Flower-like ZnO microstructures were successfully produced using a hydrothermal method employing ZnSO4/(NH4)2SO4 as a raw material. The effect of the operating parameters of the hydrothermal temperature, OH?/Zn2+ molar ratio, time, and amount of dispersant on the phase structure and micromorphology of the ZnO particles were investigated. The synthesis conditions of the flower-like ZnO microstructures were: hydrothermal temperature of 160°C, OH?/Zn2+ molar ratio of 5:1, reaction time of 4 h, and 4 mL of dispersant. The flower-like ZnO microstructures were comprised of hexagon-shaped ZnO rods arranged in a radiatively. Degradation experiments of Rhodamine B with the flower-like ZnO microstructures demonstrated a degradation efficiency of 97.6% after 4 h of exposure to sunshine, indicating excellent photocatalytic capacity. The growth mechanism of the flower-like ZnO microstructures was presented. 相似文献
Monte Carlo simulations are employed in order to analyze the structure of polyelectrolyte complexes consisting of two identical but oppositely charged macroions with varying chain stiffness. It is shown that two complex structures can arise depending on the stiffness of the constituent chains. Stiff chains are organized into a “ladder” structure in which chains are located parallel to each other and monomeric units are arranged into ionic pairs according to their position in the chain. Flexible chains form a globular “scrambled‐egg” structure with a disordered position of monomer units. The conformational transition between the two structures proceeds as a phase transition.
Polymer semiconductors frequently form crystals or mesophases with lamellae, that comprise alternating layers of stacked backbones and side chains. Controlling lamellar orientation in films is essential for obtaining efficient charge carrier transport. Herein, lamellar orientation is investigated in an application-relevant setup: lamellae assembled on a substrate that strongly favors face-on orientation, but exposed to a film surface that promotes orientation along an “easy” direction, other than face on. It is assumed that the face-on order propagates from the substrate, but the lamellae bend to reduce their surface energy. A qualitative free-energy model is developed. The deformation is investigated as a function of film thickness, effective Young modulus, anchoring coefficient, and easy direction at the free surface. The calculations highlight the importance of elastic constants – lamellae can substantially deform already when Young moduli are only an order of magnitude smaller than the values that are reported for crystals. Softer Young moduli are expected when lamellar assembly occurs in a non-solidified mesophase that can be an equilibrium or (more speculatively) a transient state prior to crystallization. The alternative scenario of a two-layered film is also evaluated, where edge-on and face-on grains form, respectively, at the free surface and substrate. 相似文献
Bismuth oxychloride (BiOCl), although it has exhibited intensely potential used in photocatalyst for environmental remediation, owns wide bandgap and the fast photocharge recombination that limits its effective application. Doping BiOCl used in metal and non-metal elements simultaneously, as a feasible strategy in designing novel visible-light photocatalysts, was conductive to effectively overcome the as-above defects. The present work constructed S-Mo co-doped BiOCl-- with abundant reactive sites via one-pot hydrothermal method. The as-prepared S–Mo co-doped BiOCl sample presents the best-visible light-driven photodegradation performance, and its kinetic constant (k) is about 16.8 times (for rhodamine B) and 6.5 times (for tetracycline hydrochloride) higher than that of pure BiOCl, respectively. By contrast, S-Mo co-dopant induced the decrease of nanosheets size and endowed the large specific surface areas, which favors the increased reactive sites. Further analysis with the aid of experiments and density function theory calculations indicated that the intermediate level induced by S 2p orbitals could narrow the bandgap and promote the excitation of electron from conduction band to valance band via providing the middle springboard on the one hand, and the Mo energy states was conducive to promote the separation of charge carriers by acted as the acceptor for the photoinduced electrons on the other hand. Consequently, the potential origin of the improved visible-light-driven performance lies in the more superoxide radicals for oxidizing organic pollutants caused by the simultaneous enhancement of visible light absorption as well as charge separation resulted from the further optimization of energy band structure that associated with the doping energy level of S-Mo co-doping in BiOCl. This work demonstrated that S and Mo co-doping BiOCl is of highly promising candidate for the further progress of environmental remediation. 相似文献