An innovative g-C3N4/SiO2/PDMS composite coating with photocatalytic NO purification and self-cleaning functions

Abstract

As a traditional photocatalyst, UV-responsive TiO₂ has been widely favored, but its light energy utilization is lower than that of g-C₃N₄ with a visible light response. However, the photogenerated carriers of g-C₃N₄ have a low separation efficiency. In this study, SiO₂ was utilized as a carrier to compound with TiO₂ and g-C₃N₄ to ameliorate these flaws and advance their photocatalytic function. FT-IR, SEM, AFM, UV–Vis DRS, and PL were used to examine the optical performance, surface structure, and appearance of the composites. Taking the compounding ratio of SiO₂ and photocatalysts as a variable, NO purification rate as the evaluation index of photocatalyst pollution purification effect, and water and oil contact angle as the evaluation index of hydrophobicity and oleophobicity of photocatalytic coatings, the photocatalysts of SiO₂:TiO₂ = 3:1 and SiO₂:g-C₃N₄ = 5:1 were discovered to have the best photocatalytic effect among the same series of materials, with the latter having the greatest impact. The coatings of SiO₂:TiO₂ = 5:1 and SiO₂:g-C₃N₄ = 5:1 combined with PDMS exhibited the best hydrophobicity and oleophobicity of the same series of coatings, with the latter having the greatest effect. By varying the PDMS percentage in the SiO₂:g-C₃N₄ = 5:1/PDMS coatings, the optimal SCN5-1/P coating with 75% PDMS content was finally obtained, which had NO purification rate of 38.43%, and water and oil contact angles of 131.86° and 135.16°. This work provides a preparation method for producing high-efficiency photocatalytic self-cleaning coatings, which will aid in the advancement of photocatalytic self-cleaning technology.