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Today, Fs defects in MgO as isolated surface neutral oxygen vacancies are in the focus of surface science, catalysis research, and emission coating of microchannel plates. With the 10–4 atom % content at 750 K and under p O2 = 10–9 Torr, estimated by us from the known equilibrium T–x and p–T–x diagrams of MgO, Fs defects remain invisible or difficult-to-detect objects. The MgO(100) → MgO(100) + Fs + 1/2O2 phase transition was studied in MgO films deposited by the metal–organic chemical vapor deposition (MOCVD) procedure from the mixed-ligand Mg precursor on Si substrates at 725 K in the O2 flow where the nonstoichiometric phase (MgO/Fs) is formed in the gas medium containing simultaneous H2, CO, H2O, CO, and O2 species in unbalanced concentrations. Realization of the above transition was proven theoretically and experimentally through kinetic–thermodynamic analysis of the nonequilibrium system with revealing thermodynamic motive forces, i.e., the positive enthalpy and entropy, as well as through a new combination of diagnostic methods including the original differential dissolution method, due to which separate determination of the point and morphological defects was achieved. It was found that Fs defects occur when oxygen in the immediate vicinity to the substrate surface is replaced practically completely by the oxidized products of the precursor and the resulting oxygen pressure becomes enough for this process. The 90 mass % of the as-deposited MgO-film-involved (MgO/Fs) phase; its chemical activity is demonstrated through dissolution in hot water, while the electron donor activity is through 9 at 750 eV secondary electron yield. A good understanding of gas-phase reactions between the precursors and oxygen provides the fundamental basis of the MOCVD process to deposit MgO films that are dense, free from carbon, and of homogeneous texture. This makes the MOCVD process suitable also for use as coatings of microchannel plates.

The development of solvent-free methods for the synthesis of catalysts is one of the main tasks of green chemistry. A nickel–alumina catalyst for CO2 methanation was synthesized by solid-state combustion method using hexakis-(imidazole) nickel (II) nitrate complex. Using X-ray Powder Diffraction (XRD), Transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and Hydrogen temperature-programmed reduction (H2-TPR), it was shown that the synthesized catalyst is characterized by the localization of easily reduced nickel oxide on alumina surface. This provided low-temperature activation of the catalyst in the reaction mixture containing 4 vol% CO2. In addition, the synthesized catalyst had higher activity in low-temperature CO2 methanation compared to industrial NIAP-07-01 catalyst, which contained almost three times more hard-to-reduce nickel–aluminum spinel. Thus, the proposed approaches to the synthesis and activation of the catalyst make it possible to simplify the catalyst preparation procedure and to abandon the use of solvents, which must be disposed of later on.