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Litharge, in two dimensional (2D) nanostructure form, has recently ignited considerable theoretical interest due to its excellent photoelectric and magnetic properties. However, the lack of an efficient synthesis method hinders its development. Here, we provide an interfacial solvothermal strategy for controllably synthesizing ultrathin hexagonal polycrystalline α-PbO nanosheets in micrometer scale. This strategy can also be utilized for the synthesis of other 2D materials. Experimental atomic force microscope nanoindentation measurements reveal the relationship between the thickness of polycrystalline α-PbO nanosheets and the corresponding Young's modulus, expressed as E = E0 + Kt -1. First-principles calculation supports the result and ascribes the cause to interlayer sliding from particular weak interlayer interactions. Additionally, the enhanced mechanical strength of the polycrystalline structure compared to its single-crystal counterpart is attributed to the alternate arrangement of grain-boundaries effects. The summative formula may be extended to other 2D materials with weak interlayer interactions, which has the potential to provide guidance for constructing flexible devices.

This paper reports the synthesis of semiconductor nanocrystals of PbS through a facile and inexpensive synthetic route between lead acetate [Pb(Ac)2·3H2O] and dithioglycol (HSCH2CH2SH) without any surfactant. The products were characterized by x-ray diffraction (XRD), transmission electron microscopy (TEM), high-resolution TEM (HRTEM), Raman spectroscopy, x-ray photelectron spectroscopy (XPS) and infrared (IR) spectroscopy. The size of cube-shaped PbS nanocrystals can be controlled by changing the relative amount of Pb(Ac)2·3H2O and dithioglycol. Smaller cube-shaped PbS nanocrystals were obtained at higher sulfur content in the reaction system. The nanometre-sized single crystals of PbS measure ~83 nm × 59 nm × 22 nm and 39 nm × 10 nm × 7 nm, for lead acetate:dithioglycol ratios of 1:0.375 (denoted as PbS-1) and 1:1.5 (denoted as PbS-2), respectively, when a mixture of NaOH solution of lead acetate and ethyl alcohol solution of dithioglycol is maintained at 220 °C for 4 h in a Teflon-lined autoclave. XRD patterns and HRTEM images confirm the crystalline structure of the PbS crystals. TEM helped to determine the dimension of the single crystals. Raman, XPS and IR helped to further demonstrate the purity of the as-synthesized samples. The optical absorption spectra of suspensions of the these crystals in glycol show shifts in absorption band edge for as-prepared sample PbS-1 from 246 to 271 nm and for PbS-2 from 246 to 275 nm, after four days of storage, respectively. The photoluminescence peaks from the two samples are located at 434 and 433 nm for photoexcitation radiation of 315–355 nm, thus exhibiting a Stokes shift compared with band edge energy. The principal contribution of this work is that the nanometre-size PbS single crystals are prepared without using a surfactant or templating agent. The formation of a five-membered ring via the chelation between the Pb2+ ion and dithioglycol is considered to be crucial in this mechanism.

This paper reports the synthesis of semiconductor ZnSe microspheres composed of nanoparticles via a solvothermal route between the organic molecule selenophene (C(4)H(4) Se) and ZnCl(2) without adding any surfactant. The ZnSe microspheres were characterized by x-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM), specific surface area measurement, and photoluminescence (PL) spectra. A strong and broad blue PL emission at 443 nm in wavelength (∼2.79 eV in photon energy) is attributed to the near-band-edge (NBE) emission of ZnSe, while the 530 nm peak is a defect-related (DL) emission. The photocatalytic activity of the as-prepared ZnSe microspheres was evaluated by photodegradation of methyl orange (MO) dye under ultraviolet (UV) light and visible light irradiation. The degradations of MO reach 94% or 95.1%, close to 100%, in the presence of the as-synthesized ZnSe microspheres or commercial ZnSe powder after 7 or 10 h under UV irradiation, respectively. Meanwhile the degradations of MO reach 94.3% or 60.6% in the presence of the as-synthesized ZnSe microspheres or commercial ZnSe powder after 12 h, respectively. The degradation rate of ZnSe microspheres is twice that of ZnSe commercial powder under UV light irradiation, and three times under visible light irradiation. The degradation process of MO dye on ZnSe microspheres under UV or visible light is also discussed.

In this paper, we report a biomolecule-assisted soft chemistry route for constructing complex Bi2S3nanostructures that exhibit controlled wetting behavior. The as-synthesized sample was characterized by x-ray diffraction (XRD), scanning electron microscopy (SEM), field emission SEM (FE-SEM), transmission electron microscopy (TEM), high-resolution TEM (HRTEM), Fourier transform infrared (FT-IR), Raman, x-ray photoelectron (XPS) and photoluminescence (PL). The Raman spectra indicate that the surface optical (SO) phonon mode occurs in Bi2S3nanoparticles. The SO phonon mode is attributed to the defects on the surface of Bi2S3nanoparticles. In addition, the possible formation mechanism of the self-assembled urchin-like Bi2S3complex nanostructures is discussed. The established complex nanostructure can control the surface topology of a membrane to create a superhydrophobic surface. A water contact angle (CA) of > 150° of the as-synthesized Bi2S3complex nanostructures can be obtained, which may find potential application in environmental chemistry.