Ascorbic acid-driven formation of defect-rich Cu₂O Nanocubes toward durable and versatile Raman detection

Area of Science:

• Materials Science
• Nanotechnology
• Chemistry

Background:

• Semiconductor-based surface-enhanced Raman scattering (SERS) substrates are difficult to prepare due to challenges in controlling morphology, defect chemistry, and stability.
• Existing methods often struggle to achieve simultaneous control over these critical substrate properties.

Purpose of the Study:

• To develop a facile hydrothermal synthesis method for Cu₂O nanostructures using l-ascorbic acid (AA).
• To investigate the role of AA in controlling the morphology, defect chemistry, and SERS performance of Cu₂O.
• To establish a stable and practical SERS substrate for detecting both cationic and anionic analytes.

Main Methods:

• Hydrothermal synthesis of Cu₂O nanostructures with varying amounts of l-ascorbic acid (AA).
• Characterization of nanostructures using techniques such as EPR spectroscopy and zeta potential analysis.
• Evaluation of SERS performance with both cationic and anionic analytes.

Main Results:

• l-ascorbic acid acted as a shape-directing and mild reducing agent, inducing phase transition to Cu₂O nanocubes and facilitating morphological evolution.
• Optimized Cu₂O_AA30 nanocubes exhibited abundant copper vacancies, confirmed by EPR, leading to defect-mediated charge transfer enhancement.
• The Cu₂O_AA30 substrates demonstrated strong SERS responses for diverse analytes and maintained stability for over two months.

Conclusions:

• The dual role of AA in synthesis enables precise control over Cu₂O nanostructure properties for SERS.
• Defect-mediated charge transfer is the dominant SERS enhancement mechanism, surpassing electrostatic adsorption.
• The developed Cu₂O_AA30 substrates offer a stable, practical, and highly effective solution for SERS applications.