Effect of Surfactant Stabilizers on the Distribution of Carbon Nanotubes in Aqueous Media

The results of a study on the homogeneity of suspensions are described considering the effect of different types of surfactant stabilizers and their concentrations on the uniform distribution of a carbon nanotubes（CNTs）-based modifying additive to construction materials in an aqueous medium. This problem was solved herein by using surfactants and ultrasound. The sonication treatment of CNTs particle agglomerates allowed for dispersing their globules and achieving a 15-20-fold decrease in their average size, for which it became possible to make better use of the CNTs as cement modifier. As a result of the experimental studies carried out, the effect of the surfactant type and concentration promoting uniform distribution of the CNTs in the bulk of the suspension and, correspondingly, in the structural composite matrix was revealed. The CNTs-based additive improved the physical-mechanical and operational characteristics of the material.

Heterojunction： important strategy for constructing composite photocatalysts

As an ideal solution to energy and environment issues,conversion of sunlight into solar fuels by photocatalytic water splitting and greenhouse gas(CO_2)reduction has attracted keen research interest of multi-field scientists.In the past four decades,a large number of semiconductor photocatalysts have been

Factors affecting photocatalytic performance through the evolution of the properties due to the phase transition from NaBiO_(3)·2H_(2)O to BiO_(2−x)

The phase transition process of a photocatalytic system from NaBiO_(3)·2H_(2)O to BiO_(2−x) has been investigated to understand the important factors that affect photocatalytic performance in a composite system. It is found that a proper amount of BiO2−x on the surface of NaBiO_(3)·2H_(2)O could effectively suppress the electron/hole recombination and increase the exposed reactive sites for photocatalytic reaction. A fully covered BiO2−x on NaBiO3·2H2O results in a dramatical decrease of photocatalytic degradation of dye. An over long hydrothermal process can result in BiO_(2−x) with reduced oxygen vacancies, which degrades the photocatalytic activity. Furthermore, the photocatalytic reduction ability of CO_(2) conversion has been investigated, indicating that the surface activity to different reactants also directly affects the catalytic performance. The investigation of the gradient phase transition process presents a clear guidance to construct a desired photocatalytic system, in addition to selecting gradient materials with suitable bandgap structure and a morphology with different fraction and distribution of each component. The defect evolution of each component during construction of a composite is also an important factor that should be optimized and considered in making a composite to achieve high photocatalytic efficiency.