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CoP@C/g-C3N4 photocatalysts with enhanced charge transfer for efficient photocatalytic H2 generation.

The metallosupramolecular Ti-based M4L4 cage of [Ti4O2L4Cl8] (L = 4-acetamidobenzoic acid) is synthesized via the one-pot solvothermal reaction of 4-aminobenzoic acid, acetic acid and TiCl4. The Ti(iv) ion functions as a Lewis acid catalyst for acylation condensation, and then coordinates with the resultant 4-acetamidobenzoic acid to afford Ti-based cage formation in a cascade fashion.

We present a novel strategy to improve the stability and optical absorption of polyoxotitanates (POTs) via concurrently fully carboxylate-coordinating and hetero-metal-doping, and illustrate the strategy by an indium doped hetero-polyoxotitanate (h-POT) of a [Ti12In6O18(OOCC6H5)30] (POTi12In6) nanocluster, which possesses ultrahigh stability in both acid and base aqueous solutions. The nanocluster structurally features a core–shell double wheel structure and a polar cavity. Both experiments and theoretical calculations confirm the semiconductive properties of the nanocluster. Under visible irradiation the POTi12In6 nanocluster can produce pronounced photocurrent, and reactive oxygen species for pollutant degradation. Without using any cocatalyst, POTi12In6 exhibits important visible-light-driven photocatalytic activity for H2 evolution in an aqueous system. This work could render a polyoxotitanate as a new type of visible-photoactive photocatalyst.

Surface-enhanced Raman scattering (SERS) has been proven to be a powerful analytical tool for the detection of trace molecules because of its integration of high sensitivity, unique spectroscopic fingerprint, and non-destructive data acquisition. However, the lack of reliable, stable, well-defined, and uniform SERS substrates impedes their further practical applications. Herein, we have developed a SERS-active substrate based on a flexible and stable polymer (PDMS) film loaded with nanoparticles for ultrasensitive Raman signal readout and trace detection of pesticide residues in agricultural products and environments. By controlling the deposition of Ag nanoparticles, tremendous Raman enhancement can be achieved due to numerous hot spots generated among the Ag nanoparticles on the PDMS composite film. The flexible SERS film can be employed to detect rhodamine 6G (R6G) with an enhancement factor (EF) of 3.37 × 1011 and the pesticide thiram in commercial grape juice with a detection limit of as low as 0.1 μm (0.03 ppm), which is considerably lower than the maximum residue limit (MRL) of 7 ppm in fruit prescribed by the U.S. Environmental Protection Agency (EPA). Furthermore, spiked detection indicated that the AgNP–PDMS flexible film can be used to monitor thiram in commercial grape juice and natural lake water without further treatment. Therefore, the AgNP–PDMS flexible film enhanced Raman spectroscopic technique offers great potential for practical applications in the on-site monitoring and assessment of pesticide residues in agricultural products and environments.

Analytical techniques based on surface-enhanced Raman scattering (SERS) suffer from a lack of reproducibility and reliability, thus hampering their practical applications. Herein, we have developed SiO2@Ag nanospheres as an effective SERS detection platform through in situ loading Ag nanocontacts onto the SiO2 nanospheres, the well-designed and uniform nanocomposites provide highly enhanced effects for the tremendous SERS signal amplification. The huge enhanced effect might originate from the hot spots generated from the nanocontacts among the silver nanoparticles loaded onto the silica nanosphere, and also possibly from the nanogaps among the neighboring silver nanoparticles between the two silica nanospheres. The SERS enhancement factor of the SiO2@Ag nanospheres substrate is as high as 1016. Moreover, the as-fabricated SERS substrate can be employed to enhance the Raman signals of some chemicals that are harmful to environment including thiram, melamine and ethyl-parathion. The detection limits with the SERS platform are several orders of magnitude lower than the maximal residue limit (MRL) in fruit prescribed by U.S. Environmental Protection Agency (EPA). Therefore the surface lifting spectroscopic technique based on the SiO2@Ag nanosphere SERS platform offers great practical potential for the on-site assessment and identification of harmful chemicals with ultralow concentrations in agricultural products and environments.

We have developed a direct and scalable approach, based upon a thermal decomposition method under normal atmospheric pressure via an interface diffusion mechanism, for growing well-defined single-crystalline functional metal oxide nanobelts. Several metal oxide nanobelts including magnetic oxides, transparent conducting oxides, and other functional oxides can be synthesized on a large scale. The typical synthesis strategy involves the synthesis of the precursors via a solvothermal process and subsequently the fabrication of the nanobelts through thermal decomposition of the precursors at atmospheric pressure, and the sizes (the length and the width) of nanobelts can be easily tuned by modifying the heating temperature and the heating rate. This synthetic strategy might not only shed a new light on the facile, general synthesis and functional mechanisms of the functional metal oxide nanobelts, but also extend the practical applications of the nanobelts in a variety of fields.

The development and innovation of strategies for the fabrication of oriented nanostructures has been among the hot research topics in the field of nanoscience because of the novel properties of these nano-arrays, that differ drastically from their bulk counterparts, and their potential applications in many areas including the chemical, physical, biological and engineering fields. Herein, we have demonstrated an extremely simple procedure for the fabrication of a forest of oriented silver nanowires at ambient temperature in aqueous solution without a hard template. The oriented silver nanowire arrays exhibit better field emission performance than that of a single nanowire or non-oriented nanowires. By variation of the experimental parameters, the diameter and length of the oriented Ag nanowires can be tuned accordingly. The successful fabrication of a forest of the oriented nanowires under mild conditions without a template not only provides an efficient route to selectively control the preparation of oriented nano-arrays, but also provides new insights into the underlying surfactant-mediated mechanism of nano- and micro-architectures. This strategy might be extended to fabricate other metal and semiconductor nanocrystal arrays and widen their potential applications in many fields.

Molecular recognition events that occur at the interface between inorganic surfaces and organic molecules play a critical role in a wide field of technologically and scientifically relevant processes including heterogeneous catalysis, crystal growth, and the development of sensor systems based on functional materials. Herein, we have developed a general and versatile method for the controlled synthesis of nanosized silver crystals with different shapes ranging from microspheres assembled with nanoparticles, nanocubes, nanocones to one-dimensional (1D) nanostructures including nanobelts and nanohelixes. These well-defined morphologies were obtained by controlling the relative growth rate of the crystal plates by selective use of capping ligand mixtures. The method involves the slow chemical reduction of the silver precursor by amine molecules. It is known that certain amines function as weak (and thus slow) reductants and as metal coordination ligands for metal complexes in solution. Both these properties should contribute to a slow rate of crystal growth and hence to the formation of special shapes under different solutions. We have used dodecylamine (DA) in combination with other amine ligands under selected solvents for the synthesis of the silver nanocrystals with different shapes. By changing the composition of the amine ligand mixture, nanosized crystals with different feature shapes and sizes can be obtained. Our results suggest a general strategy for the morphology controlled synthesis of metallic nanocrystals with different feather shapes: utilization of molecular recognition at the crystallographic planes under slow-growth conditions.