Next-Generation Sustainable Adobe Materials: Multifunctional Coatings Based on LaFeO3 Nanoparticles and Hydro- and Oleo-Repellent Formulations

Adobe is a sustainable yet highly porous construction material, inherently vulnerable to moisture and environmental pollution, which poses challenges for both contemporary construction and heritage conservation. This study presents multifunctional coatings that combine hydrophobic/oleophobic and photocatalytic properties to enhance adobe durability. The coatings incorporate nano-heterostructured LaFeO3 photocatalysts into water-repellent and hydro-oleo-repellent formulations, selected to preserve the characteristic dark brown color of adobe. Microstructural analyses revealed the formation of non-uniform protective layers, particularly in hydro-oleo-repellent systems, which influenced performance. The treated surfaces exhibited significant water and oil repellency, while maintaining adequate vapor permeability. Durability tests confirmed improved resistance to water ingress, reduced capillary absorption, and enhanced erosion resistance compared to untreated adobe. Sustainability assessments highlighted the environmental and economic benefits of the proposed approach, especially when using locally sourced materials. Overall, this work proposes a scalable and multifunctional strategy that integrates protective and photocatalytic functionalities to extend the service life of both historical and modern adobe structures.