Mesoporous nanosheets-assembled flower-like SrTiO3/Ag nanoparticle composites with tunable Ag content were constructed via room-temperature liquid-phase deposition of Ag nanoparticles on mesoporous nanosheets-assembled flower-like SrTiO3, which was pre-synthesized by a facile solvothermal approach and subsequently annealed in air. The as-fabricated nanocomposites were Ag nanoparticles with a size of ca. 2 nm uniformly distributed on the surface of the mesoporous nanosheets-assembled flower-like SrTiO3 of about 600 nm in diameter. The Ag content on the flower-like SrTiO3 greatly affected the catalytic performance for the photodegradation of methyl orange and the catalytic reduction of 4-nitrophenol, and there was a different optimum amount of Ag nanoparticles for the two kinds of catalytic reactions. The optimum Ag@SrTiO3 nanocomposite exhibited a much-enhanced full-arc light photocatalytic activity for the degradation of methyl orange and excellent activity and stability for the catalytic reduction of 4-nitrophenol. This work provides a simple method to synthesize an Ag@SrTiO3 nanocomposite, developing a new catalyst for the photocatalytic degradation and catalytic reduction of organic pollutants.

Crystal facet engineering and surface modification of semiconductor have become important strategies to improve photocatalytic activity by optimizing surface charge carrier separation/transfer and extending solar spectrum utilization. In this work, we report anatase single-crystalline TiO2 hollow tetragonal nanocones with large exposed (1 0 1) facets by a facile liquid-phase interfacial synthetic strategy, using the hydrolysis of tetrabutyltitanate with adscititious water in the organic solvent of cyclohexane and a capping agent of 1, 6-hexanediamine. The specific surface area of these TiO2 hollow tetragonal nanocones is as high as 331.3 m2/g. Thanks to large exposed (1 0 1) facets and high surface area, these TiO2 hollow tetragonal nanocones exhibited excellent full-arc photocatalytic activities for the degradation of organic pollutants. Remarkably, the butoxy group could be modified onto TiO2 hollow tetragonal nanocones through post-synthesis treatment in tetrabutyltitanate glycol solution, which brought about eximious visible light photocatalytic activities for the degradation of colored dyes of RhB and MO, especially for RhB, by virtue of much improved electron trapping ability of the Ti-O group from the excited dye due to the strong electronegativity of the oxygen atom in the butoxy group. This work advances us to rationally tailor the atomic and electronic structure of the photocatalyst for outstanding photocatalytic properties in various environmental and energy-related applications.Download high-res image (266KB)Download full-size image

Defect-rich MoS2 ultrathin nanosheets with abundant unsaturated sulfur atoms are constructed using a stoichiometric ratio of Mo(VI) and L-cysteine in the presence of 1,6-hexanediamine. The as-prepared MoS2 ultrathin nanosheets exhibit excellent electrochemical activities in lithium-ion batteries and supercapacitors with a high reversible capacity and good cycling stability. The construction of defects with abundant unsaturated sulfur atoms in the MoS2 ultrathin nanosheets provided active sites for improving the electrochemical performance in lithium-ion batteries and supercapacitors. This work provides an accessible foundation for engineering more sophisticated defect-rich MoS2 ultrathin nanosheet-based composites for further optimization across a range of possible domains of application.

The surface modification of semiconductors is an important strategy for tuning solar-driven photocatalytic activity. Herein, ZnO nanorods/ZnSe heteronanostructure arrays with a tunable microstructure of the ZnSe shell, with a high visible light photocatalytic activity, are produced by liquid chemical conversion using ZnO nanorods arrays on a zinc foil. By varying the ammonia concentration, the secondary ZnSe shell can be formed of nanoparticles, nanorods and nanosheets, engineered by the oriented attachment of small ZnSe nanoparticles. By virtue of the synergistic advantages of the enhanced visible light adsorption capability and the effective separation of electron–hole pairs obtained by coupling ZnO nanorods with ZnSe nanostructures, the ZnO nanorods/ZnSe heteronanostructure arrays exhibit high visible light driven photocatalytic activities as well as shell microstructure dependent photocatalytic performances.

Novel hierarchical heteronanostructures of ZnO nanorods/ZnS·(HDA)0.5 (HDA = 1,6-hexanediamine) hybrid nanoplates on a zinc substrate are successfully synthesized on a large scale by combining hydrothermal growth (for ZnO nanorods) and liquid chemical conversion (for ZnS·(HDA)0.5 nanoplates) techniques. The formation of ZnS·(HDA)0.5 hybrid nanoplates branches takes advantage of the preferential binding of 1,6-hexanediamine on specific facets of ZnS, which makes the thickening rate much lower than the lateral growth rate. The ZnS·(HDA)0.5 hybrid nanoplates have a layered structure with 1,6-hexanediamine inserted into interlayers of wurtzite ZnS through the bonding of nitrogen. The number density and thickness of the secondary ZnS·(HDA)0.5 nanoplates can be conveniently engineered by variation of the sulfur source and straightforward adjustment of reactant concentrations such as 1,6-hexanediamine and the sulfur source. The fabricated ZnO/ZnS·(HDA)0.5 heteronanostructures show improved electrochemical catalytic properties for hydrazine compared with the primary ZnO nanorods. Due to its simplicity and efficiency, this approach could be similarly used to fabricate varieties of hybrid heterostructures made of materials with an intrinsic large lattice mismatch.

Semiconductor–metal heteronanostructures provide an effective way to tailor the properties of semiconductor photocatalysts through promoting interfacial charge-transfer processes and enhancing charge separation. Here, a zinc substrate strategy has been developed for the solution-phase synthesis of well-defined ZnO nanorods/Pt and ZnO nanorods/Ag heteronanostructure arrays in high yields. The fabricated heteronanostructure arrays show significant structure-induced enhancements of photodegradation for rhodamine B and high photocatalytic stabilities, which are very attractive for real photocatalytic applications.

Needle-like ZnO nanorods (ZnO–NRs)/Ag nanoparticles (Ag–NPs) heterostructures with tunable silver contents have been successfully designed and constructed via a two-step hydrothermal approach on zinc foil. The as-fabricated heteroarchitectured composite was Ag–NPs with a size range about 30 to 50 nm in diameter assembled uniformly on the surface of needle-like ZnO–NRs, several micrometers long and about 480 nm wide near the half height of the nanorods. Through the variation of the reactant concentration such as silver nitrate, the silver content on the ZnO–NRs can be controllably tuned, which further greatly affected the photocatalytic performance of the decomposition of a representative dye pollutant of rhodamine B, and there is an optimum amount of secondary Ag–NPs. This facile method developed here also can be extended to construct other ZnO-based noble metal or semiconductor heterostructures on zinc substrates.

•The mesoporous MgO nanosheets were successfully synthesized.•The product was used to construct an electrochemical sensor on GCE.•The electrode was applied to determine Hg(II), Cu(II), Pb(II) and Cd(II).•The sensor exhibits high sensitivity and selectivity.The mesoporous MgO nanosheets with uniformly distributed mesoporosity and high specific surface area of 102.8 m2/g were simply synthesized on a large scale by calcination of hexagonal Mg(OH)2 nanosheet precursor, which was prepared using 1,6-hexanediamin-assisted solution approach. The as-prepared mesoporous MgO nanosheets were used to construct a cheap, easy and environmentally-friendly electrochemical sensor on glassy carbon electrode for the simultaneous and selective electrochemical determination of four toxic metal ions of Hg(II), Cu(II), Pb(II) and Cd(II) in an aqueous solution, which exhibits high sensitivity and selectivity. The DPV responses of the sensor toward separate measurements of Hg(II), Cu(II), Pb(II) and Cd(II) at different concentrations show the linear detection range was 0.005–1.71, 0.01–2.13, 0.01–2 and 0.01–0.21 μM. The simultaneous and selective determination of these species in the quaternary mixtures presents the linear responses in the range of 0.005–1.71, 0.01–1.92, 0.01–1.76 and 0.01–0.2 μM. The favorable performance makes this sensor extremely attractive for onsite environmental monitoring of heavy metal ions.

Folding flake-like CuO sub-microstructure was successfully prepared on a large scale using a facile 1, 6-hexanediamin assisted low-temperature solution approach. The growth mechanism of the sample was discussed based on the time-resolved experiments. The experimental results demonstrated that the microstructures of CuO strongly depended on the concentration of the 1, 6-hexanediamin. The as-prepared CuO sub-microstructures were dispersed in Chitosan solution to fabricate composite film on glass carbon electrode. The electrochemical study has shown that the folding flake-like CuO sub-microstructure exhibits highest catalytic effect on Hg2+ than other CuO sub-microstructures. The amperometric response exhibited that the folding flake-like CuO sub-microstructure modified glassy carbon electrode has a good response for Hg2+ with a linear range of 1–200 μM in pH 6.0 phosphate buffered solutions.

NiO nanosheets with uniformly distributed mesoporosity were successfully synthesized on a large scale by calcination of β-Ni(OH)2 nanosheet precursor, which was simply prepared using 1,6-hexanediamine-assisted solution approach. The as-prepared mesoporous NiO nanosheets have been introduced for the first time for the sensing of mercury ions, which were found to be useful for selective electrochemical detection of Hg2+ with a linear range of 0.8 to 500 μM in pH 6.0 phosphate-buffered solutions, providing us another opportunity for exploring new electrochemical application of NiO nanomaterials.

Defect-rich MoS2 ultrathin nanosheets with abundant unsaturated sulfur atoms are constructed using a stoichiometric ratio of Mo(VI) and L-cysteine in the presence of 1,6-hexanediamine. The as-prepared MoS2 ultrathin nanosheets exhibit excellent electrochemical activities in lithium-ion batteries and supercapacitors with a high reversible capacity and good cycling stability. The construction of defects with abundant unsaturated sulfur atoms in the MoS2 ultrathin nanosheets provided active sites for improving the electrochemical performance in lithium-ion batteries and supercapacitors. This work provides an accessible foundation for engineering more sophisticated defect-rich MoS2 ultrathin nanosheet-based composites for further optimization across a range of possible domains of application.

The surface modification of semiconductors is an important strategy for tuning solar-driven photocatalytic activity. Herein, ZnO nanorods/ZnSe heteronanostructure arrays with a tunable microstructure of the ZnSe shell, with a high visible light photocatalytic activity, are produced by liquid chemical conversion using ZnO nanorods arrays on a zinc foil. By varying the ammonia concentration, the secondary ZnSe shell can be formed of nanoparticles, nanorods and nanosheets, engineered by the oriented attachment of small ZnSe nanoparticles. By virtue of the synergistic advantages of the enhanced visible light adsorption capability and the effective separation of electron–hole pairs obtained by coupling ZnO nanorods with ZnSe nanostructures, the ZnO nanorods/ZnSe heteronanostructure arrays exhibit high visible light driven photocatalytic activities as well as shell microstructure dependent photocatalytic performances.