Reproducible Synthesis of 6-Inch Adlayer-Free Graphene Single Crystals via Interfacial Chemical Potential Engineering

Chemical vapor deposition (CVD) synthesis of monolayer graphene single crystals on Cu(111) substrates has been regarded as a promising route toward controlled batch production. However, the widespread use of CVD-derived graphene remains hindered by the unavoidable formation of adlayers, which compromises thickness uniformity and property homogeneity. Current adlayer elimination strategies still suffer from narrow process windows, limiting scalability and reproducibility. Here, we identify the carbon chemical potential as a key factor determining adlayer formation and develop an interfacial chemical potential engineering strategy for the reproducible growth of 6-inch adlayer-free graphene single crystals. By constructing a symmetric dual-catalytic confinement, the chemical potential of active carbon species is effectively regulated, enlarging the tolerance for adlayer-free growth. Using this approach, twenty 6-inch monolayer graphene wafers are produced in a single batch with an expanded reaction window and a 4-orders-of-magnitude reduction in adlayer density. Furthermore, the effective elimination of adlayers improves the transfer intactness and electrical uniformity of as-received graphene, demonstrating an average carrier mobility of ∼8461 cm2 V-1 s-1 at room temperature and a sheet resistance of 401 ± 12 Ω sq-1 across the entire wafer. This work provides an effective strategy for adlayer suppression and establishes a reliable and scalable pathway toward wafer-scale monolayer graphene single crystals.