Lai Cheuk Yui, Lin Yu-Xuan, Lin En-Jing, Lin Ching-Chih, Chen Chiao-Chen
Department of Chemistry, National Cheng Kung University, No.1, University Road, Tainan City 701, Taiwan.
ACS Appl Mater Interfaces. 2025 Sep 24;17(38):54214-54229. doi: 10.1021/acsami.5c11957. Epub 2025 Sep 12.
Graphene, a two-dimensional nanomaterial with excellent physicochemical properties, has considerable potential to functionalize surfaces for diverse applications. However, reliable methods for preparing uniform conformal graphene on complex surfaces are still limited. In this study, we develop a practical strategy for the direct growth of conformal graphene coatings on silicon substrates textured with randomly distributed micropyramidal structures. The produced transfer-free graphene exhibits high uniformity (monolayer content ∼95%), low defect density, and excellent conformality, even across high-curvature features, such as micropyramid apexes. The graphene films not only faithfully replicate the underlying microstructures but also contribute to advantageous surface properties, including strong fluorescence quenching, excellent chemical stability, enhanced molecular adsorption, and improved charge-transfer interactions. All these properties are crucial for effective surface-enhanced Raman scattering (SERS). This graphene-coated pyramidal substrate enabled reproducible and stable SERS detection of rhodamine 6G (R6G), exhibiting high sensitivity with a detection limit of ∼10 M, excellent long-term stability over 30 days, and low spatial signal variation of ∼10% at the millimeter scale. By further decorating the graphene-coated pyramidal substrate with silver nanoparticles, the detection limit was improved to 5.5 × 10 M for R6G with a high analytical enhancement factor of 1.08 × 10. This enhanced performance arose from the synergistic interplay between the light-trapping capability of the microstructured surface, the chemical enhancement caused by the graphene interface, and the electromagnetic amplification provided by the plasmonic nanoparticles. These findings offer valuable insights into the design of high-performance SERS platforms. This study also presents a practical method for the direct synthesis of conformal graphene for surface functionalization that is promising for a wide range of applications in sensing, optoelectronics, and catalysis.
石墨烯是一种具有优异物理化学性质的二维纳米材料，在使表面功能化以实现各种应用方面具有巨大潜力。然而，在复杂表面上制备均匀保形石墨烯的可靠方法仍然有限。在本研究中，我们开发了一种实用策略，用于在具有随机分布微金字塔结构的硅衬底上直接生长保形石墨烯涂层。所制备的无需转移的石墨烯具有高均匀性（单层含量约95%）、低缺陷密度和优异的保形性，即使在高曲率特征（如微金字塔顶点）上也是如此。石墨烯薄膜不仅忠实地复制了底层微观结构，还赋予了有利的表面性质，包括强荧光猝灭、优异的化学稳定性、增强的分子吸附和改善的电荷转移相互作用。所有这些性质对于有效的表面增强拉曼散射（SERS）至关重要。这种石墨烯包覆的金字塔形衬底能够对罗丹明6G（R6G）进行可重复且稳定的SERS检测，具有约10 M的检测限、超过30天的优异长期稳定性以及在毫米尺度上约10%的低空间信号变化。通过用银纳米颗粒进一步修饰石墨烯包覆的金字塔形衬底，R6G的检测限提高到5.5×10 M，具有1.08×10的高分析增强因子。这种增强的性能源于微结构表面的光捕获能力、石墨烯界面引起的化学增强以及等离子体纳米颗粒提供的电磁放大之间的协同相互作用。这些发现为高性能SERS平台的设计提供了有价值的见解。本研究还提出了一种直接合成用于表面功能化的保形石墨烯的实用方法，有望在传感、光电子学和催化等广泛应用中得到应用。
