A nitrogen-doped TiO2@SiO2 core/shell nano-photocatalyst (N-TiO2@SiO2) was used as an additive in photocatalytic paint and applied for the photocatalytic degradation of gaseous acetaldehyde under light-emitting diode (LED) visible light irradiation. N-TiO2 was synthesised via the solvothermal method and then encapsulated by SiO2 via the sol-gel method. The incorporation of the N atom into the TiO2 structure was observed by X-ray photoelectron spectroscopy. The N-TiO2@SiO2 core/shell structure was determined by TEM images. The photodegradation of gaseous acetaldehyde using the prepared N-TiO2@SiO2 photocatalytic paint was examined in a closed chamber under LED light irradiation. The photodegradation of acetaldehyde by N-TiO2@SiO2 photocatalytic paint (31%) was significantly higher than that of TiO2 paint (5%) and N-TiO2 paint (20%) within 16 h. The chemical resistance and adhesion ability of N-TiO2@SiO2 photocatalytic paint were investigated following Thai Industrial Standards (TIS) no. 2321 and standard test methods for rating adhesion by tape test (ASTM D 3359-22). The N-TiO2@SiO2 paint showed good acid and alkali resistance, as well as high adhesion ability comparable with commercial paint (without a photocatalyst).

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Nitrogen-doped titanium dioxide (NT) was synthesized by solvothermal method. Titanium (IV) butoxide (TBOT) was used as a titanium source and diethyleneamine (DEA) was used as a nitrogen source. The DEA concentration was fixed at 5% mol. The effect of the synthesized temperatures was studied (150 °C to 200 °C). The characterization results showed that the XRD patterns of NT synthesized by solvothermal method exhibited only anatase structure of TiO2 at 25.56° (101), 37.76° (004), 48.04° (200), 48.18° (105), 54.06° (211), 55.24° (204), 62.76° (116), 69.04° (220), 70.32° (215) and 75.30° (303). The crystallite sizes of NT (13-14 nm) were smaller than that of TiO2 (22.39 nm) while the surface area of NT (31-47 m2g−1) was larger than that of TiO2 (6.42 m2g−1). This indicated that doping N on TiO2 had a significant effect on crystallite size and surface area of TiO2. The photocatalytic activities of NT were evaluated by decolorization of 10−5 M methylene blue (MB) under LED visible light irradiation. The result showed that the photocatalytic performance of TiO2 was significantly improved by N dopant with the efficiency of 90%. However, the synthesized temperatures had no significant effect on the physical properties and the photocatalytic reactivity of NT.