The Preparation of g-C3N4/CoAl-LDH Nanocomposites and Their Depollution Performances in Cement Mortars under UV-Visible Light

NOx degradation ability of S-g-C3N4/MgAl-CLDH nanocomposite and its potential application in cement-based materials

In this study a new photocatalytic nanocomposite, S-g-C₃N₄/MgAl-CLDH, was synthesized and implemented into cement mortar by internal mixing or coating. The photocatalytic NO_x degradation efficiency of the S-g-C₃N₄/MgAl-CLDH and photocatalytic mortar was investigated. The NO_x degradation efficiency and photoluminescence spectra of S-g-C₃N₄/MgAl-CLDH after being immersed in the simulated concrete pore solution were evaluated to assess its chemical stability. The results show that compared with S-g-C₃N₄, the S-g-C₃N₄/MgAl-CLDH exhibits a narrower bandgap (2.45 eV), a lower photogenerated electron-hole pair recombination rate and a higher specific surface area (36.86 m² g^-1). After 21 min of visible light irradiation, the NO_x degradation rate of S-g-C₃N₄/MgAl-CLDH achieves 100% as compared to merely 81.5% of S-g-C₃N₄. After being submerged in simulated concrete pore solution, the S-g-C₃N₄/MgAl-CLDH exhibits only a slight decrease of 5% in degradation rate after 12 min of irradiation, confirming a good compatibility and stability in cement-based materials. The NO_x degradation ability of the internally mixed mortar is enhanced with an increase in the dosage of S-g-C₃N₄/MgAl-CLDH. For coated mortar, in contrast, a decline in NO_x degradation rate is observed after 5 layers of coating owing to the lower porosity of mortar after excessive coating.

Visible light antibacterial potential of cement mortar incorporating Cu-ZnO/g-C3N4 nanocomposites

In this work, a hybrid Cu-ZnO/g-C₃N₄ nanocomposite was synthesized and introduced to fabricate photocatalytic cement mortars by internal mixing. The bactericidal properties of the photocatalytic mortars were explored by using E. coli, S. aureus and P. aeruginosa as a bacteria test strain. The results showed that the Cu-ZnO/g-C₃N₄ nanocomposite had an enhanced harvesting of visible light energy and exhibited excellent stability during the photocatalytic process, which favored a long-term usage performance. The sterilizing efficiency of the photocatalytic cement mortars improved with an increasing content of Cu-ZnO/g-C₃N₄ nanocomposites. A possible bactericidal mechanism was proposed based on the active species trapping experiments, verifying that the photogenerated holes (h⁺) and ˙O₂⁻ radicals were the main active species.

A hybrid Cu-ZnO/g-C₃N₄ nanocomposite was synthesized and introduced to fabricate photocatalytic cement mortar whose bactericidal activity was investigated under visible light.

Photoactive Cements: A Review

This article presents a short overview of modified cements with photocatalytic activity. First, the types and three main methods of obtaining photoactive cements are presented. The most frequently used modification method is the incorporation of a photocatalyst into the total mass of the cement. The second group analyzed is cements obtained by applying a thin layer of photoactive materials, e.g., paints, enamels, or TiO₂ suspensions, using various techniques. The third group is cement mortars with a thick layer of photoactive concrete on the top. In addition, methods for determining the photoactivity of cement composites, mechanical properties, and physicochemical parameters of such materials are briefly presented. Finally, examples of investments with the use of photoactive cements and development prospects are shown.