Visible light mediated photoredox arylations can proceed under very mild conditions and have therefore become attractive. Nowadays, various metal nanomaterials and metal complexes have been developed as photocatalysts for direct arylation of heteroaromatics. These photocatalysts, however, still suffer from corrosion, high cost, aggregation or poor stability. We report the design and fabrication of a g-C3N4/rGO nanocomposite and demonstrate its excellent activity, high apparent quantum efficiency, and recyclability to catalyze the metal free direct arylation of heteroaromatics under visible light at room temperature. Moreover, the g-C3N4/rGO catalyst can be reused more than five times without significant loss of activity, confirming this catalyst's excellent stability. The present strategy to fabricate a metal-free g-C3N4/rGO nanocomposite for direct C–H arylation open a new avenue towards replacing metal-based catalysts in fine organic synthesis.

Nowadays, the development of a multifunction system for the simultaneous multiple signal amplification detection and fast removal of Hg2+ remains a major challenge. Herein, we for the first time used gold nanoparticles (Au NPs) and the corresponding filter membrane as chemosensors and adsorbents for dual signal amplification detection and fast removal of Hg2+. Such a system was based on the formation of gold amalgam and a gold amalgam-based reaction between rhodamine B (RhB) and NaBH4 with fluorescence and colorimetric sensing functions. When the gold amalgam catalyzes the reduction of RhB, the red color and orange fluorescence of RhB gradually changed to colorless by switching the amount of Hg2+ deposited on 13 nm Au NPs. The detection limit of the fluorescence assay and colorimetric assay is 1.16 nM and 2.54 nM for Hg2+, respectively. Interestingly, the color and fluorescence of RhB could be recovered when the above colorless reaction solution was exposed to air for about 2 hours. Taking advantage of the above optical phenomenon, a recyclable paper-based sensor has been developed by immobilizing the Au NPs and RhB dye on filter paper and has been successfully used for detection of Hg2+ in real water samples. In addition, the filter membrane immobilized Au NPs could allow fast removal of mercury ions in Yellow river water and tap water with the removal efficiency close to 99%.

A series of aza-crown ether ionic liquids supported on magnetic Fe3O4@SiO2 core–shell particles were designed, synthesized and characterized by elemental analysis, TEM, TG and FT-IR. These new aza-crown ether complex cation ionic liquids were utilized as heterogeneous acidic catalysts in Friedel–Crafts alkylation and Hantzsch reaction in good yields under convenient reaction conditions. Moreover, these magnetic particle supported IL catalysts could be readily recovered by an external magnet and reused five times without obvious loss of activity.

•The novel coumarin-derived chemosensor L is simple to synthesize.•The structure of the chemosensor L was confirmed by single crystal X-ray diffraction.•The chemosensor L can be used to determine Cu2+ ion with high selectivity can be used for imaging the Cu2+ ion in cells.•The fluorescence turn on–off mechanism and coordination mode were studied by DFT calculations.A novel coumarin-based fluorescent probe L ((4E)-4-((7-hydroxy-4-methyl-2-oxo-2H-chromen-8-yl) methyleneamino)-1,2-dihyydro-2,3-dimethyl-1-phenylpyrazol-5-one) has been developed as a simple and efficient chemosensor which exhibits a significant fluorescence reduction in the presence of metal cations. This sensor exhibits high selectivity and sensitivity toward Cu2+ over other common cations. The mechanism for detecting copper was evaluated by time-dependent density functional theory (TD-DFT) calculations and the coordination mode was also confirmed by density functional theory (DFT) calculations. Furthermore, results of cell imaging in this study indicate that this new probe may be useful for detection and monitoring of Cu2+ in biological applications.Chemosensor L was reported as a fluorescence probe for Cu2+, it exhibited high selectivity and sensitivity toward Cu2+ over other co-existed cations.

A novel, “wet” and “clean” methodology was developed to prepare FexCo100−x nanoparticles on reduced graphene oxide (RGO) surfaces in an aqueous solution through a coreduction process. Without any surface treatment, FexCo100−x nanoparticles can in situ grow on the RGO sheets. It was found that RGO nanosheets can effectively prevent the aggregation of FexCo100−x nanoparticles. The results reveal that the RGO/FexCo100−x nanocomposites have ferromagnetic characteristics and show composition dependent magnetic properties. The effectiveness of the as-prepared RGO/FexCo100−x nanocomposites as solid phase heterogeneous catalysts have been evaluated, for the first time, on the well-known 4-nitrophenol (4-NP) reduction to 4-aminophenol (4-AP) in the presence of excess sodium borohydride. The effect of initial 4-NP concentration, and catalyst loading dose were evaluated. The catalyst efficiency was examined on the basis of turnover frequency (TOF) and recyclability. The RGO/Fe25Co75 nanocomposites exhibit good catalytic activity toward 4-nitrophenol (4-NP) reduction and the graphene oxide (GO) supports also enhance the catalytic activity via a synergistic effect. The as-prepared RGO/FexCo100−x nanocomposite catalysts are very efficient, stable, easy to prepare, eco-friendly, cost-effective, and have potential industrial applications.

•New Ni-foam-supported and amine-functionalized TiO2 photocathodes were developed.•Energy band shifting is proved and attributed to organic ligand modification.•The light quantum efficiency reaches 1.2%, which is 2 times better than for plants.•Isotropic labeling and photoelectrochemical experiments prove the carbon source.We report new insights into the photoelectrochemical reduction of CO2 in a photoelectrochemical system, which is assembled from a nickel foam covered with TiO2 modified by covalent ligands as photocathode and BiVO4 as photoanode. These photoelectrocatalytic cells generate mainly methanol as a product in the liquid phase. Our results show that imine-functionalized TiO2/Ni has the highest activity. The formation rate of methanol in this excellent cell is up to 153 μM/h · cm2, which is about 15 times higher than that of the TiO2/Ni electrode. If the Faradaic efficiency is considered as 100%, the light quantum efficiency of this cell reaches 1.2%, that is two times better than that of plants. Isotopic labeling experiments with 13CO2 confirm that the detected products are produced exclusively by the reduction of CO2 and water splitting.Download high-res image (69KB)Download full-size image

A novel, “wet” and “clean” methodology was developed to prepare FexCo100−x nanoparticles on reduced graphene oxide (RGO) surfaces in an aqueous solution through a coreduction process. Without any surface treatment, FexCo100−x nanoparticles can in situ grow on the RGO sheets. It was found that RGO nanosheets can effectively prevent the aggregation of FexCo100−x nanoparticles. The results reveal that the RGO/FexCo100−x nanocomposites have ferromagnetic characteristics and show composition dependent magnetic properties. The effectiveness of the as-prepared RGO/FexCo100−x nanocomposites as solid phase heterogeneous catalysts have been evaluated, for the first time, on the well-known 4-nitrophenol (4-NP) reduction to 4-aminophenol (4-AP) in the presence of excess sodium borohydride. The effect of initial 4-NP concentration, and catalyst loading dose were evaluated. The catalyst efficiency was examined on the basis of turnover frequency (TOF) and recyclability. The RGO/Fe25Co75 nanocomposites exhibit good catalytic activity toward 4-nitrophenol (4-NP) reduction and the graphene oxide (GO) supports also enhance the catalytic activity via a synergistic effect. The as-prepared RGO/FexCo100−x nanocomposite catalysts are very efficient, stable, easy to prepare, eco-friendly, cost-effective, and have potential industrial applications.