Hydrophilic layers of porous silicon are prepared by single- or two-step anodization and characterized by evaluating their surface hydrophilicity and contents of functional groups using IR spectroscopy and adsorption of acid-base indicators with differentpKavalues. The surface functional composition of the synthesized samples is shown to be adjustable depending on the anodization current density. The surface of samples obtained at anodization current density 30 mA/cm²is predominantly occupied withpKa2.5 corresponding to ≡Si–OH groups. The increase of current density to 80 mA/cm²results in the increase of surface functional nonuniformity with the formation of versatile centers, primarily Lewis acidic sites corresponding to Si atoms, as indicated by selective indicator adsorption in agreement with the disappearance of Si–H bonds in IR spectra and overall surface disordering according to SEM and AFM data.

The differences in the electronic structure and composition of porous silicon samples obtained under identical conditions of electrochemical etching on the most commonly used n- and p-type substrates...

Approaches are being developed to create composite materials with a fractal-percolation structure based on intercalated porous matrices to increase the sensitivity of adsorption gas sensors. Porous silicon, nickel-containing porous silicon, and zinc oxide have been synthesized as materials for such structures. Using the impedance spectroscopy method, it has been shown that the obtained materials demonstrate high sensitivity to organic solvent vapors and can be used in gas sensors. A model is proposed that explains the high sensitivity and inductive nature of the impedance at low frequencies, considering the structural features and fractal-percolation properties of the obtained oxide materials.