate macro-anionic inorganic-framework network. ► The protonated template molecules residing in the interlamellar space. ► Formation of (4, 4)-connected topology framework.

•SiO2-g-(PDMAEMA-co-PDMAPS) NPs were prepared via Si-ARGET ATRP.•The organic–inorganic hybrid membranes were fabricated via NIPS process.•Modified membranes exhibited enhanced water flux without any lost in oil rejection.•The M membranes showed better antifouling property than m membranes.To avoid the agglomeration of nanoparticles (NPs) in hybrid membranes and alleviate the leakage of NPs during the oily wastewater treatment process, poly(2-(dimethylamino)ethylmethacrylate-co-3-dimethyl(methacryloyloxyethyl)ammoniumpropanesulfonate) (PDMAEMA-co-PDMAPS) grafted silica (SiO2) [SiO2-g-(PDMAEMA-co-PDMAPS)] NPs were prepared by grafting PDMAEMA brushes onto SiO2 NPs surface via the surface-initiated activators regenerated by electron transfer atom transfer radical polymerization (Si-ARGET ATRP). Subsequently, the quaternization of the tertiary amine groups in PDMAEMA and 1,3-propanesultone was performed to get [SiO2-g-(PDMAEMA-co-PDMAPS)] NPs. Then, the organic–inorganic hybrid polyethersulfone (PES) membranes with different ratios of SiO2 NPs (m membranes) and SiO2-g-(PDMAEMA-co-PDMAPS) NPs (M membranes) were fabricated via the non-solvent induced phase separation (NIPS) process. Transmission electron microscopy (TEM) images demonstrated that the modification of SiO2 NPs with PDMAEMA-co-PDMAPS was favorable for their homogeneous dispersion in organic solvents. The results of scanning electron microscopy (SEM) images indicated that the surface porosity and mean pore size of hybrid membranes were increased compared to the neat PES membrane. Furthermore, the M membranes exhibited better hydrophilicity, pure water flux and oil flux than neat PES membrane and m membranes. It was found from filtration results that the total fouling (Rt) and irreversible fouling (Rir) were significantly reduced due to higher hydrophilicity of hybrid membranes. In addition, after oil-in-water emulsion filtration, M membranes exhibited higher water flux recovery ratio (FRR) value than that of m membranes and neat PES membrane.

A novel composite material, MoS2/SrTiO3, has been successfully prepared via a two-step simple hydrothermal method. The photocatalytic performance of MoS2/SrTiO3 composites in the degradation of MO organic dyes under UV-light irradiation and the effect of the loading amount of MoS2 were investigated. For the first time, it was found that the as-prepared composites showed a high degradation rate and that the photocatalytic activity over pure SrTiO3 could be significantly enhanced by loading MoS2. Importantly, there is an optimal loading amount of MoS2 on the SrTiO3 in terms of degradation rate. In addition, the MoS2/SrTiO3 composite material with 0.05 wt% of MoS2 showed the best photocatalytic activity, with a degradation rate as high as 99.81% after 60 min irradiation time. The promoting effect caused by MoS2 can be due to the suppression of recombination between electrons and holes. This study demonstrates high potential for the development of environmentally friendly, cheap non-noble metal composite materials for photocatalytic degradation.

Water produced from alkaline–surfactant–polymer flooding technology is more difficult to treat than that from water flooding. In this study, a novel magnetic demulsifier, called M-5010, was synthesized through the reaction of 5010, a type of demulsifier currently used in oilfields, and epoxy group functionalized Fe3O4@SiO2 microspheres. The oil removal rates and effect of the demulsifier dosage as well as the settling time were investigated. It was found that the oil removal rate of M-5010 was higher than that of 5010 under the same conditions. In addition, M-5010 can be recycled and reused by using an external magnetic field that acts as a material phase separator. Accordingly, we found that M-5010 is still effective after being reused for 5 cycles. Our results indicate that the magnetic demulsifier we fabricated can be used as an effective and recyclable material for the removal of oil from oil contaminated wastewater.

Nanosized photocatalysts have been shown to be important to many modern photocatalytic reactions. Control of the microstructure of the nanocrystals enables regulation of their optical properties and enhancement of specific reactions. Here, Cu2+-doped ZnS nanosphere photocatalysts with hierarchical nanostructures and controllable sizes were synthesized via a facile wet-chemical reaction. We demonstrated that small amounts of Cu2+ doping could give rise to the formation of a variety of localized, nanosized Cu1−xZnxS solid solutions that are separated by a continuous ZnS medium. The nano-solid-solutions have predictable band structures and an average size of several nanometers, which ensure facile generation of electron–hole pairs by visible light irradiation and quick migration of the photo-generated charges to the interfaces. With Ru as a cocatalyst, the as-prepared 0.5 mol% Cu2+-doped ZnS nanospheres showed a high H2 evolution rate of 1.03 mmol h−1, corresponding to a quantum efficiency of 26.2% at 425 nm. A hierarchical surface structure with a large surface area is considered crucial for the increased activity. Our work not only showed that the non-toxic metal chalcogenides achieve high efficiency but also provides a new concept of localized nano-solid-solution for photocatalytic applications.