A dual-functional plasmonic W18O49/rGO heterostructure for ultrasensitive SERS detection and in situ tracking of photocatalytic reactions

Abstract

Low-cost plasmonic semiconductors are ideal substitutes for precious metals in surface-enhanced Raman scattering (SERS) applications. However, developing plasmonic semiconductors with both high-sensitivity SERS performance and the capability to monitor molecular reactions during photocatalysis remains a significant challenge. Herein, 1D plasmonic W₁₈O₄₉ (WO) nanowires were grown on the surface of 2D reduced graphene oxide (rGO) to construct a 1D/2D heterostructure (WO/rGO). The ultrathin 2D-rGO stabilizes the surface oxygen vacancies within 1D-WO for strong localized surface plasmon resonance (LSPR), while facilitating the generation of more hot electrons and effectively mitigating their ultrafast relaxation. The optimized WO/rGO heterostructure demonstrates exceptional SERS performance for target methylene blue (MB) molecules, with the detection limit reaching down to 10⁻¹⁰ M. More intriguingly, the plasmonic WO/rGO heterostructure simultaneously enables boosted photocatalytic MB degradation and in situ SERS monitoring of the catalytic process. Mechanistic studies reveal that the C–H bonds in MB are preferentially cleaved over the aromatic C–C bonds during photocatalysis, providing molecular-level insights into the degradation pathway. This dual-functional plasmonic heterostructure holds great promise for quantitative SERS analysis of bio-chemicals and self-tracking of catalytic reactions.