Polydopamine-mediated in situ growth of multibranched Au mesocrystals on carbon nanotube foams for sensitive, uniform and stable SERS detection

A facile, one-pot synthesis method is proposed for the in situ growth of multibranched gold (Au) mesocrystals on polydopamine (PDA)-modified three-dimensional (3D) carbon nanotube (CNT) foams using cetyltrimethylammonium bromide (CTAB) and silver nitrate (AgNO 3 ) as shape-directing agents. The synthesized Au mesocrystals exhibit complex 3D architectures composed of ultra-long branches (exceeding 1 μm) with sharp tips and serrated edges. Their morphology can be precisely tuned on CNT foams by adjusting the concentrations of CTAB and AgNO 3 in the growth solutions. The resulting CNT foam-multibranched Au mesocrystal hybrids exhibit high surface-enhanced Raman scattering (SERS) sensitivity, enabling the detection of rhodamine 6G and thiram at concentrations as low as 1 × 10 –11  M and 1 × 10 –10  M, respectively. Additionally, the 3D SERS substrates exhibit excellent uniformity, reproducibility, and long-term stability, maintaining high SERS activity after 10 weeks of storage. Importantly, the SERS substrates achieve sensitive detection of thiram on apple peels down to 2.4 ng/cm 2 . This work provides a promising strategy for the efficient fabrication of high-performance 3D SERS platforms for practical sensing applications. Graphical