Oxygen-driven ReS2–ReO3 hybrid interfaces facilitate dual charge transfer pathways for noble-metal-free SERS

Abstract

Metallic 1T′-phase transition metal dichalcogenides (TMDs) are promising noble-metal-free surface-enhanced Raman spectroscopy (SERS) substrates due to their high carrier density and abundant surface states. However, their performance remains limited by weak surface interactions and inefficient interfacial charge transfer. Here, we develop an oxygen-driven phase engineering strategy to construct ReS₂–ReO₃ hybrid interfaces via controllable thermal annealing of 1T′-ReS₂. Theoretical simulations reveal that oxygen incorporation and the formation of localized ReO₃ domains induce surface charge redistribution and enrich active binding sites. Through EC-SERS, femtosecond transient absorption (fs-TA) and spectroscopic experiments, it is further confirmed these hybrid interfaces facilitate charge transfer, both across the ReS₂–ReO₃ domains and at the molecule–substrate interface, which leads to stronger adsorption and improved Raman signal enhancement. The optimized substrate exhibits a 38.9-fold enhancement factor (EF) improvement for rhodamine 6G (R6G) detection compared to pristine ReS₂, achieving a detection limit of 10⁻⁷ M while demonstrating excellent uniformity and stability performance. This work presents a generalizable route to noble-metal-free SERS through interface and electronic structure engineering in TMDs systems.