Filtration‐Assisted Fabrication of Large‐Area Uniform and Long‐Term Stable Graphene Isolated Nano‐Ag Array Membrane as Surface Enhanced Raman Scattering Substrate. Issue 4 (21st December 2017) - Ouyang, Lei
Abstract: In this research, a facile strategy to obtain graphene isolated uniform Ag array membrane that are stable for long‐term use as surface enhanced Raman scattering (SERS) substrates is demonstrated. The fabrication process consisted of three main steps: interfacial assembly of Ag nanoparticles (NPs) into an array, transferring the Ag array to a membrane, and tightly wrapping the Ag array with graphene. The fabricated Ag array and graphene layer structure is tightly packed with effective electromagnetic coupling and electron transferring as confirmed by X‐ray photoelectron spectroscopy, UV‐vis spectra and Raman analysis. Owing to the uniform and effective electromagnetic coupling between Ag NPs and chemical enhancement from tightly wrapped graphene, this hierarchical membrane exhibited excellent SERS enhancing ability (an enhancement factor of 7.3 × 10 8 ) and large area uniformity (with relative standard deviation less than 5.91% for 50 times of detection over an area up to 9 cm 2 ). Due to the protection effect by graphene as both an isolation layer and an electron shuttle, this substrate showed out‐standing long‐term stability (stable more than 25 weeks). Specific functions of graphene in fluorescence quenching and photo‐bleaching inhibition further contributed to intrinsic Raman information access. The obtained flexible membrane based multi‐layer architecture is also easy of use for real application. Abstract : A straight forward strategy is proposed for the fabrication of graphene wrapped Ag array based SERS substrate with good sensitivity, homogeneity and long‐term stability. The flexible membrane contains densely assembled Ag array to produce uniformly distributed hot spots, and tightly wrapped graphene cover could also act as a electron shuttle to protect Ag from reaction and direct interaction with targets.