Semiconductor photocatalyst films protecting stone cultural relics against microbial weathering
摘要
Microorganisms can colonize stone surfaces and metabolize them to produce pigments and corrosive products, thus causing the weathering of stone cultural relics. Herein, we show that weathering caused by a representative microorganism (Scenedesmus obliquus) can be prevented by coating stone surfaces with films comprising a semiconducting photocatalytic nanocomposite, BiVO4/Ti2NTx-TiO2. The compositing of BiVO4 (a narrow-bandgap semiconductor) with Ti2NTx-doped TiO2 (a two-dimensional layered semiconductor) results in an extended visible light absorption range and reduced bandgap. The incorporation of Ti2NTx increases the efficiency of light energy utilization and reactive oxygen species (•OH, •O2−) yield by enhancing electron conductivity and enabling the rapid transfer of photogenerated electrons (Ti2NTx to BiVO4 and TiO2). The reactive oxygen species produced upon the irradiation of BiVO4/Ti2NTx-TiO2 films with visible light selectively attack and kill harmful Cyanobacteria species, which feature a cyst-like structure composed of phospholipids and proteins, and the resulting release of intracellular nutrients promotes the growth of beneficial species (Proteobacteria, Actinobacteria, Bacteroidota, and Patescibacteria). Thus, this work paves the way for the protection of stone objects, including those classified as cultural heritage, and inspires the further development of semiconductor photocatalysts and their engineering applications.