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Bonding geometry engineering of metal–oxygen octahedra is a facile way of tailoring various functional properties of transition metal oxides. Several approaches, including epitaxial strain, thickness, and stoichiometry control, have been proposed to efficiently tune the rotation and tilt of the octahedra, but these approaches are inevitably accompanied by unnecessary structural modifications such as changes in thin‐film lattice parameters. In this study, a method to selectively engineer the octahedral bonding geometries is proposed, while maintaining other parameters that might implicitly influence the functional properties. A concept of octahedral tilt propagation engineering is developed using atomically designed SrRuO 3 /SrTiO 3 (SRO/STO) superlattices. In particular, the propagation of RuO 6 octahedral tilt within the SRO layers having identical thicknesses is systematically controlled by varying the thickness of adjacent STO layers. This leads to a substantial modification in the electromagnetic properties of the SRO layer, significantly enhancing the magnetic moment of Ru. This approach provides a method to selectively manipulate the bonding geometry of strongly correlated oxides, thereby enabling a better understanding and greater controllability of their functional properties.

A clear experimental explanation of the contribution of Mott and Peierls transitions to the insulator−metal transition (IMT) characteristics in vanadium dioxide (VO 2 ) is still lacking. Examining the crystal and electronic structures of epitaxial VO 2 films grown at various deposition temperatures, a Mott or a Peierls transition was observed. The VO 2 film deposited at 500 °C showed suppressed Peierls transition characteristics because of the large inplane compressive strain in the insulating phase. The VO 2 films deposited at 600 and 650 °C had a higher IMT temperature because of the relaxation of both the in-plane and out-of-plane strain, and there were abundant V 4+ states. Therefore, it was related to a collaborative Mott−Peierls transition. Finally, the VO 2 film deposited at 720 °C showed a suppressed Mott transition because of the abundance of V 3+ states in the insulating phase. Furthermore, an analysis of the electronic structure of the insulating and metallic phases using in situ X-ray photoelectron spectroscopy and X-ray absorption spectroscopy provide a complete band diagram to support the above explanation of the deposition-temperature-dependent IMT characteristics.

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Studies on the hydrogen incorporated M1 phase of VO2 film have been widely reported. However, there are few works on an M2 phase of VO2. Recently, the M2 phase in VO2 has received considerable attention due to the possibility of realizing a Mott transition field-effect transistor. By varying the postannealing environment, systematic variations of the M2 phase in (020)-oriented VO2 films grown on Al2O3(0001) were observed. The M2 phase converted to the metallic M1 phase at first and then to the metallic rutile phase after hydrogen annealing (i.e., for H2/N2 mixture and H2 environments). From the diffraction and spectroscopy measurements, the transition is attributed to suppressed electron interactions, not structural modification caused by hydrogen incorporation. Our results suggest the understanding of the phase transition process of the M2 phase by hydrogen incorporation and the possibility of realization of the M2 phased-based Mott transition field-effect transistor.

Morphology control of ZnO structures were fabricated by hydrothermal method with simple adjustments of NaOH concentration and Ag–ZnO composite showed superior photoactivity and recyclability for the degradation of MO and RhB.

The structural aspects of the insulator–metal transition (IMT) characteristics of VO2 are sensitive to the octahedral symmetry variation of VO6. By varying substrate orientation (c‐, a‐, and m‐plane Al2O3), the correlation between IMT temperature and local symmetry is investigated. For a VO2 film deposited on m‐plane Al2O3, which has high symmetry due to fewer domain boundaries induced by m‐plane Al2O3, the IMT temperature is low (326.47 K). In contrast, for a film deposited on c‐plane Al2O3 (having lower symmetry), the IMT temperature is the highest (336.74 K) among the films used in this work. Furthermore, temperature‐dependent Raman spectra reveals that the structural phase transition temperature decreases in the order of the VO2 film deposited on c‐, a‐, and m‐plane Al2O3, suggesting that the symmetrical structure reduces the activation energy for IMT by decreasing thermodynamic energy. These results demonstrate that structural symmetry plays a crucial role in lowering the transition temperature.

The use of metal-organic frameworks (MOFs) to solve problems, like environmental pollution, disease, and toxicity, has received more attention and led to the rapid development of nanotechnology. In this review, we discuss the basis of the metal-organic framework as well as its application by suggesting an alternative of the present problem as catalysts. In the case of filtration, we have developed a method for preparing the membrane by electrospinning while using an eco-friendly polymer. The MOFs were usable in the environmental part of catalytic activity and may provide a great material as a catalyst to other areas in the near future.