We registered surface enhanced Raman scattering (SERS) spectra of the human lactoferrin molecules adsorbed on a silvered porous silicon (por-Si) from 10⁻⁶–10⁻¹⁸ M solutions. It was found that the por-Si template causes a negative surface potential of silver particles and their chemical resistivity to oxidation. These properties provided to attract positively charged lactoferrin molecules and prevent their interaction with metallic particles upon 473 nm laser excitation. The SERS spectra of lactoferrin adsorbed from 10⁻⁶ M solution were rather weak but a decrease of the concentration to 10⁻¹⁰ M led to an enormous growth of the SERS signal. This effect took place as oligomers of lactoferrin were broken down to monomeric units while its concentration was reduced. Oligomers are too large for a uniform overlap with electromagnetic field from silver particles. They cannot provide an intensive SERS signal from the top part of the molecules in contrast to monomers that can be completely covered by the electromagnetic field. The SERS spectra of lactoferrin at the 10⁻¹⁴ and 10⁻¹⁶ M concentrations were less intensive and started to change due to increasing contribution from the laser burned molecules. To prevent overheating the analyte molecules on the silvered por-Si were protected with graphene, which allowed the detection of lactoferrin adsorbed from the 10⁻¹⁸ M solution.

This study reveals a significant improvement in surface-enhanced Raman scattering (SERS) activity of Ag/ZrO₂ substrates covered with a few-layer graphene preliminary exposed to ultraviolet (UV) light. The SERS-active substrates are formed by the “silver mirror” deposition of Ag nanoparticles on annealed zirconia blocks. The film composed of ~3 graphene layers is grown on copper foil by a chemical vapor deposition and then wet-transferred to the SERS-active substrates. The graphene-free Ag/ZrO₂ samples are found to provide an enhancement of the Raman scattering from rhodamine 6G (R6G) at a micromolar concentration, which is associated with combined effects from the surface plasmon resonance in the Ag nanoparticles and a charge transfer facilitated by zirconium dioxide. It is revealed that the SERS signal from the analyte molecules can be suppressed by a UV exposure of the Ag/ZrO₂ samples due to photocatalytic activity of the wide band gap semiconductor. However, if the samples are covered with a few-layer graphene (Gr/Ag/ZrO₂) it prevents the dye molecule decomposition upon the UV treatment and improves SERS activity of the substrates. The 365 nm treatment leads to a 40% increase in the 10^–6 M R6G SERS spectrum intensity, while the 254 nm irradiation causes it to rise by 47%, which is explained by different responses from the surface and bulk zirconia crystals to the short and long UV wavelengths. This enhancement is attributed to the distinct responses of surface and in-depth zirconia crystals to varied UV wavelengths and underscores the pivotal role of graphene as a protective and enhancing layer.

This study investigates the effect of temperature on the performance of the single-walled carbon nanotube (SWCNT) film/Si photodetector. Specifically, the photocurrent across a SWCNT/Si heterojunction when illuminated with light of 632.8 nm wavelength of different powers was studied in detail in a wide temperature range, from 20 to 300 K. The objective was to determine the parameters of the heterojunction, which is inherently inhomogeneous, and to identify the main ones that determine the optoelectronic figures of merit of a photodetector based on it. The barrier height and its temperature dependence were determined within the framework of the theory of thermionic emission, taking into account the non-uniform distribution of the barrier height over the heterojunction area. The parameters of the heterojunction and SWCNT/Si interface and their temperature dependences were calculated based on the known temperature dependences of the concentration of charge carriers and ionized impurities in Si using the Poisson equation based on Fermi–Dirac statistics. The obtained results indicate the importance of interplay between the effects of reducing the barrier height and the processes of decreasing the separation efficiency of nonequilibrium charge carriers and increasing the rate of their recombination.

Graphene-based hybrid magnetic systems are promising platforms for spintronic applications, yet the mechanisms governing magnetic correlations in these two-dimensional (2D) architectures remain incompletely understood. Here, we investigate the magnetic behavior of Co/CoO core–shell nanoparticles electrochemically deposited on graphene, focusing on the 25–50 K range, where the coercivity and exchange bias field reach their maximum values. Using a modified 2D integral-law framework for approaching magnetic saturation, adapted for 2D systems via the Meyer integral transform, we reconstruct the real-space correlation functions (CFs) of the magnetic anisotropy axes and extract the main micromagnetic parameters. The analysis reveals three distinct types of CFs, monotonic, non-monotonic, and jump-like, which we tentatively associate with different microstructural configurations, including isolated nanoparticles, dense clusters, and sparse conglomerates separated by graphene domain boundaries. The monotonic CFs exhibit long-range coherence of the magnetic anisotropy axes extending over nearly one micrometer. We propose that this long-range behavior may arise from a dual-scale mechanism: indirect RKKY-type exchange through the graphene layer, combined with strong local anisotropy from the CoO shells, which pins the magnetization of individual Co cores via exchange bias. These interpretations are presented as plausible hypotheses, and further experimental verification is required.