Au Atoms Anchored on Amorphous C.

Area of Science:

• Materials Science
• Nanotechnology
• Spectroscopy

Background:

• Surface-enhanced Raman scattering (SERS) typically relies on noble metal nanoclusters.
• Downsizing nanoclusters to the atomic level eliminates the surface plasmon resonance effect, limiting SERS research at the atomic scale.
• Existing SERS substrates often suffer from poor stability and reproducibility due to nanoparticle aggregation.

Purpose of the Study:

• To investigate the potential of single-atom noble metals for enhanced Raman scattering.
• To develop a novel SERS substrate with enhanced stability and reproducibility.
• To elucidate the mechanism behind single-atom enhanced Raman scattering.

Main Methods:

• Anchoring single gold atoms onto amorphous carbon nitride (C3N4) nanosheets (Au1/ACNs).
• Characterizing the synthesized Au1/ACNs for uniform atomic dispersion.
• Evaluating the spectral stability, reproducibility, and enhancement factor of the Au1/ACNs as SERS substrates.
• Investigating the underlying enhancement mechanism through theoretical analysis of charge transfer and electronic properties.

Main Results:

• A novel single-atom enhanced Raman scattering (SAERS) effect was discovered using Au single atoms on amorphous C3N4 nanosheets (Au1/ACNs).
• The Au1/ACNs exhibited excellent spectral stability and reproducibility due to uniform atomic dispersion, preventing hotspot aggregation.
• An impressive enhancement factor of 2.5 × 10^4 was achieved with only ~2.5% Au-coated area.
• A synergistic effect between Au single atoms and C3N4 was identified, increasing molecular dipole moment and polarizability.
• A new single-atom charge transfer mechanism was proposed, highlighting superior electron delocalizability and electronic density of states in single Au atoms compared to clusters.

Conclusions:

• Single-atom enhanced Raman scattering (SAERS) is a viable phenomenon, distinct from traditional SERS.
• Uniformly dispersed single atoms on suitable supports offer superior stability and reproducibility for Raman spectroscopy.
• The findings establish a new paradigm for applying single-atom materials in enhanced Raman spectroscopy and related fields.