Graphene‐Enhanced Nanomaterials for Wall Painting Protection

Abstract Wall paintings as the highly valuable treasure have been facing severe damaging problems over the years. Ca(OH) 2 as a promising material to protect them has been studied for more than a decade. However, the synthesis methods are still costly, complex, and usually, involve an organic solvent. In addition, problems such as large particle size (>150 nm), slow and weak carbonation, and low consolidation strength for wall paintings remain unsolved. This study demonstrates an unprecedented concept of wall painting protection enabled by graphene‐enhanced nanomaterials through strategically synthesizing Ca(OH) 2 /graphene quantum dot (GQD) nanohybrids using a facile and economic aqueous method. The nanohybrids are uniform and small (center distribution at about 80 nm) and show strong adhesivity to wall painting pigments. In addition, the anti‐UV absorption ability of the nanohybrids is also a significant advantage. More importantly, the Ca(OH) 2 is fully carbonated into a stable CaCO 3 crystal phase “calcite” because of the GQD, which is crucial in wall painting consolidation. As a result, the graphene‐enhanced nanohybrids show superior conservation efficiency compared to as‐synthesized Ca(OH) 2 and commercial Ca(OH) 2 materials. The result opens a new direction for protecting cultural heritage using the newly emerging 2D nanomaterials.