Visible light‐enhanced and degradable SERS substrates based on g‐C3N4/Au NP hybrid structures

Abstract In this study, a visible light‐activated and degradable surface‐enhanced Raman spectroscopy (SERS) substrate was fabricated based on graphite carbon nitride (g‐C 3 N 4 ) and gold nanoparticle (Au NP) hybrid structures. By using porous structure of g‐C 3 N 4 as the support, Au NP arrays can be formed through sputtering of a thin Au film. Typical surface Raman enhancement effect can be observed by using p ‐toluenethiol as the probe molecule. Interestingly, it was found that the Raman signal of probe molecules could be enhanced 2.7 times by pre‐illumination of visible light for a short time within 2 min, while the Raman signal decreased significantly about five times with further long‐term irradiation of more than 60 min. The electromagnetic enhancement effect of Au NP array on semiconductor materials with various extinction coefficients was studied by FDTD simulations. Furthermore, a charge transfer enhancement mechanism was proposed based on band structure of g‐C 3 N 4 /Au NP hybrid substrate and molecular orbitals. Our experimental and simulation results demonstrated an approach to construct a visible light‐activated SERS substrate with enhancement and degradation properties based on porous organic semiconductors.