Why Graphene Oxide and Nano-SiO2 Continue to Face Challenges in Architectural Coatings: A Systematic Review and Meta-Analysis

Graphene derivatives and nano-silicon dioxide (nano-SiO2) have been widely studied as functional nanofillers for architectural coatings. They have the potential to improve mechanical performance, barrier properties, durability, and versatility. However, despite encouraging results in laboratory settings, their use in commercial coating formulations is still limited. This is mainly due to challenges with dispersing nanoparticles, ensuring compatibility with polymer binders, maintaining long-term durability, and achieving formulation stability. In this work, we conducted a thorough review and meta-analysis of 20 peer-reviewed studies to evaluate the performance and limitations of graphene-based materials and nano-SiO2 in architectural and protective coatings. Our literature search followed PRISMA guidelines and included studies that provided quantitative data on dispersion methods, surface functionalization strategies, nanofiller loading levels, and coating performance metrics. This review highlights key relationships between structure, properties, and processing. It points out ongoing challenges that prevent practical use and suggests future research directions to enhance formulation design, improve dispersion stability, and extend the long-term performance of graphene- and nano-SiO2-modified architectural and protective coatings.