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Ferric acetylacetonate/covalent organic framework (Fe(acac)3/COF) composite was synthesized by interfacial polymerization method at room temperature. The crystal structure, morphology and porosity property of the composite were characterized by X-ray diffraction, scanning electron microscope, transmission electron microscope and nitrogen adsorption. The interaction between Fe(acac)3 and COF was investigated by Fourier transform infrared spectra and X-ray photoelectron spectroscopy. The Fe(acac)3/COF composite was used as a photocatalyst for the oxidation of benzyl alcohol under mild conditions. It exhibits high activity and selectivity for the reaction, of which the mechanism was investigated by determining its photoelectric properties. The Fe(acac)3/COF catalyst developed in this work has application potential in other photocatalytic reactions.

Pickering emulsion is a heterogeneous system consisting of at least two immiscible liquids, which are stabilized by solid particles, in which organic solvent or water is dispersed into other phase in form of micrometre-sized droplets. Compared to traditional emulsions stabilized by surfactant, solids are cheap and can be easily separated and recycled by centrifugation or filtration after use. Moreover, the properties of Pickering emulsions can be adjusted by using different types of solid particles. Up to now, Pickering emulsions have been applied in a wide range of areas such as material science and catalysis. Here we review recent studies on Pickering emulsions stabilized by metal-organic framework, graphitic carbon nitride and graphene oxide.

Using solar energy to realize CO2 reduction and benzylamine oxidation is of great importance. Here, we design Zn-Bi2WO6 microflowers catalyst, which can simultaneously reduce CO2 to CO and oxidize benzylamine to N-benzylbenzaldimine with high activities and selectivities in a simple photocatalytic system.

Herein we propose the utilization of nanosized water domains for photocatalytic CO2 conversion, by which CO2 can be efficiently reduced to CO with a CO evolution rate of 682 μmol g−1 h−1 and selectivity >99%. It provides a facile, efficient and adjustable route for photocatalytic CO2 conversion with water.

To construct the heterojunctions of TiO2 with other compounds is of great importance for overcoming its inherent shortages and improving the visible-light photocatalytic performance. Here we propose the construction of TiO2/covalent organic framework (COF) heterojunction with tight connection by a supercritical CO2 (SC CO2) method, which helps bridging the transformation paths for photo-induced charge between TiO2 and COF. The produced TiO2/COF heterojunction performs a H2 evolution of 3,962 µmol·g−1·h−1 under visible-light irradiation, which is ∼ 25 times higher than that of pure TiO2 and 4.5 folds higher than that of TiO2/COF synthesized by the conventional solvothermal method. This study opens up new possibilities for constructing heterojunctions for solar energy utilization.

The production of 2D metal-organic frameworks (MOFs) with highly exposed active surfaces is of great importance for catalysis. Here we demonstrate the formation of MOF nanosheets by utilizing CO2 as a capping agent to control the oriented growth of MOF. This strategy has many advantages over the conventional methods. For example, it is template-free and proceeds at mild temperature (35 °C), CO2 can be easily removed by depressurization, and the properties of the MOF nanosheets can be well adjusted by changing CO2 pressure. Such a simple, rapid, efficient and adjustable route produces MOF nanosheets with ultrathin thickness (∼10 nm), small lateral size (∼100 nm) and abundant unsaturated coordination metal sites on surfaces. Owing to these unique features, the as-synthesized MOF nanosheets exhibit superior activity for catalyzing the oxidation reactions of alcohols., Producing two-dimensional metal-organic frameworks (MOFs) with highly exposed active surfaces is important for catalysis. Here, authors prepare MOF nanosheets by using CO2 as a capping agent to control the oriented growth of MOFs.

In this research, a systematic analysis and comparison between the behavior and the kinetics of coal drying in Ar, coal pyrolysis in Ar, char gasification in CO2, and char combustion in air were co...

Here, we demonstrate for the first time the construction of covalent organic framework (COF) capsules with nanostructured surfaces, which combine advantages of highly accessible surface area, excellent light absorbance, and efficient separation of photogenerated electron-hole pairs. The COF capsules exhibit high activity and selectivity for photocatalytic oxidation under mild conditions.

Novel boron-doped CuO nanobundles are designed for CO2 reduction to the single multi-carbon product of ethylene, and their faradaic efficiency can reach 58.4% with a current density of 18.2 mA cm−2. This active, selective and simply prepared electrocatalyst provides a promising electrocatalyst candidate for CO2 reduction to ethylene.

Developing a facile route for improving the photocatalytic performances of metal–organic frameworks is of great importance. Herein, we demonstrate for the first time that downsizing NH2-MIL-125 crystals to the nanometer scale can greatly improve their activity for the photocatalytic benzylamine oxidation reaction. Under mild conditions, the conversion of benzylamine into N-benzylbenzaldimine reaches 98.5% in 9 h with a turnover frequency (TOF) value of 1063 μmol g−1 h−1 as catalyzed by NH2-MIL-125 nanocrystals, much superior to NH2-MIL-125 microcrystals (conversion 55.9% and TOF 570 μmol g−1 h−1, respectively). The as-synthesized NH2-MIL-125 nanocrystals have a small crystal size, abundant oxygen vacancies, enhanced light absorption ability, strong oxygen reduction capacity, strengthened separation capability and transfer efficiency of photoexcited charges, conferring them high photocatalytic performance for the benzylamine oxidation reaction.

Multi-component photocatalysts can take advantage of each component and overcome their shortcomings at the same time by synergetic effect, providing a great promising future for high activity photocatalyst. In this work, P3HT/Ag/TiO2 ternary photocatalyst was constructed to further promote the separation of photogenerated carriers and enhance the photocatalytic activity as much as possible by introduction of Ag nanoparticles into the conjugated polymers/TiO2 heterojunction. The results showed that different amount of Ag nanoparticles were successfully photodeposited on the surface of TiO2 to form Ag/TiO2 composites, which were subsequently hybridized with P3HT, obtaining P3HT/Ag/TiO2 ternary photocatalytic system. The ternary photocatalyst exhibit remarkably enhanced photocatalytic activity for degradation of MO compared to the single- and two- component systems under both visible light and ultraviolet illumination by varying Ag content. This should be ascribed to the favored separation of photogenerated carriers resulted from the synergistic effect of P3HT, Ag and TiO2, as confirmed by the results of photocurrent tests. However, the influence of Ag content on photocatalytic activity under various light conditions was totally different. P3HT/Ag/TiO2-1, with a very small amount of Ag, showed the highest visible light photocatalytic activity, which was 2.1 and 9.7 times that of P3HT/TiO2 and TiO2 respectively and then the photocatalytic activity decreased with Ag loading amount. For the photocatalytic experiments performed under ultraviolet light, the activity continuously increased with the Ag content within our conditions, reaching the maximum for P3HT/Ag/TiO2-4, which was 4.5 and 1.8 times that of P3HT/TiO2 and Ag/TiO2-4 respectively. This might be resulted from the different role of Ag nanoparticles, probably electron sink under visible irradiation and Z-scheme bridge between P3HT and TiO2 under ultraviolet light.

To well understand the effect of char property on tar catalytic reforming and support the development of two-stage gasification technology for the clean fuel gas production, the roles of pore structure and metal oxide in tar removal behavior were examined and compared on a fluidized bed two-stage reactor. The results show that although both of micro pore and meso pore had a remarkable influence on tar removal efficiency, fuel gas component and distilling fractions in tar, perhaps micro pore played a much more important role. Moreover, the tar removal efficiency did not have a good proportional relationship with the specific surface area of char. For the spent char, the activation treatment in steam was very beneficial to renew the catalytic reforming on tar by increasing the surface area of micro pore and maintain its high gasification activity. Compared to the demineralized char, the char samples that loaded metal oxide by impregnation approach largely promoted the tar removal efficiency, following the rank of Na2O > Fe2O3 > CaO > MgO. For Na2O, it not only had the best catalytic activity on tar, but also greatly promoted the generations of light tar and effective fuel gas, such as H2 and CO. Finally, considering the different effect of pore structure and metal oxide on tar catalytic reforming, a brief mechanism of tar catalytic reforming by char was proposed.

It is of great importance to develop facile strategies to synthesize catalysts with desirable compositions and structures for high-performance photocatalytic hydrogen generation. In this work, we put forward an ionic liquid assisted one-pot route for the synthesis of heteroatom-doped Pt/TiO2 composite material. This route is simple, environmentally benign and adjustable owing to the designable properties of ionic liquids. The as-synthesized Pt/TiO2 nanocrystals exhibit high activity and stability for the photocatalytic hydrogen generation under simulated solar irradiation. This method can be easily applied to the synthesis of various kinds of metal/TiO2 composites doped with desirable heteroatoms (e.g., F, Cl, Br, etc).

Developing highly efficient electrocatalysts based on cheap and earth-abundant metals for CO2 reduction is of great importance. Here we demonstrate that the electrocatalytic activity of manganese-based heterogeneous catalyst can be significantly improved through halogen and nitrogen dual-coordination to modulate the electronic structure of manganese atom. Such an electrocatalyst for CO2 reduction exhibits a maximum CO faradaic efficiency of 97% and high current density of ~10 mA cm−2 at a low overpotential of 0.49 V. Moreover, the turnover frequency can reach 38347 h−1 at overpotential of 0.49 V, which is the highest among the reported heterogeneous electrocatalysts for CO2 reduction. In situ X-ray absorption experiment and density-functional theory calculation reveal the modified electronic structure of the active manganese site, on which the free energy barrier for intermediate formation is greatly reduced, thus resulting in a great improvement of CO2 reduction performance., While renewable CO2 conversion provides a means to remove and recycle waste emissions, there are few earth-abundant materials that are both efficient and active. Here, authors prepare N-doped carbon with atomic manganese as high-performance CO2 reduction electrocatalyst.

The utilization of water and carbon dioxide, which are the most abundant solvents on earth, is of great importance. Carbon dioxide is readily available, inexpensive, nontoxic, nonflammable, has moderate critical temperature and pressure (31.1 °C and 7.38 MPa), and can be easily recaptured and recycled after use, offering many advantages to replace conventional organic solvents. However, carbon dioxide is often a poor solvent because it has no dipole moment, very low dielectric constant and polarizability per volume, which restrict its applications in various fields. To combine carbon dioxide with water will largely expand the utilities of these two solvents. The properties of water/carbon dioxide systems and their applications in material synthesis and chemical reaction are reviewed.

The application of metal–organic frameworks (MOFs) in catalysis is largely restricted by their intrinsic properties, thus the development of modified MOFs is promising for improving the activities....

The application of nickel in electrocatalytic reduction of CO2 has been largely restricted by side reaction (hydrogen evolution reaction) and catalyst poisoning. Here we report a new strategy to improve the electrocatalytic performance of nickel for CO2 reduction by employing a nitrogen-carbon layer for nickel nanoparticles. Such a nickel electrocatalyst exhibits high Faradaic efficiency 97.5% at relatively low potential of -0.61 V for the conversion of CO2 to CO. Density functional theory calculation reveals that it is thermodynamically accomplishable for the reduction product CO to be removed from the catalyst surface, thus avoiding catalyst poisoning. Also, the catalyst renders hydrogen evolution reaction to be suppressed and hence reasonably improves catalytic performance.

Ultrathin metal–organic framework (MOF) nanosheets were fabricated by a surfactant-mediated coordination strategy through a pseudo-assembly process. The thickness of the nanosheets could be tuned from 3 nm to 60 nm by varying the hydrophobic chain length of the surfactant. Ru nanoparticles supported on the nanosheets exhibited superior catalytic activity for hydrogenation of levulinic acid to γ-valerolactone.

The electrocatalytic conversion of CO2 to CO using non-noble metal catalysts under mild conditions is of great importance. Achieving the combination of high activity, selectivity and current density by developing electrocatalysts with desirable compositions and structures is challenging. Here we prepared for the first time CuxNiy alloy nanoparticles embedded in a nitrogen–carbon network. Such an electrocatalyst not only well overcomes the disadvantages of single Cu and Ni catalysts but has a high CO2 adsorption capacity. Outstandingly, the catalyst can effectively convert CO2 into CO with a maximum faradaic efficiency of 94.5% and current density of 18.8 mA cm−2 at a low applied potential of −0.60 V (versus reversible hydrogen electrode, RHE). Moreover, the catalyst is very stable during long-term electrolysis owing to the stabilization of the nitrogen–carbon network.

In this study, we synthesized an efficient catalyst of NH2-MIL-125 (Ti)/Pt/g-C3N4 composites for the visible-light-driven H2 production reaction. Compared with Pt/g-C3N4, the as-synthesized NH2-MIL-125 (Ti)/Pt/g-C3N4 composites show greatly improved performance for photocatalytic H2 production. The highest H2 production rate of the NH2-MIL-125 (Ti)/Pt/g-C3N4 catalyst was found to be 3986 μmol h−1 g−1, which is much higher than that of Pt/g-C3N4 (1100 μmol h−1 g−1) under the same experimental conditions. The NH2-MIL-125 (Ti)/Pt/g-C3N4 catalyst has application potential for other photocatalytic reactions.

With respect to the newly proposed fluidized bed two-stage (FBTS) gasification process, the researches on tar thermal cracking and catalytic removal by char bed layer were conducted on a FB two-stage reaction apparatus. It shows that the effect of char on tar removal was much related to the reaction temperature and residence time of tar-containing fuel gas in the tar reformer. Under the tested experimental conditions, increasing reaction temperature and residence time can effectively promote tar abatement and generate more H2, CO and CH4. For catalytic reforming by char, the higher reaction temperature and the longer residence time, the lower tar content in fuel gas. Compared to thermal cracking, catalytic reforming of tar by char was more effective in tar removal efficiency and inhibition of carbon deposition, upgrading the quality of fuel gas. The researches indicated that the suitable operational conditions for tar removal by char in the FB two-stage gasification process were at reforming temperature of 1000 °C, and residence time above 0.9 s.

Electrochemical reduction of CO2 to CH3 OH is of great interest. Aerogels have fine inorganic superstructure with high porosity and are known to be exceptional materials. Now a Pd-Cu bimetallic aerogel electrocatalyst has been developed for conversion of CO2 into CH3 OH. The current density and Faradaic efficiency of CH3 OH can be as high as 31.8 mA cm-2 and 80.0 % over the Pd83 Cu17 aerogel at a very low overpotential (0.24 V). The superior performance of the electrocatalyst results from efficient adsorption and stabilization of the CO2 radical anion, high Pd0 /PdII and CuI +Cu0 /CuII ratios, and sufficient Pd/Cu grain boundaries of aerogel nanochains.

The development of facile, rapid, low-energy, environmentally benign routes for the synthesis of covalent organic frameworks (COFs) is of great interest. This study concerns the utilization of water containing dissolved CO2 as a solvent for the room-temperature synthesis of COF. The as-synthesized particles, denoted COF-LZU1, combine advantages of good crystallinity, nanoscale size, and high surface area, which suggests promising application as a support for heterogeneous catalysts. Moreover, this versatile CO2 -assisted method is also applicable for the room-temperature synthesis of Cu-COF-LZU1. This method gives rise to new opportunities for fabricating COFs and COF-based materials with different compositions and structures.

To develop photocatalysts with desirable compositions and structures for improving the efficiency and selectivity of CO2 conversion to CH4 under mild conditions is of great importance. Here, we design an effective photocatalyst of bimetal (Ag/Pd) nanoalloys supported on nitrogen-doped TiO2 nanosheet for CO2 conversion. Such a novel photocatalyst combines multiple advantages of abundant Ti3+ ions, oxygen vacancies, and substitutional nitrogen that are favorable for catalyzing CO2 reduction. It was found that CO2 could be efficiently transformed to CH4 under mild conditions, i.e., in aqueous solution and at atmospheric pressure and room temperature. The maximum production rate of CH4 can reach 79.0 μmol g–1 h–1. Moreover, the Ag/Pd bimetals supported on N-doped TiO2 nanosheet exhibit high selectivity to CH4. The as-synthesized photocatalyst can be well recycled for CO2 reduction.

Aiming at developing highly efficient photocatalysts by broadening the light-harvesting region and suppressing photo-generated electron-hole recombination simultaneously, this work reports rational design and fabrication of donor-acceptor (D-A) conjugated polymer/TiO2 heterojunction catalyst with strong interfacial interactions by a facile in-situ thermal treatment. To expand the light-harvesting window, soluable conjugated copolymers with D-A architecture are prepared by Pd-mediated polycondensation of diketopyrrolopyrrole (DPP) and t-butoxycarbonyl (t-Boc) modified carbazole (Car), and used as visible-light-harvesting antenna to couple with TiO2 nanocrystals. The DPP-Car/TiO2 composites show wide range absorption in 300–1000 nm. To improve the interfacial binding at the interface, a facile in-situ thermal treatment is carried out to cleave the pendant t-Boc groups in carbazole units and liberate the polar amino groups (–NH–) which strongly bind to the surface of TiO2 through dipole–dipole interactions, forming a heterojunction interface. This in-situ thermal treatment changes the surface elemental distribution of TiO2, reinforces the interface bonding at the boundary of conjugated polymers/TiO2 and finally improves the photocatalytic efficiency of DPP-Car/TiO2 under visible-light irradiation. The interface changes are characterized and verified through Fourier-transform infrared spectroscopy (FT-IR), photo images, UV/Vis (solution state and powder diffuse reflection spectroscopy), X-ray powder diffraction (XRD), X-ray photoelectron spectroscopy (XPS), fluorescence, scanning electron microscopy(SEM) and transmission electron microscopy (TEM) techniques. This study provides a new strategy to avoid the low solubility of D-A conjugated polymers and construct highly-efficient conjugated polymer/TiO2 heterojunction by enforcing the interface contact and facilitating charge or energy transfer for the applications in photocatalysis.

Developing hybrid carbon materials with unique micro-/nano-structured and multicomponent features is of great importance in catalysis, energy storage and conversion. Herein, we demonstrate the formation of a novel kind of hybrid carbon material, i.e., the bimetallic nanoparticles are supported by ultrathin (~5.5 nm) and porous carbon nanosheets, by the pyrolysis of pre-formed bimetallic metal-organic framework nanosheets. This hybrid carbon nanostructure combines the advantages of highly exposed nanoparticles that are easily accessible to reactant, multiple active sites like metal-metal, metal-nitrogen and ultrathin carbon layers and highly efficient electron transport. Owing to these unique features, the bimetallic carbon nanosheets exhibit excellent electrocatalytic performance for oxygen reduction reaction.

Here we report the first synthesis of nearly pure-phase Cu3Si alloy that can be a highly efficient catalyst in the hydrochlorination of silicon reaction. This material was prepared by a high-temperature (1050 ​°C) calcination method in which copper and silicon powders were used as the reactants. The X-ray photoelectron spectroscopy (XPS) study revealed that the Cu and Si atoms in the Cu3Si alloy carried part of positive and negative charge, respectively. When employed as the catalyst in the silicon hydrochlorination to SiHCl3 (TCS) for the production of Si polycrystals for Solar cell, the sample Cu3Si exhibited excellent low-temperature catalytic performance: the Si conversion and TCS selectivity respectively achieved 41.1% and 96.1% at 250 ​°C. Notably, its TCS yield at 250 ​°C was 1.2 times higher than that of the industrial catalyst-free system at 350 ​°C. Detailed analysis of the reaction process showed that the positively charged Cu atoms and negatively charged Si atoms in Cu3Si alloy could cleave the H–Cl bond in the reactant HCl and make the combination of H and Cl atom with Si atoms easier. Meanwhile, the reaction between the remaining Cu atom and Si was accelerated, leading to the generation of more active Cu6.69Si and ultimately superior catalytic performance. This work deepens the fundamental understanding of the hydrochlorination of silicon reaction, and provides an avenue for the synthesis of Si-based alloy catalysts.

Here we propose the emulsification of CO2 and water with graphitic carbon nitride (g-C3N4), in which the g-C3N4-stabilized CO2 droplets were utilized as “microreactors” for in situ photocatalytic CO2 reduction. The g-C3N4 sheets assembling at the CO2/water interface can serve both as an emulsifier and photocatalyst, which can greatly promote the conversion of CO2 to formic acid.

Herein, we demonstrate for the first time the one-step synthesis of ultrathin α-Co(OH)2 nanomeshes by an imidazole-directed route. The α-Co(OH)2 nanomeshes combine the advantages of ultrathin thickness (3 nm), small mesopores (3.7 nm), large specific surface area (181.1 m2 g−1) and high surface oxygen vacancy density, which exhibit excellent electrocatalytic performance for the oxygen evolution reaction.

Efficient and durable thermal insulators combined with flame resistance are required for energy efficient buildings. Here, we fabricate poly(p-phenylene benzobisoxazole) (PBO) nanofiber aerogels (PBOAs) through a proton-consumption-induced gelation of PBO nanofiber sol and a controlled freeze-drying with a low cooling rate, followed by thermal cross-linking. Nanofibrous networks based on physical entanglement of nanofibers and chemical cross-linking at the junctions were obtained, leading to ultralow density (3.6–15.7 mg cm−3), high porosity (98.9–99.7%), high specific surface area (155.4 m2 g−1), low thermal conductivity (26.2–37.7 mW m−1 K−1) and superelasticity under an ultimate strain of 99%. More importantly, the aerogels achieve an excellent thermal stability, including a high decomposition temperature of 650 °C and a high long-term use temperature of 350 °C. Furthermore, the PBOAs are characterized by outstanding flame resistance, reach the nonflammable level in vertical burning tests (UL-94, V-0 class), and show a limiting oxygen index (LOI) as high as 52.8%. The aerogels cannot be ignited under simulated real-scale fire conditions, leaving suppressed smoke emission and reduced potential for flame spread and fire hazards. High thermal insulation and resistance to a 1000 °C flame has been achieved by compositing PBOAs with fumed silica. Thus, the PBOAs have promising applications in energy efficient areas, such as buildings, aerospace and many other fields, especially under harsh conditions.

Highly selective production of valuable hydrocarbons from CO2 electroreduction is particularly desirable yet challenging. Herein we steer CO2 electroreduction toward methane (CH4) or ethylene (C2H4) production with high selectivity by controlling the loading of copper phosphate (Cu3(PO4)2) nanosheets on electrode. The low loading (0.28 mg cm-2) and high loading (2.24 mg cm-2) of Cu3(PO4)2 nanosheets lead to Faradaic efficiency of 76% for CH4 and 67% for C2H4, respectively. Mechanism investigation reveals that metallic Cu nanoparticles are derived during electrolysis at low Cu3(PO4)2 loading condition, favoring *CO hydrogenation to CH4 production. At high Cu3(PO4)2 loading condition, the metallic Cu nanoparticles decorated with Cu3(PO4)2 are produced, which can stabilize and promote the dimerization of *CO to C2H4 formation. This work provides new insights into controlling the electrocatalytic CO2 reduction from C1 to C2 products by designing derivatives of Cu-based catalyst.

Developing Ni-based catalysts with high activity and stability in low-temperature methanation is necessary due to their sintering and coking at high temperatures. Here, we report our developed novel Ni-Zr-Al catalysts derived from Ni-Zr-Al ternary hydrotalcites synthesized by a hydrothermal process, followed by a reduction in hydrogen. Comparing with the Ni-Al catalyst derived from Ni-Al hydrotalcite and the commercial Ni-based catalyst, the Ni-Zr-Al catalysts show a remarkably higher low-temperature activity (210−270 °C) in CO2 methanation. Both the experimental and theoretical calculations confirmed the introduction of Zr into the Ni-Al binary hydrotalcite could generate synergetic effects between Ni and ZrO2, resulting in more surface oxygen vacancies, basic sites, and abundant mesopores. In-situ DRIFTS analysis showed the CO2 methanation to CH4 follows the intermediate formate route. This work provides a new theoretical understanding of CO2 activation and methanation, and a practical way to address the existing problem for Ni-based catalysts.

The metal-organic framework (MOF) is utilized as functional additive in non-perfluorinated polymer membrane for vanadium flow battery (VFB) application for the first time. The UiO-66 series can be easily modified to form suitable pore size distribution and are robust toward aqueous and acidic conditions. Owing to the different stokes radius of protons and vanadium ions, the additive micoporous UiO-66 series increase membranes’ proton selectivity effectively. Outstandingly, the VFBs with MOF-loaded polymer membranes exhibit higher coulombic efficiency and energy efficiency than those using neat polymer membrane and the perfluorinated Nafion 115 membrane at the same conditions. Moreover, the blend membranes present ultra-long self-discharge time up to 200 h and stable performance for 100 charge-discharge cycles without significant decline in energy efficiency. The MOF-loaded polymer membranes are promising for VFB applications due to the high efficiency, excellent stability, low cost and easy designation and functionality.

Here, we propose a CO2/water interfacial route for photocatalytic CO2 conversion by utilizing a metal–organic framework (MOF) as both an emulsifier and a catalyst. The CO2 reduction occurring at the CO2/water interface produces formate with remarkably enhanced efficiency as compared with that in conventional solvent. The route is efficient, facile, adjustable, and environmentally benign, which is applicable for the CO2 transformation photocatalyzed by different kinds of MOFs.

Using functional materials to stabilize emulsions of carbon dioxide (CO2) and water is a promising way to expand the utility of CO2 and functional materials. Here we demonstrate for the first time that the partially reduced graphene oxide (rGO) can well stabilize the emulsion of CO2 and water without the aid of any additional emulsifier or surface modification for rGO. More interestingly, such a novel kind of emulsion provides a facile and versatile route for constructing highly porous three-dimensional rGO materials, including rGO, metal/rGO, and metal oxide/rGO networks. The as-synthesized Au/rGO composite is highly active in catalyzing 4-nitrophenol reduction and styrene epoxidation.

Metal-organic frameworks (MOFs) have attracted increased research attention in photocatalysis due to their great potential in light harvest and conversion. However, the organic transformations as photocatalyzed by MOFs under mild conditions yet remain a challenge. Herein, three bipyridyl-containing cadmium-organic frameworks Cd(dcbpy) (dcbpy = 2,2'-bipyridine-5,5'-dicarboxylate), Cd(bdc)(bpy) (bdc = 1,4-benzenedicarboxylate; bpy = 2,2'-bipyridyl), and Cd(bdc)(2Me-bpy) (2Me-bpy = 4,4'-dimethyl-2,2'-bipyridyl) were synthesized for the first time. The bpy-containing Cd-MOFs have strong light harvest abilities and suitable photocatalysis energy potentials, making them highly active and selective for the photo-oxidation of benzylamine to N-benzylbenzaldimine under mild conditions, i.e., using atmospheric air as oxidant, at room temperature, and in the absence of any photosensitizer or cocatalyst. It provides an efficient, economical, and green way for the direct oxidation of amines to produce imines.

Herein we propose an interfacial assembly and hydrolysis route for fabricating TiO2/UiO-67 composites. The UiO-67 assembles at the water–oil interface serving as a stabilizer of the emulsion. TiO2 nanoparticles are loaded on UiO-67 by hydrolysis of the precursor TBT (tetra-n-butyl titanate) at the water–oil interface. By such a strategy, hollow capsules structured by UiO-67 and decorated by ultra-small TiO2 nanoparticles were produced. The newly-constructed composite combines the CO2 adsorption properties of UiO-67 and the photocatalytic activity of TiO2, showing high activity for the photocatalytic reduction of CO2 to formic acid. Such a composite with a novel structure provides a promising route for the preparation of new compound materials.

Forming emulsions of carbon dioxide (CO2 ) and water can largely expand the utility of CO2 . Herein we propose for the first time the utilization of a metal-organic framework (MOF) for emulsifying CO2 and water. Owing to the hybrid composition, MOF particles can easily assemble at the CO2 /water interface to create a rigid protective barrier around the dispersed droplet. The MOF-stabilized CO2 and water emulsion has exceptional stability compared to those emulsions stabilized by surfactants or other solids. Moreover, the CO2 and water emulsion stabilized by MOF is "tunable" due to the designable features of MOFs and adjustable character of CO2 . Such a novel kind of emulsion composed of CO2 , water, and MOF provides a facile route for constructing MOF superstructures with many advantages. The macroporous networks and hollow capsules of different kinds of MOFs have been successfully derived from CO2 and water emulsions.

Structural engineering of two-dimensional (2D) materials has attracted intensive interests for promoting the performances in energy storage and catalysis. Herein, we demonstrate for the first time the construction of BiOCl nanosheets with periodic nanochannels by a wet chemical route. Such a structure induces the shortened Bi–O bonds in BiOCl crystal, which enhances the localized charge density near the valence and conduction band edge. Thus, the Coulomb interactions between photogenerated electrons and holes are strengthened in BiOCl, which promotes the robust exciton effect for high-efficiency formation of singlet oxygen in photooxidation. It is remarkable that the BiOCl nanosheets with periodic nanochannels deliver 30-fold enhanced photooxidation performance for the coupling of benzylamine than the ordinary BiOCl nanosheets. This work not only paves a new approach for creating upgraded 2D structure, but also provides a new insight in controlling photogenerated charge carriers by nanostructure engineering.

Electrochemical reduction of carbon dioxide (CO2) is a potentially useful step in energy storage and greenhouse gas alleviation. Here we demonstrate for the first time a Fe-N4O-doped nanoporous carbon as robust electrocatalyst for CO2 reduction, where the five-coordinated Fe-N4O structure works as catalytically active site. It exhibits a high faradaic efficiency of 96 % towards CO with partial current density of -5.4 mA cm−2 at low overpotential of 470 mV. First-principles density functional theory calculations reveal that the free energy barrier for *CO desorption is greatly reduced on Fe-N4O site compared to Fe-N4, resulting in a higher selectivity to CO for a wider electrochemical window. This work opens up new possibilities for improving the catalytic performance of metal-N-C electrocatalysts by regulating the co-ordination of metal atom.

In the present research, a concept of fluidized bed two-stage gasification has been proposed to gasify the wet industrial biomass, which decouples the direct gasification of biomass into the main sub-processes of drying, pyrolysis, gasification, and combustion. To better understand the reaction behavior and kinetics of these main sub-processes, a micro fluidized bed reaction analyzer was adopted. Moreover, a kind of water-adsorbing char was chosen to simulate the drying behavior of wet biomass. In the examined temperature range of 1123–1223 K, the processes of pyrolysis and combustion were conducted in the second scale, while that of gasification and drying was in the minute level, dominating the whole gasification process. For the reaction rate, at above 1173 K, they followed the order of pyrolysis > combustion > gasification > drying. The volume reaction model and shrinking core reaction model can be used to describe the process of pyrolysis/gasification and drying/combustion, respectively. For pyrolysis, combustion, drying, and gasification, the calculated activation energies were about 29.51, 62.39, 83.75, 210.23 kJ/mol, respectively. Finally, a schematic diagram of the FBTS gasification process was proposed for treating the wet Chinese distilled grains according to the reaction behavior and kinetics.

The hierarchical porous metal oxide combines the advantages of each class of hierarchical pores and has potential applications in different fields. Here we proposed an emulsion-calcination route for producing porous metal oxide. The porous metal-organic complex was first synthesized in CO2-in-water emulsion, then the metal-organic complex was calcined to remove the organic linker and form porous metal oxide. The hierarchical macro- and mesoporous assemblies of Co3O4 nanoparticles were produced. The hierarchical macro- and mesoporous assemblies of Co3O4 nanoparticles were produced, with the macropores in size of hundreds of nanometers and the mesopores in 9-15 nm. The porosity properties and nanoparticle size of Co3O4 can be modulated by controlling CO2 pressure. The as-synthesized Co3O4 is an excellent candidate catalyst for the methylene blue degradation. By taking advantages of the high porosity and small particle size, the Co3O4 have potential applications in catalysis, gas separation, and controlled drug release. The strategy proposed in this work can be applied to the synthesis of different kinds of porous metal oxides. (C) 2015 Elsevier Inc. All rights reserved.

Conjugated polymer/TiO2 composites are promising visible light photocatalysts for solar chemical conversion processes in the field of environmental chemistry for decomposition of organic compounds in water and air. In consideration of the fact that conjugated polymers are also organic substances, particular attention must be focused on the stability of conjugated polymer/TiO2 composites, which has not been laid enough emphasis upon so far. Poly(3-hexylthiophene)/titanium dioxide (P3HT/TiO2) composites, as a representative of conjugated polymer/TiO2 photocatalysts, were prepared by combining chemical oxidative polymerization method and physical blending technique. The stability of the composites was systematically studied by comparative analysis of the physical and chemical structure of P3HT/TiO2 composites before and after the photocatalytic reaction. As confirmed by the results of high-resolution transmission electron microscopy (HRTEM), scanning electron microscope (SEM), ultraviolet-visible diffuse reflectance spectroscopy (UV–vis DRS), Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS), the P3HT/TiO2 composites were quite stable to 10 h of photodegradation of methyl orange (MO) under visible light, maintaining both their physical and chemical structure.

Conjugated polymer/TiO2 photocatalysts hold great promise for solar chemical conversion processes by combining the advantages from both the conjugated polymer and the inorganic semiconductor, overcoming the serious drawbacks of fast charge recombination and the limited visible light absorption of inorganic semiconductor through interfacial electron transfer. To address the crucial way to promote the visible light photocatalytic activity of conjugated polymers/TiO2 photocatalysts, P3HT/TiO2 composites with strong interfacial interaction between P3HT and TiO2, which was demonstrated by the results of X-ray photoelectron spectroscopy and dissolution tests, were prepared by binding cyanoacrylic acid end-groups functionalized P3HT to the surface of TiO2. The pseudo-first-order kinetic constants of photocatalytic degradation of model pollutant methyl orange (MO) under visible light with P3HT/TiO2 composites of monofunctionalized and difunctionalized polymers were 7.06 and 20.18 times as great as that of unfunctionalized polymer, respectively, indicating a remarkably enhanced visible light photocatalytic activities by an order of magnitude with the incorporation of cyanoarrylic acid end-groups. In consideration of their similar morphology, specific surface area, ability of harvesting visible light and adsorption capacities toward MO independent of end-group functionalization, the dramatically enhanced photocatalytic activity arises from the facilitated electron injection and separation of photogenerated carriers owing to strong interfacial interaction between TiO2 and end-group functionalized P3HT, which was proved to be crucial for photocatalytic capability of conjugated polymer/TiO2 photocatalysts, providing a new effective direction for the improvement of their visible light photocatalytic activity.

Polypyrrole/polyvinyl alcohol–titanium dioxide (PPy/PVA–TiO 2 ) composite films used as photo-catalysts were fabricated by combining TiO 2 sol with PPy/PVA solution in which PPy was synthesized by in situ polymerization of pyrrole (Py) in polyvinyl alcohol (PVA) matrix and loaded on glass. The prepared photo-catalysts were investigated by X-ray diffraction (XRD), ultraviolet–visible diffuse reflection spectroscopy (UV–vis DRS), scanning electron microscopy (SEM), Fourier transform infrared (FT-IR) spectra and photoluminescence (PL). The results indicate that the composites have same crystal structure as the TiO 2 and extend the optic absorption from UV region to visible light region. By detecting the variation ratio, detected by ultraviolet–vis spectroscopy, of model pollutant rhodamine B (RhB) solution in the presence of the composite films under both UV and visible light irradiation, the photo-catalytic performance of the composite films was investigated. The results show that the PPy/PVA–TiO 2 composite films show better photo-catalytic properties than TiO 2 film both under UV and visible light irradiation, and the photo-catalytic degradation of RhB follows the first-order kinetics. The effects of the composition of composite films and the concentration of RhB on the photo-catalytic performance, as well as the possible photo-catalytic mechanism, were also discussed. By photo-catalytic recycle experiments, the structure stability of the PPy/PVA–TiO 2 composite film was investigated and the results show that the photo-catalytic activity under both UV and visible light irradiation have no significant decrease after four times of recycle experiments, suggesting that the photo-catalyst film is stable during the photo-catalytic process, which was also confirmed by the XRD pattern and FT-IR spectra of the composite film before and after photo-catalytic.

In this article, a novel visible light (VL) active photo-catalyst, calcinated-poly (vinyl alcohol) (C-PVA)/TiO 2 composites, was prepared by calcinating the films on glass substrates obtained from TiO 2 sol and initially thermally treated PVA solution. The results showed that the C-PVA with conjugated C=C bonds was doped onto the surface of TiO 2 and expanded the photo-response from ultraviolet spectrum of the TiO 2 to VL spectrum of the composites; meanwhile, the photo-luminescence of C-PVA was quenched by TiO 2 , indicating charge transfer between C-PVA and TiO 2 . The C-PVA/TiO 2 composites showed improved adsorption and photo-catalytic performances toward rhodamine B (RhB) compared to TiO 2 . When the mass feed ratio (P/T) of polymer (P) to TiO 2 (T) increased from 1:10 to 1:2, the equilibrium adsorption ratio of C-PVA/TiO 2 composites toward RhB continuously increased from 8.2 to 21.6%; while the VL photo-degradation ratio of RhB increased at first, achieving maximum value (92.2%) at P/T = 1:6, and then decreased consecutively. SEM images showed that there were lots of aggregates of TiO 2 and C-PVA on the surface of the composites. Moreover, the morphologies of those aggregates were related to the value of P/T, and the dispersion of TiO 2 in the C-PVA matrix was best while P/T = 1:6. The photo-catalytic activity of C-PVA/TiO 2 composites was closely correlated to aggregate states of C-PVA and TiO 2 , while the adsorption performance was contributed to the exposed C-PVA on the surface of C-PVA/TiO 2 composites.

Herein it was found that gas can be utilized as an activator to promote metal-organic framework (MOF) crystallization in IL at room temperature. The ultra-small MOF nanoparticles were obtained, and their size and porosity properties can be easily modulated by controlling gas pressure. The as-synthesized nano-sized Cu-MOF is an excellent candidate catalyst for the solvent-free oxidation of cyclohexene with oxygen.

CuO nanoleaves with a mesoporous structure were formed in an aqueous solution of triethylamine at room temperature. The growth process of the CuO nanoleaves in a triethylamine solution was investigated by varying the reaction time. It is shown that the CuO nanostructures form by reconstructive transformation from Cu(OH)2, going through a 0D nanoparticle → 1D nanowire → 2D nanoleaf dimensional transition process. The mechanism for the amine-induced formation of CuO at room temperature was studied by using different aliphatic amines. It is revealed that the amines play multiple roles on CuO formation, i.e. acting as an alkali, dominating the Cu(OH)2 to CuO transformation, and directing the oriented crystal growth of CuO. This route is simple, rapid, involves no additional alkalis or directing agents, and can proceed at room temperature. The as synthesized CuO exhibits excellent catalytic activity for cyclohexene oxidation with oxygen under solvent-free conditions.