Efficient removal of automobile exhaust by microporous humidity-regulated photocatalytic cement-based materials

The increasing NO pollution caused by the aggregation of urban automobile exhaust emissions has created an urgent need to develop a sustainable cement-based material that can remove NO. This study developed a Fe-TiO 2 /g-C 3 N 4 photocatalyst with high NO removal rate by using Fe-TiO 2 to enhance the ability of photogenerated electrons captured by the conduction band, and the heterojunction formed by the composite with g-C 3 N 4 to promote the charge separation and transport. Excellent sustainability was achieved with a NO removal rate of 52.3 % in a single test and a decay of only 5 percentage points in a 5-cycle test. Combination of the prepared photocatalyst and diatomite in the design of the photocatalytic cement-based material showed excellent NO removal performance and mechanical properties. The incorporation of diatomite increased the proportion of harmless pores, improved the microporous structure without degrading the mechanical properties, and enhanced the hygroscopicity of the photocatalytic cement-based materials (up to 21.76 %), which ensured the high efficiency of the photocatalytic NO removal process. Removal of NO from the cement blended with photocatalyst and diatomite was as high as 56.74 %, which was more than 20 % higher than that of the cement group blended with catalyst alone. The microporous humidity-regulated photocatalytic cement-based materials developed in this study provide a novel NO removal method for cities and can help realize the green development of sustainable cement-based materials.