Chunlin Bao

Nanosheet-Based Hierarchical Ni2(CO3)(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.

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.

Polymer guided synthesis of Ni(OH)2 with hierarchical structure and their application as the precursor for sensing materials

Hierarchical Ni(OH)2 microstructures with sizes of several micrometers have been synthesized through a polymer mediated self-assembly route. The hierarchical Ni(OH)2 microstructures are built of sheet-like building blocks, which are further composed of “side to side” stacking of tiny sheet-like units. The influence of various experimental parameters on the microstructure was investigated. It is believed that the polymer, poly(sodium-4-styrene sulfonate), selectively bonded on the surface of Ni(OH)2 clusters mediates the formation of hierarchical Ni(OH)2 microstructures. In addition, through the chemical conversion of Ni(OH)2 to NiO, an oxide sensor was fabricated, which exhibits excellent gas sensing performances to ethanol and propanol, suggesting the potential applications. It is also anticipated that these Ni(OH)2 microstructures will have successful applications in Ni-based batteries, electrodes, and so on.

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.

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.

Phase purification of Cu–S system towards Cu1.8S and its catalytic properties for a clock reaction

Controlling the composition and crystal phase is an important issue to tune material physical/chemical properties. Herein, it was found that triphenyl phosphine (TPP) can be used as a phase transfer agent to transform CuS, Cu39S28 phases into pure low-sulfur Cu1.8S phase. When mixed phase copper sulfides were reacted with triphenyl phosphine under suitable temperature, sulfur was extracted to produce the low-sulfur Cu1.8S phase. It was also demonstrated that the Cu–S product can effectively catalyze a clock reaction between methylene blue and hydrazine in aqueous medium. In addition, the photothermal conversion properties of the Cu–S based products were studied. The results show that the purified Cu1.8S materials show enhanced or similar properties than the original mixed-phase Cu–S products.

Ag2S–CoS2 hetero-nanostructures: One-pot colloidal synthesis and improved magnetic properties

Ag2S–CoS2 hetero-nanostructures with well defined and sharp hetero-interface were synthesized with a simple one-pot colloidal chemical route. It is proposed that the Ag2S nanoparticles with superionic conductor properties play a catalyst role inducing the growth of CoS2. The magnetic properties of the Ag2S–CoS2 hetero-nanostructures were investigated, which gives a saturation magnetization of 8.3 emu/g at 1.8 K and transition temperature of 120 K. It is believed that the reported results would give some hints to the development of multifunction magnetic materials.