The formation of nano-pores in graphene crystal structure is alternative way to engineer its electronic properties, chemical reactivity, and surface interactions, enabling applications in technological fields such as sensing, energy and separation. The past few years, nano-perforation of graphene sheets has been accomplished by a variety of different methods suffering mainly from poor scalability and cost efficiency issues. In this work, we introduce an experimental protocol to engineer nanometer scale pores in CVD graphene membranes under ambient conditions, using low power ultra-short laser pulses and overcoming the drawbacks of other perforation techniques. Using AFM and SEM we visualized and quantified the nanopore network while Raman spectroscopy is utilized to correlate the nano-perforated area with the nanotopographic imaging. We suggest that Raman imaging provides the identification of nanoporous area and, in combination with AFM, we provide solid evidence for the reproducibility of the method, since under these experimental conditions, nanopores of a certain size distribution are formed.

A TiO2 thin film, prepared on fluorine-doped indium tin oxide (FTO)-coated glass substrate, from commercial off-the-shelf terpinol-based paste, was used to directly adsorb Ag plasmonic nanoparticles capped with polyvinylpyrollidone (PVP) coating. The TiO2 film was sintered before the surface entrapment of Ag nanoparticles. The composite was evaluated in terms of spectroelectrochemical measurements, cyclic voltammetry as well as structural methods such as scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray diffraction (XRD). It was found that the Ag nanoparticles are effectively adsorbed on the TiO2 film, while application of controlled voltages leads to a fully reversible shift of the plasmon peak from 413 nm at oxidation inducing voltages to 440 nm at reducing voltages. This phenomenon allows for the fabrication of a simple photonic switch at either or both wavelengths. The phenomenon of the plasmon shift is due to a combination of plasmon shift related to the form and dielectric environment of the nanoparticles.

Phonon lifetimes are fundamental physical parameters playing a significant role in phonon transport and thermal conductivity of two-dimensional materials. We employed the time-resolved incoherent anti-Stokes Raman scattering (TRIARS) technique to capture the G phonon dynamics and to extract the G phonon lifetimes in supported exfoliated and polycrystalline chemical vapor deposited (CVD) graphene samples of various thickness. We have found that substrate reduces considerably the G phonon lifetime of exfoliated monolayer graphene while the corresponding lifetimes for bilayer and trilayer converge gradually close to that of graphite. The lifetimes of CVD monolayers are systematically lower than exfoliated ones mainly due to the presence of various types of structural defects. Besides, the electron–phonon coupling strength of graphite is determined to be 10.6 cm–1, in excellent agreement with theoretical predictions for graphene, justifying that the lifetimes of suspended graphene and graphite are similar.