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In this study a new photocatalytic nanocomposite, S-g-C 3 N 4 /MgAl-CLDH, was synthesized and implemented into cement mortar by internal mixing or coating. The photocatalytic NO x degradation efficiency of the S-g-C 3 N 4 /MgAl-CLDH and photocatalytic mortar was investigated. The NO x degradation efficiency and photoluminescence spectra of S-g-C 3 N 4 /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-C 3 N 4 , the S-g-C 3 N 4 /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 m 2 g -1 ). After 21 min of visible light irradiation, the NO x degradation rate of S-g-C 3 N 4 /MgAl-CLDH achieves 100% as compared to merely 81.5% of S-g-C 3 N 4 . After being submerged in simulated concrete pore solution, the S-g-C 3 N 4 /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-C 3 N 4 /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., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (This journal is © The Royal Society of Chemistry.)

In this work, a hybrid Cu-ZnO/g-C 3 N 4 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-C 3 N 4 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-C 3 N 4 nanocomposites. A possible bactericidal mechanism was proposed based on the active species trapping experiments, verifying that the photogenerated holes (h + ) and ˙O 2 - radicals were the main active species., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)