Using a Graphene-Polyelectrolyte Complex Reducing Agent To Promote Cracking in Single-Crystalline Gold Nanoplates.

It is a challenge to produce single-crystalline gold nanoparticles having regular size definition designed for controlled light absorbance and internal structural inhomogeneities to enhance electro-magnetic fields. Here, we report a synthetic strategy to generate large single-crystalline triangular or hexagonal gold nanoplates with multiple cracks within the plates using a graphene-polyelectrolyte complex as both a surface adsorbent and bulk reducing agent. Large-scale gold nanoplates can be synthesized within 48 h. First-principles calculations indicate that the nanoplates have a kinetically limited morphology resulting from prior growth of {111} facets confined by the graphene-polyelectrolyte multilayer. The nanocracks result from the inability of the bulk reducing agent to enter narrow defect spaces during growth that remained permanently. The nanoplates had extraordinary physical-chemical detection sensitivity when used for surface-enhanced Raman scattering (SERS) and surface-enhanced infrared absorption (SEIRA). The limit of rhodamine 6G (Rh6G) SERS detection is as low as 5 × 10-13 M. The gold nanoplates also showed a remarkable light-to-heat conversion efficiency (68.5%). The approach described may be applicable to other metals so that tunable nanostructures can be generated by the graphene-polyelectrolyte multilayer strategy.