Beyond Plasmonics: Atomic-Scale SERS Platforms for Plasmon-Free Photocatalysis Monitoring via Charge Transfer Mechanisms

Surface-enhanced Raman scattering (SERS) leveraging single-atom or small-cluster systems represents an emerging frontier in molecular sensing and catalytic monitoring. Unlike conventional plasmonic SERS substrates, these systems rely on charge transfer mechanisms rather than electromagnetic enhancement, enabling possible SERS monitoring of their own photocatalytic reaction process without plasmon-induced side reactions. This Perspective explores the working principles of charge transfer mechanisms in single-atom/small-cluster systems supported by semiconducting and metallic substrates, highlighting their distinct electronic interactions and energy-level matching strategies. This integration of SERS with photocatalytic processes offers unprecedented opportunities for real-time plasmon-free reaction monitoring. Challenges in anchoring single atoms or small clusters onto suitable support materials, methods for simultaneously optimizing SERS performance and photocatalytic activity, and approaches for promoting SERS uniformity are critically discussed.