Organic-inorganic hybrid ZnS(butylamine) nanosheets and their transformation to porous ZnS.

Two-dimensional (2D) nanosheets possess the very essential features of nanomaterials, including quantum-confinement effects and unconventional reactivity, and are of special interest for a variety of promising applications. Here we report a facile chemical transformation strategy to prepare porous ZnS nanosheets via the organic-inorganic hybrid ZnS(butylamine) nanosheet-like precursor prepared from zinc diethyldithiocarbamate. The hybrid ZnS(butylamine) precursor show unique nanosheet-like structure composed by ZnS nanocluster region and non-crystalline region. The ZnS nanoclusters with crystallized state show the same crystal orientation in the nanosheets. A simple calcination process in nitrogen can induce the transformation of ZnS(butylamine) hybrid precursor to porous ZnS nanosheets. Different calcination temperature will cause the formation of porous ZnS nanosheets with different microstructure. In addition, the photoelectrochemical properties of the ZnS-based products including ZnS(butylamine) and porous ZnS nanosheets were investigated. This organic-inorganic hybrid precursor strategy to porous sulfides would also be suitable for fabricating other metal chalcogenides.

Small molecular amine mediated synthesis of hydrophilic CdS nanorods and their photoelectrochemical water splitting performance.

Photoelectrochemical (PEC) water splitting is a promising route for solar energy harvesting and storage, but it has been highly limited by the performance of the semiconductor photoelectrodes. Herein, we report a small molecular amine-mediated solvothermal method for synthesizing CdS nanorods. The obtained CdS nanorods are hydrophilic and can be easily dispersed in water. Furthermore, the small molecular amine, activating elemental sulfur and mediating the growth of CdS, all play a role similar to that of long-chain surfactant molecules in "non-aqueous" systems. Thus, the obtained CdS nanorods show uniform shape with monodispersed size, the length of which can be tuned by the sulfur dosage. In addition, the CdS nanorods show a broader light absorption than CdS nanoparticles. Their photoelectrochemical water splitting performances were then tested. Under light irradiation of λ > 200 nm, the photocurrent density of CdS nanorods at -0.2 V bias potential (vs. Ag/AgCl) is found to be 25 times of that obtained with CdS nanoparticles. The present finding demonstrates that small amine molecules could be efficient mediators for the synthesis of hydrophilic sulfides with high quality. The simple synthesis method and the good photoelectrochemical properties illustrate the hydrophilic CdS nanorods are potential candidate for photoelectrochemical applications.

Nanosheet-based hierarchical Ni(2)(CO(3))(OH)(2) microspheres with weak crystallinity for high-performance supercapacitor.

Three-dimensionally hierarchical oxide/hydroxide materials have recently attracted increasing interest by virtue of their exciting potential in electrochemical energy conversion and storage. Herein, hierarchical Ni2(CO3)(OH)2 microspheres assembled from ultrathin nanosheets were successfully synthesized by a one-pot/one-step hydrothermal route. In this method, common nickel salts and urea were selected as raw materials. The influence of urea concentration on the final product was studied. The hierarchical Ni2(CO3)(OH)2 microspheres show weak crystallinity and contain crystalline water. It was found that they exhibit excellent rate capacity when used as supercapacitor electrode. Under current density of 0.5 and 10 A/g, the optimized Ni2(CO3)(OH)2 electrode with loading density of 5.3 mg/cm(2) exhibited specific capacitances of 1178 and 613 F/g with excellent cycling stability. The excellent electrochemical property is possibly attributed to the intrinsic nature of Ni2(CO3)(OH)2, the ultrathin thickness of nanosheet units, and the sufficient space available to interact with the electrolyte. This facile synthesis strategy and the good electrochemical properties indicate that hydroxycarbonates are promising materials for supercapacitor application. This study suggests a large library of materials for potential application in energy storage systems.

Self-regulated route to ternary hybrid nanocrystals of Ag-Ag2S-CdS with near-infrared photoluminescence and enhanced photothermal conversion.

Developing hybrid nanocrystals is a hot topic in materials science. Herein, a ternary hybrid nanocrystal, Ag-Ag2S-CdS, combining near infrared emission and photothermal conversion properties was demonstrated. The ternary Ag-Ag2S-CdS hybrid nanocrystals with cubic shape and uniform size were synthesized by a simple one-pot and one-step colloidal method. The growth process is self-regulated with the formation order of Ag2S, Ag, and CdS, sequentially. The formation of Ag originates from the partial reduction of Ag2S, while the formation of CdS is through an Ag2S catalytic mechanism based on its superionic feature. The obtained ternary hybrid nanocrystals show near infrared emission and photothermal conversion properties in a lab-on-a-particle system. Importantly, an enhanced effect is observed for the photothermal conversion, which is mainly due to the presence of heterointerfaces among the crystals. This work will not only advance the synthesis chemistry of multi-component hybrid nanocrystals but also provide a possible route for the design of advanced multi-model materials used in bio-related fields.

Carbon-coated Zinc Sulfide nano-clusters: synthesis, photothermal conversion and adsorption properties.

Carbon-coated cluster-like ZnS nanospheres were synthesized by a facile solvothermal route. ZnCl2, thiourea, and glucose were selected as the raw materials. The formed ZnS with hexagonal phase has spherical cluster-like structure, which shows good monodispersity in size. A thin layer carbon is coated on the surface of ZnS cluster-like spheres. The thickness of carbon shell is dependent on the dosage of glucose. The carbon-coated ZnS nano-clusters show the same emission as that of pristine ZnS nano-clusters. Exposure of the aqueous dispersion of carbon-coated ZnS products to 980 nm laser can elevate its temperature by 5.1°C in 8 min. It was found that the photothermal conversion effect mainly comes from the carbon component and at the same time, the heterointerface between ZnS and carbon also provides a positive role for it. In addition, the carbon-coated ZnS products can absorb dye molecular with highest adsorption capacity of 36.8 mg/g toward Rhodamine B. The present finding demonstrates their potential applications in photothermal agents, adsorbents, and related fields.

Assembly of Ag3PO4 nanocrystals on graphene-based nanosheets with enhanced photocatalytic performance.

A facile fabrication of graphene oxide (GO)-Ag3PO4 nanocomposites has been achieved through a two-phase self-assembly process. The well anchoring of Ag3PO4 nanocrystals (NCs) on the GO nanosheets was confirmed by transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transform infrared spectra (FTIR), and Raman spectra. The significantly enhanced photocatalytic activity of the composites in comparison with bare Ag3PO4 NCs was revealed by the degradation of methylene blue (MB) under visible light irradiation, which can be attributed to the improved separation of electron-hole pairs and the high adsorption performance due to the presence of GO. The GO-Ag3PO4 can also be further photo-reduced into reduced graphene oxide (RGO)-Ag3PO4 nanocomposite without the formation of metal Ag. The RGO-Ag3PO4 nanocomposite exhibited higher photocatalytic activity and stability than bare Ag3PO4 NCs with the reason that the RGO nanosheets with high conductivity can effectively decrease the Ag formation during the cycling processes. This method developed here could be extended to design other high-performance graphene-based photocatalysts for environment and energy applications.