Cysteine-Induced Multi-Petal Growth on Gold Nanostructures as SERS Substrates and for Electrochemical CO₂ Reduction and Glucose Oxidation

Highly branched nanoparticles are an attractive design that harnesses the advanced properties of nanomaterials for various applications. However, the diversity of branched morphology complicates detailed identification without generalized synthetic approaches. In this study, we develop a universal method for overgrowing Au multipetals (MPs) on various core materials by manipulating cysteine injection sequences during synthesis. This approach enables uniform MP formation on spheres, rods, and triangular plates, even in a large-scale synthesis. Individual petals comprise single-crystalline planes and curved edges with high-index facets. As surface-enhanced Raman spectroscopy substrates, Au MPs exhibit detection limits that are 2 orders of magnitude lower than those of bare spheres. Additionally, Au MPs significantly enhance catalytic performance in electrochemical CO2 reduction and glucose oxidation. This study provides a straightforward synthesis strategy for a class of branched Au nanoparticles and demonstrates their potential applications for chemical and biosensing, catalysis, and photonic devices.