Programmable Interfacial Energy Alignment in Plasmonic Metal-Organic Frameworks for Selective Molecular Probing on Complex Heterogeneous Surfaces

Abstract

In situ identification and spatially resolved analysis of multicomponent species on complex heterogeneous surfaces remain formidable challenges in surface science, advanced manufacturing, and cultural heritage conservation. Although surface-enhanced Raman scattering (SERS) provides highly sensitive molecular fingerprints, existing platforms often struggle to simultaneously achieve robust interfacial contact and discriminable responses on rough, porous, and compositionally heterogeneous solids. Here, we report a programmable interfacial energy-alignment strategy by integrating a core–shell plasmonic metal-organic framework (MOF) heterojunction, Fe₃O₄@SiO₂@UiO-66(X)@Ag triangular nanoplates (Ag TNs), into an injectable poly(vinyl alcohol) (PVA) microgel matrix to construct a self-adaptive SERS chip. The microgel fills surface asperities and establishes semipermeable conformal contact. Upon dehydration, it locally densifies interfacial nanogaps and reconstructs hotspot networks, thereby promoting more effective interfacial coupling within accessible pores and cracks while improving signal stability and reproducibility. Meanwhile, ligand engineering of UiO-66(X) modulates the interfacial electronic structure and favors phase-dependent charge-transfer-assisted enhancement, whereas tuning the tip sharpness of Ag TNs regulates localized surface plasmon resonance (LSPR) coupling under different excitation wavelengths. Excitation- and ligand-controlled SERS experiments, together with density functional theory calculations, provide an electronic-structure rationale for the observed preferential responses and support the involvement of cooperative electromagnetic and charge-transfer-assisted enhancement contributions. As a result, the chip enables phase-resolved identification and spatial mapping of corrosion products in model multilayer systems, as well as low-disturbance in situ analysis and interval-based corrosion-state estimation of excavated bronze artifacts. This work provides a general materials-design framework for programmable interfacial energy-level regulation toward molecular sensing and chemical imaging on complex solid surfaces.