Dual-Functional Plasmonic W18O49/rGO Heterostructure for Ultrasensitive SERS Detection and In Situ Tracking of Photocatalytic Reaction

Abstract

Low-cost plasmonic semiconductors are ideal substitutes of 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 nanowires (WO) were grown on the surface of 2D reduced graphene oxides (rGO) to construct a 1D/2D heterostructure (WO/rGO). The ultrathin 2D-rGO stabilize the surface oxygen vacancies within 1D-WO for strong localized surface plasmon resonance (LSPR), while facilitating more hot electron generation and effectively mitigating their ultrafast relaxation. The optimized WO/rGO heterostructure demonstrates exceptional SERS performance for target methylene blue (MB) molecules with 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-track catalytic reaction.