Band Structure Engineering within Two-Dimensional Borocarbonitride Nanosheets for Surface-Enhanced Raman Scattering

Herein, with two-dimensional (2D) borocarbonitride (BCN) as a metal-and plasmon-free surface-enhanced Raman scattering (SERS) platform, we demonstrate a band structure engineering strategy to facilitate the charge transfer process for an enhanced SERS response. Especially, when the conduction band of the BCN substrate is tuned to align with the LUMO of the target molecule, remarkable SERS performance is achieved, ascribed to the borrowing effect from the vibronic coupling of resonances through the Herzberg-Teller coupling term. Meanwhile, fluorescence quenching is achieved due to the efficient charge transfer between the BCN substrate and target molecule. Consequently, BCN can accurately detect 20 kinds of trace chemical and bioactive analytes. Moreover, BCN exhibits excellent thermal and chemical stability, which can not only withstand high-temperature (300 degrees C) heating in the air but also resist long-term corrosion in harsh acid (pH = 0, HCl) and base (pH = 14, NaOH). This work provides new insight into band structure engineering in promoting the SERS performance of plasmon- and metal-free semiconductor substrates.