Rational Design of Hyperbranched Au Nanowires on Carbon Nanotube Foams for in Situ SERS Monitoring of Catalytic Reactions

Integrating strong plasmonic enhancement with high catalytic activity in a single Au nanostructure remains a challenge for in situ SERS monitoring. Herein, we report a facile one-pot synthesis strategy for hyperbranched Au nanowires (HB-AuNWs) directly grown on carbon nanotube (CNT) foams, establishing a dual-functional platform that integrates SERS sensing and plasmonic catalysis. Fine-tuning reaction parameters enables effective control over the branch density of HB-AuNWs, and samples with denser branches exhibit enhanced SERS intensities. This unique architecture combines a one-dimensional conductive backbone with densely distributed branches, facilitating efficient hot-electron transport, strong electromagnetic field enhancement, and abundant active sites. As a result, the HB-AuNWs achieve sensitive SERS detection of 4-aminothiophenol (4-ATP) down to 10 –11 M with excellent uniformity, reproducibility, and long-term stability, while simultaneously driving the plasmon-driven dimerization of 4-ATP/4-nitrothiophenol (4-NTP) into 4,4′-dimercaptoazobenzene (DMAB). Furthermore, the platform enables in situ SERS monitoring of the six-electron reduction of 4-NTP to 4-ATP with a rate constant of 0.018 s –1 measured under 1.0 M HCl conditions, demonstrating its capability for quantitative monitoring of plasmon-driven multielectron reactions. This work establishes a versatile analytical platform that combines plasmonic catalysis with sensitive SERS sensing, providing a promising route for catalytic studies and real-time reaction monitoring.